GISF Research Paper 006
Scientific Basis for
Forest Management in
the U.S. Inland West
A Review and Synthesis
Program on Forest Health
Yale University
School of Forestry & Environmental Studies
Global Institute of Sustainable Forestry
Scientific Basis for Forest
Management in the U.S.
Inland West
A Literature Review
Ann E. Camp, Mary L. Tyrrell, Linda Kramme, Jennifer Karanian, and
Christopher Thompson
December 2006
GISF Research Paper 006
Yale Program on Forest Health
Yale University
School of Forestry and Environmental Studies
Global Institute of Sustainable Forestry
360 Prospect Street, New Haven, Connecticut 06511 USA
www.yale.edu/gisf
This project was supported by a grant from Boise Cascade
2
Yale University’s Global Institute of Sustainable Forestry
3
Table of Contents
Introduction ..................................................................................................................................................4
Old Growth Characterization .........................................................................................................................5
Post-fire Salvage Logging .............................................................................................................................15
Insects and their Management ...................................................................................................................27
Annotated Bibliographies
Old Growth Characterization ...........................................................................................................48
Post-fire Salvage Logging ................................................................................................................61
Insects and their Management ........................................................................................................73
Tables
Old Growth Characterization .........................................................................................................106
Post-fire Salvage Logging ..............................................................................................................110
Insects and their Management .....................................................................................................114
4
Scientific Basis for Forest Management in the U.S. Inland West
Introduction
The purpose of this report is to compile, analyze, and
make available in one document the latest science
related to old growth forest dynamics, and forest
management toward maintaining forest health in the
inland northwest of the United States. In this instance,
‘management toward maintaining forest health’ is
defined as silvicultural treatments that reduce the
likelihood or impacts from wildfire and insect outbreaks.
Current definitions of old growth forests are frequently
driven as much by societal values and beliefs as they
are by science. Definitions of old growth should vary
depending on the ecosystem in question, but often,
rigid definitions are widely promulgated, without regard
to a particular forest’s history and characteristics. In
fire-regulated ecosystems, these definitional problems
are often exacerbated by a history of fire exclusion.
Forests having some old growth characteristics are not
sustainable given an inherent disturbance regime that
includes fires and periodic insect outbreaks.
It is expected that this research will assist inland west
forest managers by: 1) developing a scientifically
credible working definition of old growth; 2)
synthesizing the current understanding of managing
for forest heath, particularly as it relates to thinning
operations in forests heavily impacted by defoliating
insects and bark beetles; and 3) developing guidelines
for management activities in forests following wildfires.
We conducted an extensive search of the recent (post1990) literature on the following topics: definition of
old growth; the impacts of thinning in insect killed
forests; and salvage logging following fire. We reviewed
literature from peer-reviewed journals and other
credible sources (such as Forest Service and other
agency technical publications). After compiling
relevant literature, we reviewed and synthesized it
toward providing a better understanding of the current
science related to these topics. In addition, the
investigators have provided commentary based on
their expertise, experience, and understanding of the
issues of forest management in the inland west.
Geographical interpretations of the “inland northwest”
vary; in this paper we restrict our definition to nonalpine forests in interior British Columbia, eastern
Washington and Oregon, and parts of Idaho, Montana,
and Wyoming – generally forests between the
Cascades and Rocky Mountains. We also include a
few studies from adjacent areas that were especially
relevant to one or more of the above-listed topics.
Yale University’s Global Institute of Sustainable Forestry
5
Old Growth Characterization in Inland Northwest Forests
A Review and Synthesis
Ann E. Camp, Mary L. Tyrrell and Christopher Thompson
This paper is a review of current literature on the
scientific basis for characterizing old-growth forests in
the inland Pacific Northwestern United States (east of
the crest of the Cascades Mountains) and interior
southern British Columbia, Canada. The question
‘What is old-growth?’ seems deceptively simple. But
not only is the scientific community in disagreement
over the definition of old growth forests, the term itself
has been interpreted differently by many people (for a
review of the many hundred published terms, see
Lund 2005). One thing about which there is general
agreement is that more research is needed to
accurately characterize the old forests of the inland
West (WSDNR 2005; Youngblood et al. 2004; Spies et
al. 2006; and others).
The inland Pacific Northwest has a predominately dry
continental climate. At the landscape level, a
heterogeneous mix of dry to mesic conditions is
strongly influenced by topography, physiography, and
elevation (Camp et al. 1997; Agee 2003; Spies et al.
2006; and others). Climate (precipitation and
temperature) topography (aspect, slope and landform)
and disturbance regimes (especially fire) are the
primary drivers of forest composition (Franklin and
Dyrness 1988, Agee 2003). Most forests are
dominated by ponderosa pine (Pinus ponderosa)
and/or Douglas-fir (Pseudotsuga menziesii); other
co-dominants vary with site conditions and past
disturbance history, and include grand fir (Abies
grandis), lodgepole pine (Pinus contorta), and western
larch (Larix occidentalis). Based on existing information
about the structure, disturbance dynamics and
ecological process in these forests, Spies et al. (2006)
group them into three major types: (1) ponderosa pine,
(2) mixed-conifer/evergreen on dry sites and (3)
mixed-conifer/evergreen on mesic sites. These
categories generally reflect what is reported in the
literature; the majority of the research on old growth
and forest development comes from studies of forests
from the first two categories.
Most definitions of old growth rely on one or both of
two attributes that are relatively easy to measure: tree
age and stand structure. This raises numerous
questions. What constitutes old? Is it the age of
individual trees and if so, where is the line drawn? Is
tree size a factor? Can size be a surrogate for age? In
general, as forests age, they tend to become
structurally more complex and exhibit greater
structural heterogeneity. But, as Wells et al. (1998)
point out, developing a definitions of old growth is
difficult; the point at which a forest attains old growth
status is as much a matter of judgment as science.
Concepts and characterizations of old-growth forests
are much more developed for the western and coastal
regions of the Pacific Northwest. The structural and
functional attributes of old growth forests west of the
Cascade crest have been extensively studied for
several decades (Franklin et al, 2002; and many
others). While it may be tempting to extrapolate the
results of this research to all forests in the Pacific
Northwest, the marked differences in climate, land use
history, and disturbance regimes east of the Cascades
crest makes doing so problematic (WSDNR 2005). In
6
Scientific Basis for Forest Management in the U.S. Inland West
contrast to the extensive research on old growth west
of the Cascades, there are few studies documenting
old growth characteristics from inland Pacific
Northwestern forests. We found only four field–based
studies conducted during the past 10 years and
published in the peer-reviewed literature: (Antos and
Parish 2002, Camp et al. 1997, Wright and Agee
2004, and Youngblood et al. 2004). These studies
were conducted in different forest types, making it
difficult to extract a generalized definition of old growth
from this small body of research. In addition to these
published studies, several field-based administrative
studies and theses exist: Ohlson 1996; DeLong, 1997;
Schellhaas et al., 2000, 2003; Gray et al. undated ~
2000). This body of research does not address old
growth forests per se, but does document changes to
inland Pacific Northwestern forests following the
exclusion of fire as a dominant disturbance.
The pre-European settlement ‘old growth’ forests that
developed east of the Cascades were of two very
different types, each of which developed under
different disturbance regimes (Camp et al. 1997). In
the drier forest types, frequent low severity fires ignited
by lightning or aboriginals created open park-like
forests dominated by ponderosa pine which is often
considered an early seral (or early successional)
species. Individual pines under this disturbance
regime could survive for many centuries. On more
mesic sites and at higher elevations, less frequent—
but often more severe—fires allowed forests to
temporarily develop the structures and species
compositions more like those of the wetter, west slopes
of the Cascades mountains. Nevertheless, these late
successional forests would be regenerated by fire
much more frequently than their westside
counterparts (Camp et al. 1997).
Adding to the difficulty of defining old growth in the
inland Pacific Northwest is the past century of fire
exclusion, with and without selective or high-grade
timber harvesting; such management practices have
together and separately altered the structure and
composition of these forests. In some cases, fire
exclusion and selective harvesting have created
complex forest structures in relatively young stands;
these stands are frequently identified as old growth.
In this paper we summarize the existing scientific
research on old growth and late-successional forests of
the inland West within four categories often used in
characterizing old growth forests elsewhere: size and
age; structure and disturbance; habitat; and scale. We
also examine the theme of “historical/natural range of
variability” (HRV / NRV) as it applies to old growth in
this region.
Size & Age
The most frequently used criteria for defining old
growth are tree age and size, with many definitions
using a combination of both metrics (Spies et al. 2006;
Franklin & Van Pelt 2004; Arsenault 2003; MacKinnon
& Vold 1998; USFS 1993 and others). A few
definitions rely on only one criterion. Definitions
developed and used by different scientists and
agencies differ markedly (Table 1) and often reflect or
support management objectives. Use of age and/or
size for defining old growth has the dual advantages
of being easily implemented and not overly subjective.
Problems are incurred because past heavy selective
harvesting in inland Pacific Northwestern forests left
few reference stands on which to scientifically base
age and size thresholds. Past harvesting also targeted
trees in the largest size classes, especially ponderosa
pine, western larch, and Douglas-fir. Because of this,
existing stands otherwise old enough to qualify as old
growth may lack a sufficient quantity of trees in larger
size classes (Hessburg et al. 1999, 2000).
Definitions relying on only one criterion can also be
problematic. The Eastside Forests Scientific Society
Panel (convened in 1992 at the request of Congress to
identify and recommend management strategies for
old growth forests east of the Cascades crest in
Washington and Oregon) identified existing old growth
primarily from maps produced by the Audubon
Society’s Adopt-A-Forest Project (Perry et al. 1995).
These maps were based on US Forest Service (USFS)
timber type maps that identified stands where the
average tree diameter exceeded 21”. Locations of
existing old growth were subsequently refined using
aerial photographs and field verification to assure
compliance with USFS regional old growth definitions
(themselves based primarily on age and tree size). The
Yale University’s Global Institute of Sustainable Forestry
actual extent of field verification varied depending on
national forest; thus in many instances there was little
information about the age structure of stands identified
as old growth.
For most old growth classification strategies, the
ecological basis for establishing size and age
thresholds is weak (Spies et al. 2006). The Washington
State Department of Natural Resources (WSDNR)
determined that the USFS Region 6 old-growth
definitions based on age and size class were
inadequate for identifying actual old-growth conditions
on the ground (WSDNR, 2005). A study by
Youngblood et al. (2004) supported the conventional
wisdom that old ponderosa pine forests are multi-aged,
with the oldest cohorts 200 years or older.
In some old growth classifications, large trees are used
as a surrogate for old trees; however, Antos and Parrish
(2002) found the relationship between size and age
was weak for old subalpine fir/lodgepole pine/
Englemann spruce stands in southern British
Columbia. Using size as a surrogate for age potentially
misidentifies old growth in two ways. Trees on
productive sites can attain large diameters at relatively
young ages. Camp et al. (1997) found that stands
containing large trees were not necessarily old growth,
or even old. Especially on productive sites, stands with
trees exceeding 21” dbh were often even aged and <
100 years old. On the other hand, on less productive
sites great age can be attained at relatively small
diameters. Camp (unpublished data) identified
numerous multi-cohort stands in the eastern
Washington Cascades — generally at higher elevations
— composed of trees > 300 years but < 12” dbh.
Structure & Disturbance
In the scientific literature on fire-regulated forests in
the inland Northwest, two different fire regimes are
frequently compared and contrasted. One regime is
characterized as having frequent, low severity fires
while the other is described as having infrequent, but
severe fires (Agee 2003 and others). It is important to
keep in mind that a fire regime describes the kind of
fires that are typical for a particular forest type. Any
given individual fire (a fire event) can deviate from that
average. Therefore, while a forest may have a fire
7
regime characterized by frequent, low severity fires,
that forest might over its long lifespan be visited by
severe fires or fires having a moderate severity. Fire
severity is a measure of the ecological consequences;
Agee (1993) differentiates low, moderate, and severe
fires by the amount of overstory destroyed (10%, 1169%, 70% respectively).
Fire severity could also be categorized by damage to
other vegetation or soils, but overstory mortality is
easier to measure. Fire severity should not be
confused with fire intensity which is a measure of the
amount of energy released along a unit length of
fireline. Two fires with similar intensities could have
vastly different severities, depending on the rate of
speed through the forest and also on the vulnerability
of the trees, for instance whether or not they had thick
or thin bark. A third fire regime, perhaps one much
more prevalent than suggested by the scientific
literature, is the mixed severity regime described by
Agee (1993). These forests experience fires less
frequently than the low severity regime forests. With
more time between successive fires, forests having a
greater amount of complexity develop. Successive fires
are usually not stand replacing, allowing some of that
complexity to persist.
It is particularly difficult to assess fire severity when
reconstructing fire histories. It is often only possible
when documenting fire over larger landscapes where
comparisons among multiple stands can be made.
Ohlson (1996) found that under a disturbance regime
characterized by frequent fire, fire severity shaped
stand structure and composition. Her research
indicated that both were simplified with higher severity
fires and that higher severity fires were associated with
more productive sites. She concluded that as fire
severity decreased, smaller individuals of ponderosa
pine were able to attain overstory canopy positions and
therefore reduce or eliminate the vertical gap between
the understory and overstory trees. These lower
productivity sites that supported less severe fires also
allowed the somewhat less fire tolerant Douglas-fir to
persist.
DeLong (1997) concluded that remnant stands within
a larger matrix forest that had been regenerated by a
single stand replacing fire shared some ecological
characteristics with much older stands; these
8
Scientific Basis for Forest Management in the U.S. Inland West
characteristics were related to the variable influence
of the fire and other disturbances (insects, diseases,
and wind) on stand structure and composition.
DeLong concluded that although fire intensity in
remnants was not sufficient to completely regenerate
them, the fire released some growing space that
resulted in the development of a more complex
understory.
from extinguishing them. Where historical fires burned
under a variety of weather conditions and therefore
resulted in varying degrees of severity, more recent
fires are resulting in a greater proportion of overstory
mortality. The reports by Schellhaas et al. (2000,
2003) document the patchiness of forests under a
mixed-severity fire regime and the current absence of
large trees as a result of past harvesting.
Keeping the preceding information on fire regimes in
mind, stand structure can sometimes allude to the
successional stage of a forest (Antos and Parrish 2002;
Arsenault 2003; Wells et al. 1998; Youngblood 2001;
Youngblood 2004; Spies et al. 2006; Spies 2004; Agee
2003; Franklin et al. 2002). Some recent studies have
shown that older forests in the inland Northwest have
a rich and diverse assembly of dead trees and downed
wood, horizontal and vertical complexity, and
patchiness of canopy and subcanopy dominants, with
several cohorts in close proximity (Youngblood et al.
2004; Antos and Parrish 2002).
Historical disturbance regimes and fire severity in
inland Northwestern forests varied with topography,
climate, geomorphology, soils and vegetation (Spies et
al., 2006; Spies 2004; Camp et al., 1997). The
resulting vegetation pattern was a complex mosaic of
forest types and conditions. Historically, many forests
primarily experienced frequent, low intensity fires,
resulting in old-growth conditions dominated by fire
tolerant (usually early seral) species that were spatially
patchy, but had limited horizontal and vertical
complexity. The majority of the current literature
references forests that developed under this kind of
fire regime, probably because the abundance of fire
scarred old trees and stumps make reconstructing fire
histories relatively simple.
Extremely important to any attempt at characterizing
old forests in the inland Northwest is the alteration of
disturbance regimes — and the effect of those
changes on vegetation — following Euro-American
settlement. Grazing, timber cutting, fire suppression
and road building have all lead to dramatic shifts in
fire frequency and size. Bork (1994, Ph.D. thesis from
Youngblood et al. 2004) reconstructed a landscape
scale fire history in eastern Oregon over the past 619
years and found large differences in the number of
fires: between 1700-1800, 48 fires; between 18001900, 41 fires; the next 80 years, 17 fires. The
reduction in the number of fires resulted in stands
becoming much more homogenous across the
landscape; ingrowth of shade tolerant, but fire
intolerant trees created greater horizontal and vertical
complexity than under pre-settlement disturbance
conditions (Fry & Stevens 2006; Reynolds & Hessburg
2005; Wright & Agee 2004; Youngblood et al. 2004;
Agee 2003; Hessburg & Agee 2003; Hessburg et al.
2005; Antos & Parish 2002).
Fire exclusion by grazing that removed the fine fuels by
which fires spread and then outright suppression has
also changed fire behavior and thus vegetation
patterns. Recent fires typically burn under more
extreme weather conditions that prevent firefighters
Later-successional patches within this kind of matrix
experienced less frequent fires; Camp et al. (1997)
refer to these patches as fire refugia and their research
found that these patches occurred mostly on northerly
aspects, at stream confluences, and on benches or
headwalls. They found that such patches were
relatively small (well under 100 acres) and spatially
discreet. Their research also indicates that late
successional fire refugia almost never occurred on
southerly aspects, but they did find that fire
suppression, especially in combination with selective
harvesting resulted in young forests with similar latesuccessional attributes as historical fire refugia.
These structurally complex forests occurred on all
aspects, not only in areas that supported historical fire
refugia. Other research confirms these results: Spies et
al. (2006) noted that fire exclusion has resulted in
stands that are much more complex, with shadetolerant associates becoming considerably more
prevalent. Structurally complex forests are susceptible
to high severity fires because, as noted above, fires
now occur only under extreme weather conditions that
preclude suppression. Under such weather
Yale University’s Global Institute of Sustainable Forestry
conditions, fires burning in these forests would likely
be stand replacing
In summary, where the historical disturbance regime
was one where fires were relatively frequent and
generally low severity, old growth forests were
dominated by fire tolerant species. Forests were
structurally less complex but individual trees could
persist for centuries and attain large diameters.
Species complexity would have been found in the
understory grasses, forbs, and shrubs. Late
successional old growth occurred on sites that under
most conditions did not burn, allowing the structural
complexity associated with the growth of shade
tolerant (but fire intolerant) trees. Structural complexity
was also possible on very poor sites where fire severity
was low because of the absence of a continuous
fuelbed.
Habitat Characteristics
Another factor often considered when discussing oldgrowth is the habitat characteristics and value of the
stand. This is particularly evident when considering the
repercussions of the Northwest Forest Plan. One of the
main goals of the plan is the “maintenance and/or
creation of a connected or interactive old-growth forest
ecosystem...” within the range of the Northern Spotted
Owl (Strix occidentalis caurina) (USDA 1994). This
goal, perhaps inadvertently, resulted in owl presence
sometimes used as a surrogate for old growth (Camp,
pers. obs.).
In general, owl habitat is congruent with forests having
late-successional attributes, whether those forests are
historical fire refugia or younger structurally complex
forests resulting from fire exclusion. Spies et al. (2006)
highlight a potential conflict with the objective of the
Northwest Forest Plan to preserve old-growth for the
owl in inland Pacific northwestern forests. Traditional
park-like, open old growth stands associated with presettlement fire regimes are not suitable habitat for the
owl. Because of this, old growth strategies in areas
covered by the Northwest Forest Plan tend toward
protection of structurally complex forests – whether or
not they are old. Lee & Irwin (2005) studied effects of
fuel reduction treatments on spotted owl habitat in the
southern Sierra Nevada and concluded that moderate
9
fuel treatments did not reduce canopy cover to levels
thought to negatively impact the species. The difficulty
with using metrics such as owl habitat as an indicator
for old-growth is essentially twofold: (1) habitat
characteristics may be more consistent with structural
diversity than stand age or successional state and,
perhaps more importantly in inland forests, (2) this
method of characterizing old growth does not take into
account the inherent disturbance regime and resulting
vegetation conditions associated with the region.
Scale
Spatial scale and landscape pattern are often
highlighted as important considerations in the
characterization of old-growth. While actual research at
the landscape scale seems to be only in the early
stages, the need for such work is often discussed
(Spies et al, 2006; D’eon & Glenn 2005; WSDNR
2005; Franklin & Van Pelt 2004; Helms 2004; Spies
2004; Agee 2003; Franklin et al. 2002). The
presumption is that old-growth is part of a spatial
mosaic across the landscape. It is not only the
presence of individual large, old trees, but an
assortment of old-growth dominated stands among a
larger mosaic of differing stand development
processes.
According to Spies et al. (2006), old-growth
ecosystems are really a mosaic phenomenon, given
the complexity of the system and spatial dependence
of processes such as insect herbivory, regeneration
and fire. The grain of this mosaic varies considerably
depending on developmental processes and
disturbance regimes. In inland northwestern forests
dominated by patchy fires, the spatial grain may be
relatively fine (1-10+ acres) (WSDNR, 2005), while on
sites with infrequent disturbance, such as wetter sites
and forests under fire suppression, the grain is often
much coarser. These scientists postulate that
understanding the spatial relationship and patch
dynamics across the landscape is critical to any
definition of old-growth. “Old” will be relative to the
landscape mosaic.
A growing number of researchers are looking at
landscape level interactions and patch dynamics in
interior northwestern forests (D’eon & Glenn 2005;
10
Scientific Basis for Forest Management in the U.S. Inland West
Boyden et al. 2005; Youngblood et al. 2004). Often
these studies attempt to quantify spatial and temporal
patterns using pre-established metrics (i.e. Ripley’s K
function). D’eon & Glenn (2005) compared the
geometry of forest patches in southeastern BC,
comparing landscape pattern and fragmentation
between harvested areas and old-growth/ recent
wildfire patches. Their research attempted to answer
two basic questions: (1) is harvesting fragmenting the
existing forest pattern and (2) is harvesting imposing a
different, more fragmented pattern across the
landscape? Their results did not coincide with their
predicted fragmentation patterns and warrant further
research. Old growth was characterized using only age
class thresholds (> 140 yrs for interior cedar hemlock
dry warm stands and >250 for other stand types).
Other methods of defining old growth would probably
achieve different results and perhaps more insight into
the usefulness of fragmentation metrics for
understanding old growth at the landscape scale.
ha. Average canopy dominant diameter ranged from
59 to 61 cm dbh and trees were spatially aggregated.
For managers desiring to replicate historical stand
structure, this research provides abundant reference
points. Their results also could be used to develop
attribute thresholds for identifying ponderosa pine
dominated old growth forests in the inland Pacific
Northwest.
Youngblood et al. (2004) also considered spatial
pattern as one of many characteristics in a rigorous
analysis of old growth ponderosa pine forests. Using
data from long term re-measured plots, they developed
detailed descriptions of the structural attributes of
these forest stands by addressing four basic questions:
(1) What diameter distributions were historically (pre1900) present; (2) What were the historical ranges of
tree densities in these stands; (3) Were the spatial
patterns of trees similar in these old-growth ponderosa
pine stands; and (4) How can this information be
applied to support management of eastside ponderosa
pine stands? Although the study was not designed to
detect discreet age classes, Youngblood et al. (2004)
found high heterogeneity with respect to age. Some
recruitment has occurred in every decade since 1850,
possibly as a result of a gradual warming of the climate
following the Little Ice Age and the above-normal
precipitation that occurred between 1885 and 1910
(sensu Garfin and Hughes 1996). Recruitment before
1850 was “increasingly infrequent” with a long gap
between 1800 and 1850 but a greater representation
of trees recruited during the period 1670-1700.
Establishment at three separate sites was consistent,
suggesting a strong climatic influence. This study
found similar historical overstory tree densities as
recent research in ponderosa pine forests elsewhere
(47-53 trees per ha). Snag densities were about 9 per
A recurring theme and one of the most publishedabout topics in the literature about old growth in the
inland Pacific Northwest is the concept of historic
range of variability (HRV). This concept is also referred
to as “natural range of variability” (NRV) and is tied to
the expected pattern of vegetation that would arise
from the inherent disturbance regime of the region.
There is considerable discussion about how landscape
dynamics
changed
following
euro-American
settlement. Much of the current research focuses on
the pre-settlement conditions of the drier forest types
(Fry & Stevens 2006; Reynolds & Hessburg 2005;
Wright & Agee 2004; Youngblood et al. 2004; Agee
2003; Hessburg & Agee 2003; Hessburg et al. 2005;
Antos & Parish 2002; ). The methods behind these
reconstructions vary from detailed site analysis
(Youngblood et al. 2004) to reviews of historical
accounts of past conditions (i.e. Bonnicksen 2000).
While the research of Youngblood et al. (2004)
provides excellent and sorely needed baseline data
about one type of interior northwestern old growth,
replication of this type of study is critically needed for
developing attribute thresholds for other varieties of old
growth, especially those with late successional
characteristics.
Historic Range of Variability: How has the
region changed?
Some of the more recent studies rely on remote
sensing (i.e. Hessburg et al. 2005) and must be
interpreted carefully, as the tools currently used to
determine old-growth remotely are still somewhat
crude. Norheim (1998) compared two remote sensing
techniques for determining old-growth and found
significant differences. While identifying sites
containing large trees is possible using aerial and even
satellite photography, it is difficult to discern if the size
Yale University’s Global Institute of Sustainable Forestry
of the trees is related to their ages or to site
productivity.
Overall, the majority of recent literature regarding oldgrowth in the inland Pacific Northwest has been
directed towards understanding past forest conditions.
The focus seems to indicate using past conditions as
a reference point for determining healthy old-growth
stands. This is, of course, a human construct based
on viewing pre-human influence as the appropriate
state of forest health. This may indeed be a useful
metric as much attention has been paid to the high
risk and consequences of large-scale fires resulting
from changing conditions within the region. But much
more research is required to fully understand the
structure and function of eastside forests, particularly
considering the altered landscape post-settlement and
fire exclusion.
Spies et al. (2006) summarize what is known about
old growth forest conditions in the inland Pacific
Northwest:
1. These forests exhibited a high degree of
compositional
diversity
and
spatial
heterogeneity at stand, landscape, and
regional scales as a result of variation in flora,
climate, topography, and disturbance.
2. Insects and diseases played an important role
in forest development and interacted with the
primary disturbance, fire.
3. In dry forests, topography had stronger
influence on species composition and fire
regimes than it did in more mesic forests.
4. Under historical disturbance regimes a large
portion of these landscapes would have been
covered by a fairly fine-grained mosaic of
relatively open, old-growth forest.
5. Dense, multistoried, old-forest conditions did
occur under the inherent fire regime, but
these forests were primarily restricted to
particular topographic situations and, within
the ponderosa pine and dry mixed conifer
types, were relatively ephemeral.
6. Under mixed severity regimes, such as in
southwestern Oregon and northern California,
multi-canopied old growth was somewhat
more common.
7. The rate of understory development and fuel
accumulation increases with decreasing
moisture stress from ponderosa pine to
mixed-evergreen forest types.
8.
Distribution of large woody debris is patchy
and accumulations are less than in moist oldgrowth forests west of the Cascades crest.
9.
Variation in tree species composition led to
differences in disturbance severity and forest
response to disturbance. For example, the
presence of hardwoods within otherwise
coniferous forests in the Kalamath region
possibly reduced fire severity; following fire,
hardwoods can re-establish rapidly by
sprouting.
10. The diversity of old-growth forest within and
among stands has been lost as a result of
excluding fire and from recent high-severity
fires. Shade-tolerant understory species have
encroached in the formerly open areas
between dominant trees, creating ladder fuels
that carry fires into the crowns of otherwise
fire tolerant large ponderosa pines and
Douglas-fir. High severity fires in these dense
stands will potentially result in more uniform
postfire stands.
11
12
Scientific Basis for Forest Management in the U.S. Inland West
Agee, J.K. 1993. Fire Ecology of the Pacific Northwest
Forests. Island Press, Washington, D.C.
Agee, J.K. 2003. Historical Range of Variability in
Eastern Cascades Forests, Washington, USA.
Landscape Ecology, 18, 725-740.
Antos, J.A. and Parish, R. 2002. Dynamics of an OldGrowth, Fire-Initiated, Subalpine Forest in Southern
Interior British Columbia: Tree Size, Age, and Spatial
Structure. Canadian Journal of Forest Research, 32,
1935-1946.
Arsenault, A. 2003. A Note on the Ecology and
Management of Old-Growth Forests in the Montane
Cordillera. Forestry Chronicle, 79, 441-454.
Bonnicksen, T. 2000. America’s Ancient Forests John
Wiley & Sons, Inc., New York.
Boyden, S., Binkley, D., and Shepperd, W. 2005. Spatial
and Temporal Patterns in Structure, Regeneration,
and Mortality of an Old-Growth Ponderosa Pine
Forest in the Colorado Front Range. Forest Ecology
and Management, 219, 43-55.
Camp, A., Oliver, C., Hessburg, P., and Everett, R.
1997. Predicting Late-Successional Fire Refugia
Pre-Dating European Settlement in the Wenatchee
Mountains. Forest Ecology and Management, 95,
63-77.
DeLong, S.C., and W.B. Kessler. 2000. Ecological
characteristics of mature forest remnants left by
wildfire. Forest Ecology and Management 131(1-3):
93-106.
D’Eon, R.G. and Glenn, S.M. 2005. The Influence of
Forest Harvesting on Landscape Spatial Patterns
and Old-Growth-Forest Fragmentation in Southeast
British Columbia. Landscape Ecology, 20, 19-33.
Franklin, J.F. and Van Pelt, R. 2004. Spatial Aspects of
Structural Complexity in Old-Growth Forests.
Journal of Forestry, 102, 22-29.
Franklin, J.F., Spies, T.A., Van Pelt, R., Carey, A.B.,
Thornburgh, D.A., Berg, D.R., Lindenmayer, D.B.,
Harmon, M.E., Keeton, W.S., Shaw, D.C., Bible, K.,
and Chen, J. 2002. Disturbances and Structural
Development of Natural Forest Ecosystems with
Silvicultural Implications, Using Douglas-fir Forests
as an Example. Forest Ecology & Management,
155, 399-423.
Franklin, Jerry F. and Dyrness C.T. 1988. Natural
vegetation of Oregon and Washington. Corvallis, OR:
Oregon State University Press.
Frelich, Lee E. and Peter B. Reich. 2003. Perspectives
on development of definitions and values related to
old growth forests. Environmental Review 11: S9S22.
Fry, D.L. and Stephens, S.L. 2006. Influence of
Humans and Climate on the Fire History of a
Ponderosa Pine-Mixed Conifer Forest in the
Southeastern Klamath Mountains, California. Forest
Ecology and Management, 223, 428-438.
Garfin, G.M. and M.K. Hughes, 1996. “Eastern Oregon
Divisional Precipitation and Palmer Drought Severity
Index from Tree-Rings.” Report to the U.S. Forest
Service Intermountain Research Station. USDA
Forest Service Cooperative Agreement PNW 90174.
Gray, R.W., E. Riccius and C. Wong. Undated.
Comparison of Current and Historic Stand Structure
in Two IDFdm2 Sites in the Rocky Mountain Trench.
R.W. Gray Consulting, LTD.
Helms, J.A. 2004. Old-Growth: What Is It? Journal of
Forestry, 102, 8-13.
Hessburg, P.F., Smith, B.G., Kreiter, S.G., Miller, C.A.,
Salter, R.B., McNicholl, Ch.H., and Hann, W.J.
1999. Historical and current forest and range
landscapes in the Interior Columbia River Basin and
portions of the Klamath and Great Basins. Part 1.
Linking vegetation patterns and landscape
vulnerability to potential insect and pathogen
disturbances. Gen. Tech. Rep. PNW-GTR-458.
USDA For. Serv., Pacific Northwest Res. Sta.
Portland, OR 357 pp.
Yale University’s Global Institute of Sustainable Forestry
Hessburg, P.F., Smith, B.G., Slater, R.B., Ottmar, R.d.,
and Vlvarado, E. 2000. Recent changes (1930s1990s) in spatial patterns of interior northwest
forests. USA. Forest Ecology and Management 136:
53-83.
Hessburg, P.F. and Agee, J.K. 2003. An Environmental
Narrative of Inland Northwest United States Forests,
1800-2000. Forest Ecology and Management, 178,
23-59.
Hessburg, P.F., Agee, J.K., and Franklin, J.F. 2005.
Dry Forests and Wildland Fires of the Inland
Northwest USA: Contrasting the Landscape Ecology
of the Pre-Settlement and Modern Eras. Forest
Ecology and Management, 211, 117-139.
Hopkins, B., Simon, S., Schafer, M., and Lillybridge,
T., 1992(a). Interim old growth definition for grand
fir/white fir series. USFS Region 6. Portland, OR.
Hopkins, B., Simon, S., Schafer, M., and Lillybridge, T.,
1992(b). Interim old growth definition for ponderosa
pine series. USFS Region 6. Portland, OR.
Lee, D.C. and Irwin, L.L. 2005. Assessing risks to
spotted owls from forest thinning in fire-adapted
forests of the western United States. Forest Ecology
And Management, 211, 191-209.
Lund, H.G. 2005. Definitions of Old Growth, Pristine,
Climax,
Ancient
Forests,
Degradation,
Desertification, Forest Fragmentation, and Similar
Terms., Vol. 2006. Website-Forest Information
Services.
MacKinnon, A. and Vold, T. 1998. Old-Growth Forests
Inventory for British Columbia, Canada. Natural
Areas Journal, 18, 309-318.
Mosseler, A., Thompson, I., & Pendrel, B.A. (2003)
Overview of Old-Growth Forests in Canada from a
Science Perspective. Environmental Reviews, 11.
13
Norheim, Robert A. 1998. Why so different? Examining
the techniques used in two old growth mapping
projects. In Sensing and Managing the
Environment: Proceedings, 1998 International
Geoscience and Remote Sensing Symposium
(IGARSS ‘98). Institute of Electrical and Electronics
Engineers, Seattle. Vol. 3, pp. 1620-1622.
Ohlson, T.H. 1996. Fire regimes of the ponderosa pine
– Douglas-fir/beardless bluebunch wheatgrass plant
association in the Methow Valley of north central
Washington. MS thesis. Washington State
University. 87 p.
Perry, D., Henjum, M., Karr, J., Bottom, J., Bendarz,
S., Wright, S., Beckwitt, S., & Beckwitt, E. (1995)
Interim Protection for Late-Successional Forests,
Fisheries, and Watersheds: A Summary of the
Report of the Eastside Forests Scientific Society
Panel 103-114 in Symposium proceedings,
Ecosystem Management in Western Interior Forests.
Dept. of Natural Resources, Washington State
University, Pullman, WA.
Reynolds, K.M. and Hessburg, P.F. 2005. Decision
Support for Integrated Landscape Evaluation and
Restoration Planning. Forest Ecology and
Management, 207, 263, 278.
Schellhaas, R., Camp, Spurbeck, D., and Keenum, D.
2000. Report to the Colville National Forest on the
results of the South Deep watershed fire history
research. USDA Forest Service Pacific Northwest
Research Station Wenatchee Forestry Sciences Lab.
Schellhaas, R., Spurbeck, D., Keenum, D. and
Conway, A. 2003. Report to the Okanogan and
Wenatchee National Forests on the results of the
Twentymile Planning Area fire history research.
USDA Forest Service Pacific Northwest Research
Station Wenatchee Forestry Sciences Lab.
Spies, T.A. 2004. Ecological Concepts and Diversity of
Old-Growth Forests. Journal of Forestry, 102, 14-21.
Spies, T., Hemstrom, M., Youngblood, A., and
Hummel, S. 2006. Conserving old-growth forest
diversity in disturbance prone landscapes.
Conservation Biology, 20, 351-362.
14
Scientific Basis for Forest Management in the U.S. Inland West
USDA (United States Department of Agriculture)
Forest Service and BLM (Bureau of Land
Management) 1994. Record of decision for
amendments to Forest Service and Bureau of Land
Management planning documents within the range
of the Northern Spotted Owl. USDA Forest Service
and BLM, Washington, DC. 74 p.
USFS. 1993. Region 6 Interim Old-Growth Definitions
for the Douglas-fir Series, Grand Fir/White Fir Series,
Interior Douglas-fir Series, Lodgepole Pine Series,
Pacific Silver Fir Series, Ponderosa Pine Series, Port
Orford Cedar Series, Tanoak (Redwood) Series,
Western Hemlock Series. USDA Forest Service,
Pacific Northwest Region, Portland, Oregon.
WSDNR. 2005. Definition and Inventory of Old Growth
Forests on DNR-Managed State Lands. Washington
State Department of Natural Resources. Olympia,
WA.
Wells, R.W., Lertzman, K.P., and Saunders, S.C. 1998.
Old-Growth Definitions for the Forests of British
Columbia, Canada. Natural Areas Journal, 18, 279292.
Williams, C., Smith, B., Mrowka, R., Berube, J., and
Kovalchik, B. 1992. Interim old growth definition for
interior Douglas-fir series. USFS Region 6. Portland,
OR
Wright, C.S. and Agee, J.K. 2004. Fire and Vegetation
History in the Eastern Cascade Mountains,
Washington. Ecological Applications, 14, 443-459.
Youngblood, A. 2001. Old-Growth Forest Structure in
Eastern Oregon and Washington. Northwest
Science, 75, 110-118.
Youngblood, A., Max, T., and Coe, K. 2004. Stand
Structure in Eastside Old-Growth Ponderosa Pine
Forests of Oregon and Northern California. Forest
Ecology and Management, 199, 191-217.
Yale University’s Global Institute of Sustainable Forestry
15
Post-Fire Salvage Logging in Inland Northwest Forests
A Review and Synthesis
Ann E. Camp, Mary L. Tyrrell and Jennifer Karanian
INTRODUCTION
Post-fire management practices in exceptionally fireprone forest ecosystems of the inland northwest differ
greatly with respect to timing and intensity; these
differences are largely a result of forest ownership and
management objectives. Controversy surrounds nearly
all post-fire management practices, including
stabilizing slopes and streams, salvage of burned
trees, and regeneration. A reason often given for this
controversy is the lack of definitive scientific evidence
to support one management alternative over another.
In 2001 McIver and Starr extensively reviewed the
available literature on post-fire salvage logging. They
found 21 studies on the environmental effects of postfire logging worldwide, most of them un-replicated
and/or lacking a control. Although five years have
elapsed since publication of that seminal review, there
has been scant new research on the topic. Peer
reviewed and other published papers typically reframe a subset of the studies reviewed by McIver and
Starr and advocate for or against the practice. This
paper examines the controversy surrounding post-fire
salvage logging and reports on the most recent
scientific evidence addressing its benefits and its
drawbacks. We put forth the differing positions of
eminent scientists, but emphasize results and
conclusions based on published scientific research.
Much of the recent debate over salvage logging
following wildfire results from the primary lens through
which the issue is viewed: ecological versus socio-
economic. Ecological concerns include post-fire
logging effects on soil and hydrology, vegetation
responses, structural changes that may impact wildlife
habitat and site productivity, and interruption of natural
recovery processes. Socio-economic concerns include
loss of timber revenue and monies from other
resources destroyed in the fire, increased fuel levels
that could potentially increase the intensity of a future
fire, and sustainability of local communities that often
are at least partially dependent on commodity
extraction from adjacent forest lands. And the view
through each of these lenses can be supported by
scientific studies. For example, Ice and Beschta
(1999), two eminent hydrologists, co-authored and
presented a paper in which they showed that scientific
evidence could be used to support very different
conclusions regarding, among other topics, the
efficacy of post-fire salvage logging.
It is important to keep in mind that the term “salvage
logging” can refer to an array of operations that have
anywhere from minimal to extensive impacts. There is
little disagreement that harvesting trees killed by
wildfires provides an economic benefit over leaving
them to decay. The debate revolves around if, when,
how, and to what extent, economic benefits can be
derived without causing further damage to the
ecosystem.
16
Scientific Basis for Forest Management in the U.S. Inland West
ECOLOGICAL CONSIDERATIONS
Following a wildfire, whether stand-replacing or lower
severity, critical management decisions must be made
rapidly. While managers can sometimes make
advance preparations where fires are anticipated,
uncertainties will always remain. Even with the
additional knowledge that comes in the fire’s
aftermath, appropriate responses may not be obvious
or undisputed. Nevertheless, decisions must be made
and implemented. There may be narrow windows of
opportunity in which to implement potential response
actions. Scientific evidence and field observations from
seasoned land managers suggest that decisions
regarding post-fire logging require consideration of
several key ecological and economic factors, any of
which may ultimately either justify or rule out the use
of post-fire logging.
Soils and Hydrology
Effects of wildfire on soils vary greatly depending upon
the magnitude and duration of the burn; these factors
are in turn influenced by fuel dynamics, climate and
weather, and topography. The magnitude and
duration of the burn, along with soil moisture content,
directly influence the depth at which soils are
impacted. The deeper into the soil profile the burn,
the more organic matter is consumed and longer
recovery times are likely. Fire magnitude and duration
are also important determinants of alterations in the
physical, structural, chemical, and biotic properties of
soils. Potential changes include the following: clay
particles may fuse into sand-sized particles; soil bulk
density may increase, thereby decreasing total porosity
and water-holding capacity; the formation of water
repellent layers may result from the burning of
resinous vegetation; and shifts may occur in the total
and available site nutrients (Agee 1993).
Some erosion happens naturally in forested
ecosystems, but following fire, erosion and its effects
can be much more severe. By removing vegetation,
fire increases the potential for surface erosion,
including splash, sheet, rill, and gully erosion, frost
heaving, and ravel (soil movement caused by gravity);
mass wasting, which includes avalanche and creep
and is a dominant erosion process in steep
mountainous terrain; and channel erosion (McNabb
and Swanson 1990). Loss of vegetation changes
inputs of solar radiation, impacting regeneration. The
changed reflectance (albedo) of blackened forest
floors results in higher daytime and lower nighttime
temperatures (Agee 1993).
Soil transformations resulting from fire are associated
with changes in hydrological regimes. Fires or other
disturbances can reduce litter and plant cover from as
much as 75% to less than 10%. This increases runoff
by as much as 70%, which increases erosion potential
by three orders of magnitude, thereby negatively
impacting hydrologic conditions (Robichaud et al.
2000). The ash left by incomplete combustion
contains chemicals, especially calcium, magnesium,
and sodium; washed into streams these chemicals can
alter water chemistry and result in nutrient loss from
the ecosystem. Loss of vegetation—including loss of
live trees—affects water quantity and stream
dynamics, since transpiration, infiltration, and
evaporation are reduced (Rieman et al. 2003).
Silvicultural operations—including salvage logging—
also affect the soils and hydrology of the ecosystems.
Understanding the added impacts of logging on the
soils and hydrology of fire-impacted ecosystems is
critical. Will salvage operations increase negative
impacts, counteract the damage, or have little
additional effect? Will salvage result in an entirely new
set of consequences? Jurgensen et al. (1997)
reviewed research on harvesting impacts on inland
northwest soils and cautioned that compaction and/or
removal of organic material may reduce site
productivity. The soils of this region, much of them
derived from volcanic ash, are particularly susceptible
to mechanical displacement. Compaction damage
can persist for decades, particularly when soil moisture
is low.
Certainly, the outcome of post-fire salvage depends on
site conditions and removal method. Sessions et al.
(2004) suggest that properly planned and conducted
post-fire harvesting operations may aid regeneration
by exposing mineral soils. They emphasize the
importance of choosing appropriate harvesting
methods in terms of slope position and site
characteristics. During salvage harvesting measures
Yale University’s Global Institute of Sustainable Forestry
such as contour felling may be implemented,
potentially reducing post-fire erosion as much as 40 to
60 percent (Robichaud et al. 2000). It has also been
suggested that post-fire logging could reduce soil
hydrophobicity by breaking up the impervious layer
(McIver and Starr 2001). It should be noted that soil
hydrophobicity following fire, while problematic in
chaparral, has not been shown to occur widely in the
inland northwest (Agee 1993).
Not all post-fire harvest operations require new roads,
but there is a great deal of concern that building new
road systems into burned areas will exacerbate
ecological damage. Where roads are not present and
site sensitivity, terrain, or other factors precludes
building them, some advocate using cable yarding
systems or helicopters to extract timber. Cable yarding
systems are generally limited in the distance they can
operate from roads to about one-half mile or less
(Sessions et al. 2003). Using helicopters can greatly
increase this distance, but helicopter logging is
expensive, and thus constrained by the value of the
timber extracted. Both cable and helicopter yarding
decrease soil disturbance; some costs associated with
these methods may be offset by reducing or
eliminating costly road building and through rapid
removal of valuable timber before insects, decay, or
depressed prices take their toll (Akay et al. 2006;
McIver and Starr 2001).
Conducting logging operations over organic matter or
snow is also recommended as a means of reducing
erosion and compaction. Whether derived from
logging slash or needle fall, a substantial organic layer
helps protect vulnerable soils (Jurgensen et al. 1997;
McIver and Starr 2001). Studies show, too, that tractor
skidding over snow rather than bare soils reduces the
extent of severe soil disturbance by more than half
(McIver and Starr 2001).
Vegetation
Many plant species in inland northwestern forests are
to some extent adapted to fire. These adaptations
include dormant seed banks, rapid early growth,
fire-resistant foliage or bark, adventitious buds,
lignotubers, or serotinous cones (Agee 1993). Concern
exists that post-fire logging may interfere with these
processes or adversely impact natural regeneration.
17
Hanson and Stuart (2005) examined forest edges 14
years after a large wildfire in the Klamath Mountains to
determine, in part, if regenerating vegetation patterns
differed at the fire’s edge in places where salvage
logging occurred and where it had not. Salvaged areas,
unfortunately, were broadcast burned following
logging, making it impossible to determine if the results
reported in this study resulted from logging, reburning, or an interaction. The authors reported that
salvage logging “significantly altered plant composition
and structure of the edge environment,” including
lower species diversity and richness, higher hardwood
cover, lower shrub cover (particularly nitrogen-fixing
species), more invasive species, and statistically
significant differences in overall species composition.
These results are similar in the short term to those of
an earlier study by Stuart et al. (1993); however, Stuart
et al. reported that effects of salvage decreased over
time and in some cases may have resulted in some
ecological benefits, including site domination by
hardwoods. While the initial domination of a site by
hardwoods is often regarded as detrimental from a
timber-growing perspective, the ecological benefits for
wildlife habitat and ecosystem function—including
nutrient cycling—have been well-documented.
Conversely, Stuart et al. suggest that soil productivity
may have increased in unsalvaged sites as a result of
initial dominance by nitrogen-fixing shrubs. Both
studies suffer from a design that does not permit
salvage effects to be determined independently from
post-salvage site treatment.
Donato et al. (2006) reported that salvage logging
following the 2002 Biscuit Fire in Oregon reduced
natural conifer regeneration by 71% (to 224 seedlings
per ha) as a result of soil disturbance and physical
burial by woody material. This study, appearing in the
journal Science, has been given much scrutiny by the
press and highlights problems associated with making
policy decisions based on a few selected studies or on
short-term research results. Indeed, the Donato paper
was published prior to the conclusion of the study and
omitted pertinent information about the study sites that
would ordinarily be included in research of this nature.
Much of the criticism of this paper was directed at the
authors’ conclusions that “post-fire logging can be
counterproductive to goals of forest regeneration and
fuel reduction.” The study was conducted two years
18
Scientific Basis for Forest Management in the U.S. Inland West
after the fire, which is not enough time to test this
hypothesis. Longer-term research would be needed,
particularly on regeneration success. Also, Donato’s
research focused on conifer regeneration; there is no
mention of other vegetation either harmed or helped
by logging operations, nor the potential for recruitment
of new conifer seedlings following salvage.
Nevertheless, the results are a useful addition to the
data on post-fire treatment and short-term
regeneration of species of economic interest.
Beschta et al. (2004) state that post-fire logging
damage to early successional species, particularly
nitrogen-fixing plants, can disrupt nutrient
replenishment. Stuart et al. (1993) reported loss of
nitrogen-fixing shrubs on logged sites; however, many
nitrogen-fixing vascular plants are adapted to
disturbance and can rapidly colonize disturbed areas
whether the disturbance is a fire or a logging operation.
Some have suggested that negative effects of
harvesting on natural regeneration could be
ameliorated to some extent by harvesting before
natural regeneration begins to occur (Kolb Testimony
2006; McIver and Starr 2001).
In addition to salvage effects on regeneration, concern
exists that post-fire logging may damage remaining live
trees. Potential post-fire damage varies by harvesting
method and the composition and structure of the
burned stand; it seems unlikely that such damage
would differ significantly from harvesting in similar,
unburned forests. We found no studies on the effect of
post-fire salvage on residual trees. However, some
recent research exists on fuel reduction treatments
and their impacts on residual trees.
In mixed conifer stands in northeastern Oregon,
McIver et al. (2003) found little difference in damage
to residual trees between forwarder and skyline yarded
units; true firs (Abies spp.) sustained slightly more
damage
than
non-fir
species
(Douglas-fir
(Pseudotsuga menziesii), larch (Larix occidenatlis),
lodgepole pine (Pinus contorta) or Engelmann spruce
(Picea engelmanii)). On average, about 34% of the
residual trees sustained some bole damage; mean
wound size per tree was about 240 cm2. Wounding
was defined as removal of bark with exposure or
destruction of cambial tissue. In their discussion, the
authors suggested that the amount and type of
damage might increase stem decay and, where
extensive, contribute to increases in bark beetle
populations. In a similar study, Camp (2002)
compared four different harvesting systems used to
thin dense, small-diameter stands in northeastern
Washington and found that, in general, cut-to-length
processing caused less damage to the residual stand
than whole-tree harvest and skyline yarding was less
damaging than forwarder yarding. It should be noted
that such stands may not be the first choice for salvage
following fire, given their marginal economic value
even when trees are not fire-killed.
Structural Changes and Wildlife
Wildfire can impact the forest structure in ways that
may be beneficial to ecosystem functioning; for
example, by consuming fuels, fires can promote
establishment of new seedlings or reduce populations
of invasive species or native defoliators and bark
beetles. On the other hand, structural changes that
result from wildfires can reduce the quality of habitat
for some species of wildlife. Loss of vegetation in
riparian areas can increase water temperatures and
sediment loads, detrimental to some fish species.
Rieman et al. (2003) opine that the majority of fish
species in the inland northwest are listed or being
considered for listing as endangered, with many
species now restricted to small, isolated remnants of
their former ranges. The authors suggest that
management activities may contribute to further
degradation of fish habitat, but were primarily
addressing harvesting to reduce fuel loads. Minshall
(2003) suggests the same is true for stream
macroinvertebrates; fires may not be detrimental to
productive and undisturbed aquatic ecosystems, but
will cause more severe effects on adversely impacted
systems. He further suggests that post-fire harvesting
should remove no more than 25% of merchantable
timber, that harvests be spread across the landscape,
and their size be in proportion to the size classes of
trees present at the time of the fire.
Structural changes from fire and post-fire
management also impact bird and mammal
populations. Many bird species are dependant on
standing, dead trees (snags) for nesting and/or feeding
Yale University’s Global Institute of Sustainable Forestry
habitat. While one goal of post-fire salvage is removal
of fire-killed timber before it decays, these are precisely
the trees that could eventually provide habitat for
cavity-nesters.
Studies on snag use by cavity-nesting birds in postfire
landscapes reveal that different species use different
stand structures. Saab et al. (2002) found that blackbacked woodpeckers preferred stands of densely
spaced Douglas-fir snags, while Haggard and Gaines
(2001) report that Lewis’s woodpeckers and western
bluebirds selected stands having medium and low
snag densities. They also determined that the size
distribution of snags and the presence of trees with
broken tops that allow decay fungi to infect the tree
influenced bird species composition. They
recommended leaving a range of snag densities, size
classes, and spatial arrangements across burned
landscapes to maintain a diversity of habitat types and
species.
A prevalent argument favoring salvage logging
following fire is that the burned stand could become a
focus for an outbreak of insects. Sessions et al. state
that “the largest numbers of fire-stressed trees are
likely to be infested [by insects] in the year after a fire”
(2004). This topic is covered in much greater detail in
Kramme et al. (2006) review of insects and their
management in inland northwest forests, and will not
be treated further herein.
McIver and Starr (2001) discuss earlier studies on the
post-fire logging effects on wildlife. These studies
indicate that the fire itself has a significant impact on
wildlife species, and that postfire logging may enhance
the change or delay recovery.
An important
consideration for forest managers is how wildlife
species compositions changed over the period of fire
exclusion and suppression. Wildlife communities in
inland western forests that developed in the absence
of fire may well be negatively impacted by fire and
subsequent salvage harvesting. These wildlife
communities may be quite different from those that
existed prior to fire suppression.
19
Coarse Woody Debris
Proponents of salvage logging frequently cite that
burned-over forests contain high amounts of dead
fuels, increasing their susceptibility to a second, more
catastrophic fire. Sessions et al. (2004) estimated that
post-fire woody debris on a portion of the 2002 Biscuit
Fire would leave the landscape vulnerable to intense
wildfires for at least 60 years, based on a model of
snag and log decay. Donato et al. (2006) also
conducted research within the perimeter of the Biscuit
Fire and noted greatly increased fuel loads following
salvage operations because of unmerchantable
material left behind. Salvage does tend to temporarily
increase the proportion of fine fuels that can carry
fires, as it is the larger fuels that are usually targeted for
removal. McIver et al. (2003) found that fuel reduction
treatments in unburned stands in northeastern Oregon
resulted in a temporary increase in fine fuels; however,
removal of a portion of the stand lowered overall fuel
amounts and greatly reduced the potential for fires to
crown out.
There has been much rhetoric about the potential for
an initial burn to create conditions for a second, more
catastrophic fire. Funds were allocated to study this
phenomenon—including any effects from salvage
logging—after several particularly large fires that
burned parts of eastern Washington and Idaho in 1994
(Camp, personal observation). The research was
started at the United States Forest Service Pacific
Northwest Research Station lab in Wenatchee, WA, but
not completed.
A study of this sort is difficult to implement for several
reasons. Older fires (the initial burn) had poorly
mapped perimeters making it difficult to determine
what had burned once versus twice. The elapsed time
between subsequent fires was a confounding factor. It
is likely that there will be great differences between two
successive fires in ten years versus two successive
fires in 50 years. It was also difficult to find areas where
there had been two successive burns and where, on
the initial burn, there were areas with and without postfire salvage logging. While the rhetoric rages, the
science is inadequate to support either position.
20
Scientific Basis for Forest Management in the U.S. Inland West
Where fire managers see fuels, wildlife biologists see
habitat. Snags provide important habitat. Fallen large
woody debris (LWD) also provides food, shelter, and
protection for invertebrates, mammals, reptiles, and
amphibians; improves rearing habitat and cover for
anadromous fish; and provides nutrients for many
aquatic species (Brown et al. 2003). In addition to the
myriad benefits to wildlife, LWD is important to nutrient
cycling functions. According to Jurgensen et al.
(1997), LWD can provide up to 50% of the total
nitrogen fixed in forest ecosystems. Many nutrients
present in wood are not volatilized by fire, remaining in
snags and logs and becoming available to plants as
these decay (National Research Council 2000). On
the other hand, LWD can have negative impacts other
than as fuel for a future fire. Brown et al. (2003) warns
that an overabundance of LWD can “block fish
passage, cover important spawning sites, and damage
aquatic habitat during postfire flooding events.”
Natural Processes
Many ecosystem components affected by wildfire are
interconnected. The soils, hydrology, vegetation, and
wildlife of a given site ultimately determine the health
and proper functioning of the ecosystem as a whole,
and the wood removed or left on that site is inextricably
linked to the condition of each component. It has
been argued that ecosystems recovering from a
significant disturbance such as fire have sustained
such damage that further human intervention will
worsen the damage and significantly delay recovery
(Beschta et al. 1995). In forests such as those of the
inland west, where disturbance has been an important
component of ecosystem renewal and succession,
salvaging activities may “undermine many of the
ecosystem benefits of major disturbances”
(Lindenmayer et el. 2004). Many argue that where
large disturbances have shaped the landscape for
centuries, natural processes have evolved to recover
from them. It can also be argued (Ice and Beschta
1999) that consequences of prior human
disturbances, including fire exclusion, may have
permanently altered ecosystem recovery processes.
Temporal scales required for allowing natural
processes to reshape ecosystems may be too long
while the short-term impacts of doing so may include
results that are unfavorable from management or
socio-economic perspectives.
SOCIO-ECONOMIC CONSIDERATIONS
Further complicating the ecological considerations in
post-fire environments are the socio-economic factors.
Some of these are a function of different ownerships
and management goals, others are based on deeply
held beliefs and fears.
Financial gains from harvest
Post-fire harvesting of dead trees to recoup economic
value has been standard practice on federal lands in
the west for over 40 years (McIver and Starr 2001).
Since the creation of the Northwest Forest Plan in
1994, all harvesting, including post-fire salvage, has
slowed considerably, in part because of concerns
about soil and water quality (Akay et al. 2006). A
primary objective of post-fire salvage is to extract
merchantable material before it begins to deteriorate
from insects and decay. Sessions et al. (2004) argue
that revenue from post-fire salvage can contribute to
forest restoration, future fire suppression, and future
helicopter stand maintenance operations, while
providing short-term employment opportunities.
Sessions et al. (2003) estimated that returns from firekilled timber on non-wilderness portions of the 2002
Biscuit Fire could yield $100 million or more. In some
instances, ecological and economic costs of postfire
logging are intricately linked. For example, costs
associated with ground-based harvesting systems
increase with distance from roads. Road installation
may allow easier access but can increase erosion and
compaction and, when new roads must be
constructed, delay harvesting.
Timing
A commonly cited economic concern for post-fire
salvage logging is the consequence of delay. Sessions
et al. (2003) warn that the costs of delay are extreme,
providing an estimate of a 22% loss with a one year
delay and “only the butt logs of the largest and most
resistant trees retaining value after five years.” They
point out that, on public lands, timber sale preparation
procedures usually take up to two years to complete,
by which time fire-killed trees will have lost more than
40% of their value. A small administrative study carried
Yale University’s Global Institute of Sustainable Forestry
out on the Wenatchee National Forest following the 1994
Tyee and Rat Creek fires showed that for 25 randomly
selected trees harvested three years following the fires,
all had been attacked by tree-boring insects and were
stained by decay-causing fungi; 72% were decayed and
96% had cracks and checks that markedly lowered the
value of the wood (Hadfield, 1988).
Akay et al. (2006) conclude that harvesting must be
carried out promptly to recover maximum volume and
value of the timber, and that strategies should be
developed that prioritize salvage areas on a landscape
level based on species, diameter, product values,
yarding distances, and available yarding capacity.
With such a plan in place before fires occur, significant
time can be saved and economic losses minimized.
Future fires
Preventing or lessening the impact of future fires is an
economic as well as an ecological concern for forest
managers. The economic importance is particularly
evident in the wildland-urban interface where wildfires
threaten individuals and human structures (McIver et al.
2003). Costs of controlling any wildfire can be
staggering, with fuel reduction treatments sometimes
employed to minimize those costs. Suppression efforts
associated with the 1994 Hatchery Creek, Round
Mountain, Tyee Creek, and Rat Creek fires in central
Washington cost over $69 million; more than 100 homes
and structures were destroyed (Carroll et al. 2000).
Other impacts can far outweigh suppression costs. It
was estimated that the direct economic impacts of the
Biscuit fire that burned almost half a million acres in
Oregon and California in 2002 were around $325
million. This was over and above the $150 million fire
suppression costs (Morton et al. 2003). Whether or not
salvage logging can prevent or lessen impacts from a
future fire, those living within the perimeter of a burn are
generally aware of and concerned about increases of
dead fuels following wildfires.
21
DETERMINING THE APPROPRIATENESS OF
POST-FIRE HARVESTS
Implementation of post-fire logging requires careful
planning and consideration of ecological and
economic factors. The scientific evidence for or against
salvage logging is woefully inadequate; nevertheless
there will be instances where management objectives
or other considerations favor its use. While opponents
of post-fire salvage argue the potential negative
consequences, it should be pointed out that doing
nothing is not without consequences, including
negative ones. Salvage logging may in some instances
be warranted to prevent insect and pathogen invasions
or to reduce the likelihood of future fires—although
additional research is required to confirm the efficacy
of salvage logging toward meeting these objectives.
Deciding on appropriate post-fire management
strategies—including salvage logging—requires
understanding the natural history of the site, its prefire conditions, its short- and long-term management
goals, and its socio-economic context. Given the
dearth of consensus on when, where, and how postfire salvage should occur, there are some guidelines
for its implementation that have wide acceptance:
Minimize soil erosion and compaction
Create favorable conditions for regeneration and
survival of native plant species having economic
and ecological value
Maintain a diversity of habitat types for wildlife
Maintain or improve postfire water quality
Site Conditions
Throughout most of the inland northwest, fire has
shaped ecosystems for thousands of years; humans
have managed forests and fires for hundreds of years.
Pre-European settlement conditions were to greater or
lesser extents the result of Native American
management practices, including use of fire to pattern
landscapes to suit their needs. Returning to presettlement conditions may not be realistic where
human management undertaken since the aftermath
of the Little Ice Age has greatly altered ecosystem
composition and structure. Managers must consider
how the system has changed and how it is likely to be
22
Scientific Basis for Forest Management in the U.S. Inland West
impacted by different management decisions.
Successful post-fire management depends to a great
extent on appropriate pre-fire management.
There may be sensitive areas to consider when
managing post-fire landscapes, which may have
responded differently to the fire and could likewise
differ in response to post-fire management. Riparian
areas, for example, may have similar or very different
fire histories and recovery mechanisms from adjacent
upland areas. There are mixed results from studies
looking at the behavior and effects of fires in riparian
versus adjacent uplands, with some research
documenting that fires have tended to burn less
frequently and at lower severities in riparian areas
(Dwire and Kauffman 2003) while others have shown
no such differences (Schellhaas et al. 2000). Other
sensitive sites may include those that supported rare or
endangered habitats prior to burning. It is not always
possible to determine if management will retard or
hasten the recovery of these areas, indicating that
caution is needed. Monitoring treatment results is
critical to further our understanding and inform future
management decisions.
Future of the Site
Short- and long-term management objectives will often
dictate appropriate post-fire management. Recovery
of economic loss may not be as important on public
lands, although it cannot be categorically ruled out,
especially if monies generated from salvage are used
for remediating other forest values destroyed by fire.
What is important, both prior to and following fire, is
consideration and planning for disturbance through
the application of appropriate silvicultural systems.
Following fire, the importance of sound silvicultural
practices increases because of the greater vulnerability
of the ecosystem (Jain pers. comm. 2006).
Society and the Economy
Public interest in wildfire management is extremely
high. Loss of homes, views, revenue, watershed
values (including municipal water supply), wildlife
habitat, and wilderness values are important and often
contentious societal issues that managers must
address when considering and implementing post-fire
management plans. In their detailed assessment of the
social response to the 1994 fires in central
Washington, Carroll et al. (2000) addressed the issue
of whether residents believed post-fire salvage logging
should occur, and if so, to what extent. They found
widely varying opinions and a great deal of tension
among different segments of the affected community,
mostly concerning the use of burned trees, forest
health and desired future conditions, and silvicultural
practices.
Four broad stakeholder groups emerged:
environmentalists, multiple-use proponents, privateproperty rights and home rule advocates, and wise use
adherents (Carroll et al. 2000). Their political views
and whether they saw biological, physical, and
chemical structures in the environment as ecosystem
elements or resources colored their beliefs about postfire forest management.
Within the environmental community people differed
with respect to the desirability of post-fire management
(including salvage), with some advocating a hands-off,
nature knows best approach and others favoring a
light-handed management approach toward restoring
plant and animal communities more rapidly. Private
property / home rule advocates were primarily
concerned about resisting any and all government
interference on the management of private lands.
Multiple use advocates saw humans as a part of the
natural environment and emphasized human use of
resources over the maintenance of ecological
processes for their own sake, but were less focused on
the economic aspect of human use than were the wise
use advocates. The wise use perspective was
espoused by those whose view of natural resources
was entirely utilitarian and their primary objective was
for rapid salvage of burned timber. Wise use advocates
viewed the environmental community as wanting to
exclude human access to resources and restrict
management activities. Environmentalists saw the wise
use advocates as motivated by short-term economic
incentives at the expense of long-term ecological
impacts (Carroll et al. 2000). This research clearly
demonstrates that the controversies around post-fire
salvage probably have more to do with societal
differences in beliefs and values than with science.
Yale University’s Global Institute of Sustainable Forestry
The condition of the local economy will also impact
decisions regarding post-fire salvage. Revenue and
jobs created by logging operations are often important
to communities in the fire–prone inland northwest.
Many of these communities are in transition, with some
segments of the population depending on resource
extraction for their livelihoods, and others having
located there for the scenery and recreational
opportunities. Each group has different values and
expect different services from the adjacent forest land;
these value systems frequently clash over management
of public lands, including post-fire logging.
CONCLUSIONS
Fire has and will likely continue to play an important
role in shaping the character of inland northwest
forests. With increased settlement, management of
these forests, both before and after fire events, must
consider ecological and socio-economic factors. Fires
cause ecological changes and post-fire management
can compound those changes. Some changes will
affect ecosystem functioning and must be addressed
from that standpoint. Other decisions relate to socioeconomic values; these must also be considered, and
the changes in societal values factored into the
decision process.
There is tremendous variability in the effects of any
given fire and in the response of the ecosystem.
Continued suppression of fires has resulted in fires
burning only under the most extreme conditions.
Ecological effects of those fires will probably be greater
than for less intense fires. Timing of post-fire
management is critical given landscape vulnerability to
erosion and the economic resources at stake.
Appropriate pre-fire forest management, including
fuels treatments and development of fire management
plans, could reduce the need for post-fire salvage when
negative impacts of logging could be more severe.
Scientific data on the efficacy and effects of post-fire
logging are scarce. The issue is contentious. Both
sides have been able to use the limited science to
support their positions. There are some who strongly
believe that post-fire salvage—and often any form of
management—is never appropriate. Their position is
not likely to change and has more to do with values
23
and beliefs than with scientific evidence. For others
who are not categorically against forest management,
the issue probably has much to do with trust. When
the same groups they see as having caused current
problems advocate for post-fire salvage logging as part
of the remediation process, they are skeptical. They
want assurances that ecosystems will be protected and
would likely be receptive to better scientific evidence to
support or refute the value of post-fire logging.
At this point—given what evidence there is—post-fire
salvage, when undertaken in response to socioeconomic or ecological objectives should be done with
careful consideration of protecting ecological values.
Doing so will help restore trust. Especially important
are ensuring that vulnerable soils are protected, water
quality is maintained or improved, post-harvest
conditions favoring regeneration of native species are
created, and wildlife needs are met to the extent
possible. Monitoring to determine the extent to which
these goals are achieved should be included and
budgeted for in the planning process.
The lack of consensus regarding appropriate
management actions following fire, particularly in the
case of postfire logging, does not subjugate the need
to act. In some cases the best course of action may in
fact be to let the ecosystem recover naturally, but this
is a management decision that must be made in light
of all available options. The scientific evidence that is
available regarding an array of management
alternatives must be considered with regard to the
characteristics, long-term goals, and potential effects
on a given ecosystem.
There are no steadfast solutions to where and when
post-fire logging is appropriate. Determining the
proper uses of salvage logging as a management tool
depends on the specific conditions of the site,
including the natural and fire histories; long-term
management goals; severity of the fire and its effects;
and the social and economic constraints and
obligations managers may face. Each of the relevant
concerns associated with post-fire logging must be
carefully considered and the pros and cons weighed
before a decision can be made. In our review and
synthesis of the literature that could inform the debate
and assist managers in decision-making, we focused
on recent, peer-reviewed papers and other
24
Scientific Basis for Forest Management in the U.S. Inland West
scientifically-based publications; however, the debate
around salvage logging is informed as much by
differences in deeply-held values about natural
resources as it is by science.
References Cited
Agee, J.K. (1993) Fire Ecology of Pacific Northwest
Forests Island Press, Washington, D.C.
Akay, A.E., Sessions, J., Bettinger, P., Toupin, R., &
Eklund, A. (2006) Evaluating the Salvage Value of
Fire-Killed Timber by Helicopter - Effects of Yarding
Distance and Time Since Fire. Western Journal of
Applied Forestry, 21, 102-107.
Beschta, R.L., Frissell, C.A., Gresswell, R.E., Hauer,
F.R., Karr, J.R., Minshall, G.W., Perry, D.A., &
Rhodes, J.J. (1995) Wildfire and Salvage Logging:
Recommendations for Ecologically Sound Post-Fire
Salvage Management and Other Post-Fire
Treatments on Federal Lands in the West,
Unpublished Work. 16 pp.
Beschta, R.L., Rhodes, J.J., Kauffman, J.B., Gresswell,
R.E., Minshall, G.W., Karr, J.R., Perry, D.A., Hauer,
F.R., & Frissell, C.A. (2004) Postfire management
on Forested Public Lands of the Western United
States. Conservation Biology, 18, 957-967.
Brown, J.K., Reinhardt, E.D., & Kramer, K.A. (2003)
Coarse Woody Debris: Managing Benefits and Fire
Hazard in the Recovering Forest. Gen. Tech. Rep.
RMRS-GTR-105, USDA Forest Service, Fort Collins,
CO, 20 pp.
Camp, A. 2002. Damage to residual trees by four
mechanized harvest systems operating in smalldiameter, mixed-conifer forests on steep slopes in
northeastern Washington: A case study. Western
Journal of Applied Forestry 17 (1): 14-22
Carroll, M.S., Findley, A.J., Blatner, K.A., Mendez,
S.R., Daniels, S.E., & Walker, G.B. (2000) Social
Assessment for the Wenatchee National Forest
Wildfires of 1994: Targeted Analysis for the
Leavenworth, Entiat, and Chelan Ranger Districts.
Gen. Tech. Rep. PNW-GTR-479, USDA Forest
Service, Corvallis, OR, 114 pp
Yale University’s Global Institute of Sustainable Forestry
Donato, D.C., Fontaine, J.B., Campbell, J.L.,
Robinson, W.D., Kauffman, J.B., & Law, B.E. (2006)
Post-Wildfire Logging Hinders Regeneration and
Increases Fire Risk. Science, 311, 352.
Dwire, K.A. & Kauffman, J.B. (2003) Fire and riparian
ecosystems in landscapes of the western USA.
Forest Ecology and Management, 178, 61-74.
Hadfield, J.S. 1988. Integrated pest-management of a
western spruce budworm outbreak in the Pacific
Northwest. Northwest Environmental Journal 4 (2):
301-312
Haggard, M. & Gaines, W.L. (2001) Effects of standreplacement fire and salvage logging on a
cavity-nesting bird community in eastern Cascades,
Washington. Northwest Science, 75, 387-396.
Hanson, J.J. & Stuart, J.D. (2005) Vegetation
responses to natural and salvage logged fire edges
in Douglas-fir/hardwood forests. Forest Ecology and
Management, 214.
Ice, G. & Beschta, R.L. (1999) Should Salvage Logging
be Prohibited Following Wildfire? In Proceedings of
the 1999 NCASI West Coast Regional Meeting, Vol.
II, pp. 451-459. National Council for Air and Stream
Improvement, Inc.
Jain, T., Personal Communication (2006). Email
correspondence, 20 April 2006.
Jurgensen, M.F., Harvey, A.E., Graham, R.T.,
Dumroese, D.S., Tonn, J.R., Larsen, M.J., & Jain,
T.B. (1997) Impacts of timber harvesting on soil
organic matter, nitrogen, productivity, and health of
Inland Northwest forests. Forest Science, 43, 234251.
Kolb, P.F. Testimony, Committee on Resources, US
House of Representatives. 2006. Oversight Hearing
on Scientific Research and the Knowledge-base
concerning Forest Management Following Wildfires
and
Other
Major
Disturbances.
http://resourcescommittee.house.gov/archives/109/f
fh/022406.htm. February 24, 2006.
25
Kramme, L., A. Camp, and M. Tyrrell. 2006. Insects
and their Management in Inland Northwest Forests.
Yale Global Institute of Sustainable Forestry.
Lindenmayer, D.B., Foster, D.R., Franklin, J.F., Hunter,
M.L., Noss, R.F., Schmeigelow, F.A., & Perry, D.A.
(2004) Salvage Harvesting Policies After Natural
Disturbance. Science, 303, 1303.
McIver, J.D. & Starr, L. (2001) A Literature Review on
the Environmental Effects of Postfire Logging.
Western Journal of Applied Forestry, 16, 159-167.
McIver, J.D., Adams, P.W., Doyal, J.A., Drews, E.S.,
Hartsough, B.R., Kellogg, L.D., Niwa, C.G., Ottmar,
R.D., Peck, R., Taratoot, M., Torgersen, T., &
Youngblood, A. (2003) Environmental Effects and
Economics of Mechanized Logging for Fuel
Reduction in Northeastern Oregon Mixed-Conifer
Stands. Western Journal of Applied Forestry, 18,
238-249.
McNabb, D.H. & Swanson, F.J. (1990). Effects of Fire
on Soil Erosion. In Natural and Prescribed Fire in
Pacific Northwest Forests (eds J.D. Walstad, S.R.
Radosevich & D.V. Sandberg), pp. 315. Oregon
State University Press, Corvallis, OR.
Minshall, G.W. (2003) Responses of stream benthic
macroinvertebrates to fire. Forest Ecology and
Management, 178, 155-161.
Morton, Douglas C., Megan E. Roessing, Ann E. Camp,
and Mary L. Tyrrell. 2003. Assessing the
Environmental, Social, and Economic Impacts of
Wildfire. GISF Research Paper 001. Yale School of
Forestry & Environmental Studies, New Haven, CT.
National Research Council (2000) Environmental
Issues in Pacific Northwest Forest Management
National Academy Press, Washington, DC.
Rieman, B., Lee, D., Burns, D., Gresswell, R., Young,
M., Stowell, R., Rinne, J., & Howell, P. (2003) Status
of native fishes in the western United States and
issues for fire and fuels management. Forest
Ecology and Management, 178, 197-211.
26
Scientific Basis for Forest Management in the U.S. Inland West
Robichaud, P.R., Beyers, J.L., & Neary, D.G. (2000)
Evaluating the Effectiveness of Postfire
Rehabilitation Treatments. Gen. Tech. Rep. RMRSGTR-63, USDA Forest Service, pp. 85.
Saab, V., Brannon, R., Dudley, J., Donohoo, L.,
Vanderzanden, D., Johnson, V., & Lachowski, H.
(2002) Selection of Fire-created Snags at Two
Spatial Scales by Cavity-nesting Birds Gen. Tech.
Rep. PSW-GTR-181, USDA Forest Service, pp. 835848.
Schellhaas, R., Camp, A.E., Spurbeck, D., and
Keenum, D. 2000. Report to the Colville National
Forest on the results of the South Deep watershed
fire history research. USFS Pacific Northwest
Research Station, Wenatchee Forestry Sciences Lab
(unpublished).
Sessions, J., Bettinger, P., Buckman, R., Newton, M.,
& Hamann, J. (2004) Hastening the Return of
Complex Forests Following Fire: The Consequences
of Delay. Journal of Forestry, 102, 38-45.
Sessions, J., Buckman, R., Newton, M., & Hamann,
J. (2003). The Biscuit Fire: Management Options
for Forest Regeneration, Fire and Insect Risk
Reduction and Timber Salvage. Oregon State
University College of Forestry.
Stuart, J.D., Grifantini, M.C., & Fox, L. (1993) Early
Successional Pathways Following Wildfire and
Subsequent Silvicultural Treatment in Douglas-Fir
Hardwood Forests, NW California. Forest Science,
39, 561-572.
Yale University’s Global Institute of Sustainable Forestry
27
Insects and their Management in Inland Northwest Forests
A Review and Synthesis
Linda Kramme, Ann E. Camp and Mary L. Tyrrell
Abstract
Forests provide essential products for society; demand
for such products will likely increase, and debate over
how best to manage forests will continue. Native
insects, including those that attack and kill trees, play
essential ecological roles in inland northwestern
forests. The existing science on native bark beetles
and defoliators in forests of the inland west is
extensive, yet consensus concerning its implications
is lacking. At high population densities, these insects
can cause extensive ecological, economic and
aesthetic impacts.
Insect outbreaks in inland
northwestern forests have led to often-contentious
public debate over management strategies to prevent,
control, or mitigate the impacts of these insects on
forest ecosystems and human economies. Planning
and monitoring at multiple temporal and geographic
scales is essential for effectively managing disturbance
impacts, including those arising from native insect
outbreaks.
We review and synthesize recent scientific literature
(circa 1990-2006) to better inform this debate and
guide management strategies for preventing,
controlling, or mitigating insect outbreaks in forests of
the inland northwest. Much of the data from field
research is inconclusive or contradictory. Nevertheless,
there are some general finding that, taken in
consideration with the complexity of forest ecosystem
dynamics, could be useful to forest managers.
Key Findings
Insect outbreaks can increase forest susceptibility
to other disturbances, such as wildfire and
disease; this susceptibility is a function of outbreak
severity and extent— and it changes over time.
Forests and forested landscapes containing a
diversity of species and structural attributes are
less likely to be affected by widespread insect
outbreaks.
Forest management—including excluding fires—
over the past century has altered the composition
and/or age class distribution of many inland
western forests such that they are more
homogeneous, less vigorous, and increasingly
vulnerable to extensive insect outbreaks.
There is no “one size fits all” management strategy
for controlling insect outbreaks. Management
toward constraining one species inevitably affects
other species. These effects can be positive or
negative.
The terms “thinning” and “salvage” are frequently
used as if each term represented a single
homogeneous footprint on the land; in reality, both
thinning and salvage operations can be
implemented in very diverse ways, enhancing or
reducing desired outcomes. Thinning and salvage
operations have both positive and negative impacts
on complex ecosystems, non-target species and
ecosystem processes; with careful planning,
negative impacts can be at least partially mitigated.
28
Scientific Basis for Forest Management in the U.S. Inland West
Managing forests to maintain tree vigor can
reduce susceptibility to insect attacks.
Reducing stand density through thinning can
potentially decrease susceptibility to some insect
outbreaks; factors such as spacing, timing,
landscape pattern, climate, weather, insect
dynamics, and others can affect desired
outcomes.
Evidence that harvesting operations undertaken
once an insect outbreak has started can limit the
spread of beetles and defoliators is mixed and
inconclusive.
There is no conclusive evidence one way or the
other to suggest that salvage logging during or
following outbreaks can affect the extent of tree
mortality.
In some instances, allowing insect outbreaks to
occur and progress is a viable management
strategy; some insect outbreaks may counteract
some unintended consequences of past
management.
Trees that are already weakened by fire damage,
drought, or pathogens are more susceptible to a
secondary stressor such as an insect attack.
Introduction
Insects that feed on trees are an essential and
ubiquitous component of forest ecosystems. In inland
western North America, periodic outbreaks of bark
beetles and defoliating insects constituted an integral
part of the inherent disturbance regimes under which
the regional biota developed and persisted. Outbreaks
contributed to ecological processes and functions,
including decomposition and nutrient cycling.
Outbreaks increased the biological and structural
diversity within and among forest stands by promoting
opportunities for tree, shrub, and understory plant
regeneration, reducing stand densities, altering
species compositions, providing a food source, and
creating wildlife habitat (Black 2005, Hayes and
Daterman 2001, Mitchell and Preisler 1998, Torgersen
2001). More recently, extensive outbreaks—blamed
in part on global warming or past management
practices—are causing widespread tree mortality with
concomitant ecological and economic impacts.
The past two decades have seen extensive and often
contentious debate about whether and how to respond
to recent widespread insect outbreaks in the inland
northwest (Lindenmayer et al. 2004). Some advocate
that insect outbreaks are a natural ecological process
and should be allowed to run their course without
human intervention. Others contend that recent
outbreaks are unprecedented ecological disasters
requiring intervention such as thinning and extensive
salvage logging to contain their spread and prevent
subsequent catastrophic wildfire.
This paper reviews recent (since about 1990) research
on some of the most damaging northwestern forest
insects, and management strategies for preventing,
controlling, or mitigating their outbreaks. We
emphasize peer-reviewed research, but also report on
other published literature, including symposium
proceedings. Because most research focused on a
particular insect, host, or geographic area, we used
caution in interpreting the relevance of individual
studies over wider geographic areas and forest types.
Geographical interpretations of the “inland northwest”
vary; in this paper we restrict our definition to nonalpine forests in interior British Columbia, eastern
Washington and Oregon, and parts of Idaho, Montana,
and Wyoming—generally forests between the
Cascades and Rocky Mountins. We also include a few
studies from adjacent areas that were especially
relevant to one or more of the above-listed topics. The
table at the end of the paper lists studies included in
this review and provides additional information
including their geographical locations.
Our review and synthesis covers the following topics:
Insects of concern to inland northwest forest
managers; historic management of inland
northwestern forests; research on bark beetles;
research on defoliators; insect outbreaks and fire;
thinning to improve stand vigor and prevent insect
infestations; thinning to suppress or limit the spread of
an existing outbreak; and large-scale salvage logging
after insect outbreak.
Yale University’s Global Institute of Sustainable Forestry
Insects of Concern to Inland Northwest Forest
Managers
Two general categories of insects affect inland
northwestern forests: bark and wood boring beetles
(Order Coleoptera, Family Scolytidae) (Hayes and
Daterman 2001) and defoliators (Orders Lepidoptera
and Homoptera) (Torgersen 2001).
Bark beetles
Two species of bark beetle are currently inflicting
extensive damage in inland northwestern forests: the
mountain pine beetle (Dendroctonus ponderosae
Hopkins) (MPB), and the Douglas-fir beetle
(Dendroctonus pseudotsugae Hopkins) (DFB). The
former attacks many species of pine (Pinus), but is
currently causing extensive mortality of lodgepole ( P.
contorta) and ponderosa pines (P. ponderosa); the
latter attacks only Douglas-fir (Pseudotsuga menziesii).
Other bark and wood-boring beetles of concern to
forest managers include the western pine beetle
(Dendroctonus brevicomis LeConte) which attacks
primarily
ponderosa
pine;
spruce
beetle
(Dendroctonus rufipennis Kirby), which attacks several
species of spruce (Picea spp.); fir engraver (Scolytus
ventralis LeConte), which attacks true firs (Abies spp.);
and pine engraver (Ips pini Say), which breeds
primarily in slash and also affects severely stressed
lodgepole and ponderosa pines (Furniss and Carolin
1977). Most of these beetles are present at endemic
levels throughout the inland northwest, and all are
native to the region.
Detection of bark beetle infestations is typically
accomplished using aerial surveys followed by ground
checking (Hayes and Daterman 2001). There is
currently no pheromone-related early detection system
for beetles in the inland northwest; thus, bark beetle
infestations often impact large areas before they are
detected (Hayes and Daterman 2001). Recent
research on behavioral chemicals that disrupt mating
and host tree selection show some promise for future
management (Goyer et al. 1998).
29
Defoliators
The two major defoliators of inland northwest forests
are western spruce budworm (Choristoneura
occidentalis) (WSB) and Douglas-fir tussock moth
(Orgyia pseudotsugata) (DFTM) (Torgersen 2001).
Primary hosts of WSB are Douglas-fir and grand fir
(Abies grandis); other hosts include other true firs
(Abies spp.), and, to a smaller extent, spruce (Picea
spp.), and western larch (Larix occidentalis) (Mason
et al. 1992). The hosts of DFTM include Douglas-fir,
grand fir, white fir (A. concolor), and subalpine fir (A.
lasciocarpa) (Torgersen 2001). Both insects are native;
damage to trees by eating or mining foliage sometimes
results in heavy mortality over millions of hectares
(Torgersen 2001). Other defoliators of concern include
pandora moth (Coloradia pandora) on ponderosa and
other western pines (Speer et al. 2001, Ross 1995),
lodgepole needle miner (Coleotechnites spp.), on
lodgepole and ponderosa pines (Mason and Paul
1999), pine needle-sheath miner (Zellaria haimbachi)
on ponderosa, Jeffrey (P. jeffreyii) and lodgepole pine,
and larch casebearer (Coleophora laricella), on western
larch. Of these, only the larch casebearer is non-native,
and it has become less of a concern as recent
outbreaks have been controlled by an introduced
parasitic wasp (Hayes and Ragenovich (2001).
Unlike bark beetles that bore through the bark and
consume the phloem, thereby killing their hosts,
defoliators consume a tree’s foliage or reproductive
structures. Most trees carry enough surplus of foliage
to offset minor herbivory, but if defoliation exceeds 3050%, tree growth is measurably reduced. Most
conifers cannot withstand repeated defoliation over
several successive years. Dominant, vigorous trees are
usually more resilient to defoliation than younger,
suppressed trees (Torgersen 2001).
Shepherd (1994) differentiates western defoliators by
their outbreak dynamics. “Fast cycling” outbreaks are
caused by defoliators that outbreak suddenly and in
large numbers; intensive damage can occur within a
single year; populations usually drop precipitously
within one to four years. DFTM outbreaks follow this
pattern. “Sustained” outbreaks are caused by
defoliators that have no predictable outbreak pattern.
These insects are typically generalist, opportunistic
30
Scientific Basis for Forest Management in the U.S. Inland West
defoliators; outbreaks can take several years to
become severe. Damage from these defoliators is
more a function of duration than intensity of
defoliation. WSB outbreaks usually conform to this
pattern (Shepherd 1994).
Research and Management
Northwest Insects
of
Inland
Efforts to control insect pests in the inland northwest
have been ongoing for decades. Strategies range from
direct control (use of pesticides or removal of
individual infested trees), use of anti-aggregation
hormones, and silvicultural treatments (thinning,
fertilizing) that improve stand vigor (Hayes and
Daterman 2001). Mass trapping using pheromones
and anti-aggregation pheromone lures are largely
untested, but could potentially become useful in
controlling bark beetles and defoliators (Daterman et
al. 2004, Goyer et al. 1998).
Results of silvicultural and chemical management
strategies are mixed (Daterman et al. 2004, Goyer et
al. 1998, Torgersen 2001). Tree mortality is a function
of both beetle abundance and tree vigor; it is therefore
difficult for researchers to determine if reductions in
tree mortality following treatments result from fewer
beetles or increased tree vigor (Amman et al. 1988,
Hindmarch and Reid (2001), Preisler and Mitchell
1993).
Much of the recent literature concerning insect
impacts on western forests shows that scientists are
increasingly aware of the need for acknowledging a
wider range of complex ecological, climatic, and
human variables. Research over the past decade has
focused on quantifying stand susceptibility to insect
attack, elucidating interactions among insects and
other disturbance agents, assessing the effects of
insect predators and abiotic constraints on insect
populations, and developing hazard rating and
decision-support tools that assist land managers in
better managing insect outbreaks (DellaSala et al.
1995, Dwyer et al. 2004, Dymond et al. 2006, Hayes
and Daterman 2001, Ravlin 1991, Reynolds and
Hessburg 2005, Torgersen 2001). The importance of
temporal and spatial scales is also acknowledged in
many recent studies (Barbour et al. (2005).
Historic Forest Management in the Inland
Northwest
Many forests in the inland northwest are fire-adapted,
with most native wildlife species adapted to some level
and type of disturbance (Hemstrom 2001, Hessburg
and Agee 2003, Hessburg et al. 2000). Insect-caused
tree mortality historically played an important role in
the ecology of inland northwestern forests, helping
perpetuate some forest types like lodgepole pine, and
creating habitat for many different wildlife species (Li
et al. 2005, Logan and Powell 2001).
A century of forest management, including removing
fire as a disturbance agent, has altered the character
of many inland northwestern forests. Fire suppression
and selective harvesting of the largest pines and larch
shifted forest composition toward later seral stages.
The result in many areas was extensive, dense forests
dominated by shade-tolerant, but fire-intolerant true firs
rather than the open stands of pines that historically
dominated the landscape. The amount of Douglas-fir
has also increased. These forests are susceptible to
extensive insect outbreaks and other disturbances such
as fire, pathogens and exotic invasive species (Amman
and Logan 1998, Filip 1994, Hayes and Ragenovich
2001, Hemstrom 2001, Hessburg and Agee 2003,
Hessburg et al. 2000, Mitchell 1990, Mitchell and
Preisler 1991, Reynolds and Hessburg 2005,
Schowalter and Withgott 2001, Scott 1996, Torgersen
2001). It has been suggested that natural forests are
more resistant to major insect outbreaks than managed
forests (Scott 1996). Studies indicate that woodpeckers
and other predators are important in controlling bark
beetles and defoliators. Forests with higher populations
of predators have been shown to limit infestations of
insect pests (Hayes and Daterman 2001, Scott 1996).
Predator populations are usually higher in unmanaged
stands (Fayt et al. 2005, Schowalter and Withgott 2001,
Steeger and Hitchcock 1998).
Yale University’s Global Institute of Sustainable Forestry
Research on Bark Beetles
Mountain Pine Beetle
The mountain pine beetle (Dendroctonus ponderosae
Hopkins) (MPB) is the most destructive insect of
mature pine forests in the inland northwest. Outbreaks
in lodgepole pine stands are generally more extensive
than in ponderosa pine forests (Amman and Logan
1998). Outbreaks typically occur in large-diameter
lodgepole and ponderosa pine stands, attacking the
largest trees, however, in ponderosa pine, even small
trees are killed (Amman and Logan 1998, Anhold et
al. 1996). What is not noted in these studies is the role
of stand dynamicS and how they naturally differ
between lodgepole pine and ponderosa pine, which
will affect beetle reproduction. Current MPB outbreaks
in Canada cover vast areas; however, some argue
these extensive outbreaks are not unprecedented and
fall within historic ranges (Hughes and Drever 2001).
Before the 1970’s, control of MPB was primarily direct:
through spraying insecticides or felling and burning
infested trees (Amman et al. 1988). This strategy proved
largely ineffective over larger areas and longer
timeframes. Under endemic situations, MPB colonizes
weakened trees, but during an outbreak, any tree of
suitable size is vulnerable to attack (Amman and Logan
1998). Females find suitable (focus) trees, emit
pheromones to attract males, and lay eggs in the focus
trees; larvae spend most of their lives feeding in the
phloem tissue, and emerge as adult beetles to infect
nearby trees (Logan and Powell 2001). Trees usually die
within one year of infestation (Amman and Logan 1998).
Large infestations of MPB typically arise from small,
spot infestations that expand and coalesce (Borden
1993). Some scientists argue that once MPB
populations become epidemic, humans can do little to
limit their spread (Black 2005, Hughes and Drever
2001); however, other research indicates that for
certain forests and outbreak situations, thinning can
alleviate the damage (Amman et al. 1988, Natural
Resources Canada 2004). Outbreaks can last from 810 years; extended cold temperatures (below -40
degrees C) are the most effective killer of beetles
(Natural Resources Canada 2004).
31
Susceptibility to MPB: Studies from lodgepole pine stands
Tree Size and Age Research by Anhold et al. (1996),
Elkin and Reid (2004), Mitchell and Preisler (1991),
and others indicates that MPB preferentially attacks
large diameter (typically >10” dbh) trees.
Density Dense stands are more susceptible to MPB.
In less dense stands the microclimate is less favorable
for beetles and the trees are more vigorous. Some
authors suggest that stand structure favoring beetles is
between 750 and 1500 stems per hectare and a mean
diameter of 7.5 cm (Natural Resources Canada 2004).
Johnstone (2002) revisited long term silvicultural trials
and concluded that trees in the most heavily thinned
(less dense) stands were better able to survive MPB
attacks and that stands with greater tree species
diversity were at less risk of attack. Chojnacky et al.
(2000) concluded that, once beetles are present,
stands with a greater stand density index (SDI) can be
expected to incur more successful attacks.
Site characteristics and fire history Drier, south-facing
slopes at lower elevations increases susceptibility to
MPB (Amman and Logan 1998. Li et al. (2005). Elkin
and Reid (2004) found that high-intensity fires can kill
adult and larval MPB (but high intensity fires are also
lethal to lodgepole pine). They note MPBs did not
preferentially attack damaged trees surviving at the
periphery of fires. Li et al. (2005) argue that a more
precise assessment of age susceptibility to MPB attack
is needed to evaluate the usefulness of fire in limiting
outbreaks.
Microclimate Changes in site microclimate following
thinning appears to be an important factor in reducing
mortality from MPB. These changes, however, will
accrue differently depending on the location of the
treated stand. Bartos and Booth (1994) found higher
bark and phloem temperatures in thinned lodgepole
pine stands in Utah and suggest cooler surface
temperatures of trees in unthinned stands may provide
a more attractive environment for MPB. Amman and
Logan (1998) reviewed many earlier studies and
suggest that increased temperature following thinning
reduces habitat suitability, especially on the south side
of trees. Hindmarch and Reid (2001) found increased
populations of secondary bark beetles (i.e., ambrosia
beetles, pine engravers) along with higher temperature
32
Scientific Basis for Forest Management in the U.S. Inland West
and wind speeds in thinned stands. This study
underscores the need for further research on
management effects on non-target species, and
competitive interactions among target species (eg.
MPB) and non-target species; it also raises the
intriguing question of whether management altered
competitive dynamics among a suite of different bark
beetle species and to what effect on MPB outbreaks.
Along with Safranyik et al. (2004) results from this
study highlight the need for avoiding injury to residual
trees when managing for MPB; trees injured during
harvesting operations are vulnerable to attack by
secondary bark beetles.
Susceptibility to MPB: Studies from ponderosa pine stands
Tree Size and Age Most researchers agree that while
MPB apparently targets larger lodgepole pine, it is the
smaller ponderosa pines that are more likely to be
attacked by MPB. Otbreaks in ponderosa pine stands
also tend to be more patchy than those in lodgepole
pine (Mitchell and Preisler 1991, Amman and Logan
1998). Olsen et al. (1996) suggest MPB selection
behavior with respect to tree diameter for ponderosa
pine might not be as different from lodgepole pine as
generally believed. In their investigation of MPB
impacts in an even-aged stand comprised primarily of
susceptible ponderosa pines (>7 inches dbh), they
found density (trees per acre) and minimum dbh best
predicted MBP infestations. Chojnacky et al. (2000)
evaluated MPB risk rating systems for the Columbia
Plateau that are based on basal area, ponderosa pine
dbh, stand structure, and number of currently infested
trees; while validating the usefulness of some systems,
they emphasized that models should consider factors
other than stand characteristics. Beetles may seek out
dense pockets within stands, but factors other than
stand density likely contribute to initially bringing
beetles to a particular stand.
Density and composition Cochran and Barrett (1995)
reported high mortality of ponderosa pine where SDI
exceeded 140. Increased species diversity within
stands tends to lower vulnerability to MPB attack.
Working in Colorado, Negron and Popp (2004) found
heavily infested plots had higher basal areas and SDIs,
and more canopy ponderosa pines per hectare. Olsen
et al. (1996) found significant differences in trees per
acre, basal area, quadratic mean diameter, minimum
diameter, and range of diameters in infested versus
uninfested stands.
Microclimate In the 1980s researchers noted that
some thinning studies resulted in immediate
reductions in tree mortality from MPB, despite the fact
that measurable effects of thinning on tree vigor can
take several years (Amman et al. 1998). This led to
researchers examining how changes in temperature,
light intensity, and wind speed following thinning
impact MPB populations and behavior. Schmid et al.
(1995) studied air and bark temperatures, horizontal
wind speed, and solar radiation in thinned and
unthinned ponderosa pine stands in South Dakota,
finding that temperature changes were a function of
thinning intensity and overall temperatures were
inversely related to basal area. They further noted that
susceptible stands registered higher bark
temperatures on the south sides of trees. This is the
opposite of what Amman & Logan found (see above).
It’s difficult to tell from the papers, but this could be
because the Schmid et al. study was done in high
elevation forests of the Black Hills, and the other in
hotter, drier forests—so what is “good” in one location
is “bad” in the other when looked at from the bark
beetle perspective.
Results of studies from thinning and other management
activities in lodgepole pine
Amman et al. (1988) found thinning high elevation
lodgepole pine stands in Wyoming reduced losses to
MPB in trees greater than 5 in. dbh. Increased radial
growth in thinned stands indicated improved vigor.
Whitehead & Russo (2005) concluded that the effect
of treatment (thinning) on stands’ ability to resist attack
was less important than the reduction in frequency of
attacks, highlighting that stands can be protected
against expansion of resident populations, but not
against immigration from an existing outbreak.
Safranyik et al. (2001) confirmed earlier studies that
prescribed fires need to be very hot to control MPB
infestations in lodgepole pine stands. This study
refutes the supposition that fire damaged lodgepole
pine are very susceptible to MPB attack, but
acknowledges that fire damaged ponderosa pine may
be vulnerable.
Yale University’s Global Institute of Sustainable Forestry
Elkin and Reid (2004) studied attack and reproductive
success of MPB in fire-damaged lodgepole pine
stands, and found that beetle reproductive success
was not affected by fire damage to the trees, further
supporting the conclusions of Safranyik et al. (2001).
They note that while MPB did not preferentially attack
fire damaged trees, these trees were more likely to
succumb to attack than healthy trees at low densities
of MPB. At high beetle densities, all trees were
successfully attacked.
Borden (1993) tracked MPB spot infestations and
concluded that as their populations expand, they
unpredictably create new spots even when suitable
trees exist for colonization within the original spot.
Results of studies from thinning and other management
activities in ponderosa pine
Cochran and Barrett (1995, 1999) evaluated different
thinning regimes, concluding that stands thinned to
an SDI < 140 were less affected by subsequent MPB
attacks. Their work confirms earlier studies suggesting
competition from small trees reduces growth and vigor
of larger trees in even-aged stands, and increases
susceptibility to MPB.
Schmid and Mata (1992) studied tree mortality in MPB
infested stands, thinned to basal areas of 60, 80 and
100 sq. ft. per acre. They found no post-treatment
mortality in treated plots, but mortality continued to
occur in the control. They recommend a threshold
basal area of about 120 ft. and note that stands stocked
below 100 ft2 seem less susceptible to MPB attack.
Oester et al. (2005) examined thinning treatments in
Oregon ponderosa pine stands. Analyzing 8-inch DBH
trees in the 85-100 year old age range, they found
thinning to 80 ft2 basal area in previously unmanaged,
85-year old ponderosa pine stands increases tree
growth and lowers risk from MPB, with no appreciable
reduction in overall stand growth. They suggest that
uneven-aged management in ponderosa pine stands
might increase susceptibility to MPB.
Mitchell (1990) concluded that increases in insect
susceptibility following prescribed burns are minor and
short-term if crown scorch is avoided.
33
McHugh et al (2003) reported that following
prescribed burns and wildfire, trees with the greatest
crown damage were mostly likely to be attacked by Ips
and Dendroctonus species.
Zausen et al. (2005) found that, contrary to
expectations, trees in thinned stands exhibited
decreased resin flow, despite a decrease in water
stress. They suggest that the effects of thinning on
resin flow – one defense trees have against bark beetle
attack – cannot be generalized; trees may allocate
more carbon to growth under optimal conditions and
more to defense under somewhat stressful conditions.
Management recommendations: MPB
Although most of the research we reviewed was
relatively site-specific, some repeated findings suggest
a few generalized conclusions for managing lodgepole
and ponderosa pine forests to maintain vigor and
reduce susceptibility to MPB are warranted. These
include the following:
Early detection and immediate control of spot MPB
infestations is essential for preventing their spread
(Borden 1993).
Thinning stands and managing at lower densities can
increase tree vigor and thus reduce MPB attack
success (Cochran and Barrett 1995, Oester et al.
2005); however, other factors may confound results
(Black 2005).
Carefully planned and applied prescribed fires do not
appreciably increase the likelihood of MPB infestation,
and may actually reduce it. Avoiding crown scorch is
key to using prescribed fire for MPB management.
Ponderosa pine stands managed for a mixture of
species and age classes will be less susceptible to
MPB. This is likely because older PP that is not overly
stressed, mostly by being in uneven-aged stands with
lots of smaller, more vigorous trees, can pitch out bark
beetles. So it’s not maturity but vigor, and vigor on
these dry sites is generally a function of stand density.
Small landowners should remove individual infested
brood trees and destroy all portions containing live
beetles. Pheromone baiting or pesticides (such as
34
Scientific Basis for Forest Management in the U.S. Inland West
MSMA) should be used judiciously, with consideration
given to the time, costs and risks to workers and nontarget species (Goyer et al. 1998).
mortality is a normal part of the development of these
forests, and that it can take 25 to 200 years to return
to pre-infestation tree densities.
In their review and synthesis paper, Amman and Logan
(1998) discuss the large body of evidence supporting
the assertion that thinning deters infestations of MPB,
but go on to say that the underlying mechanisms are
largely unknown and must be determined. Sixty years
of attempted control of MPB through silviculture has
not prevented current outbreaks; it is no longer
sufficient to measure the impact of treatments on
stand susceptibility over short timeframes. What is
needed are 1) ways to predict landscape level impacts
of forest management over long timeframes and 2) the
ecological understanding necessary for incorporating
natural disturbances within sustainable forest
management objectives.
Dodds et al. (2004) used geographic information
systems (GIS) and historic DFB infestation data to test
a hazard rating system currently in use by the U.S.
Forest Service. Their data demonstrated that most
affected stands, and the greatest tree mortality, occur
in designated moderate- and high-hazard stands,
confirming the robustness of this rating system.
Douglas-Fir Beetle
No management Several authors discuss management
recommendations related to DFB. McMillin and Allen
(2000) contend that with no management toward
controlling outbreaks, 40 - 70 % of the Douglas-fir
basal area could be lost in heavily infested stands.
They posit increases of tree regeneration and forage
production after such mortality, and suggest
regeneration is likely to consist of Douglas-fir with
smaller amounts spruce, fir, and pine. They suggest
no management is a valid strategy for managers who
accept present and possible future tree mortality as a
natural process; eventually DFB populations will
collapse as a result of increased vigor in residual trees,
presence of natural enemies, loss of suitable host trees
and weather factors.
The Douglas-Fir beetle (Dendroctonus pseudotsugae
Hopkins) (DFB) attacks only Douglas-fir trees, and is
the most significant insect pest on Douglas-fir
throughout its North American range (McMillen and
Allen 2000, Negron 1998). Typically, the beetle
attacks trees that have been downed by wind or killed
by fire; once established, they can attack and kill
nearby healthy trees (McMillen and Allen 2000).
Thinning and other DFB management studies
Research on DFB infestations has focused on
characteristics of stands that make them more
susceptible to infestation, and development of models
that estimate potential losses in terms of basal area
killed (Negron 1998). Research to date indicates that
susceptible stands contain a high percentage of basal
area in Douglas fir, have high tree densities and poor
growth rates in the 5 years prior to attack (Negron
1998)1.
McMillin and Allen (2000) reported that DFB
infestations in Wyoming resulted in a 40-70%
reduction in Douglas-fir basal area; however, Douglasfir was regenerating successfully and other understory
species increased markedly. They emphasized that
DFB impacts are temporary, that periodic DFB-caused
Ross and Daterman (1995) tested the anti-aggregation
pheromone MCH on Douglas-fir stands at high risk for
infestation, and found significantly lower DFB numbers
compared to untreated stands.
Management recommendations: DFB
Salvage/sanitation harvesting Hayes and Daterman
(2001) and McMillen and Allen (2000) agree that
removing infested trees can be effective for controlling
small localized DFB populations and recommend such
sanitation harvesting be completed before the beetles
start to emerge in May of each year. Most researchers
emphasize that as populations build beyond a few
trees, salvage logging is not effective at reducing DFB
populations, although it does capture some of the
economic loss associated with DFB outbreaks.
Anti-aggregation pheromones Several authors suggest
using pheromones to disrupt aggregation and mating
behavior of beetles (McMillin and Allen 2000, Ross
and Daterman 1995).
Yale University’s Global Institute of Sustainable Forestry
Thinning McMillen and Allen (2000) report that
silvicultural treatments can reduce susceptibility in
vulnerable stands not yet infested by DFB. These
treatments include: reducing stand basal area to <
80% of normal stocking; harvesting old, mature
stands; and thinning younger stands. Douglas-fir
beetles initially attack downed trees; therefore it is
important to salvage wind- or fire-damaged trees
promptly to prevent population build-ups (Hayes and
Daterman 2001). They conclude integrating salvage
with prescribed fire and thinning is beneficial, as is
removing slash from harvesting operations.
Research on Defoliators
Western Spruce Budworm
Western spruce budworm (Choristoneura occidentalis
Freeman) (WSB) is the most destructive and widely
distributed defoliator of western mixed coniferous
forests (Mason et al. 1992). Research has shown that
the spatial and temporal extent of WSB outbreaks has
increased dramatically in the past 100 years as a result
of fire suppression, selective harvesting of non-host
species including large, old ponderosa pine, and
increased complexity of forest structure, including
presence of host species in canopy and understory
positions (Swetnam et al. 1995). Defoliation by WSB
can kill shoots, reduce stem growth, and ultimately
result in tree mortality (Waring et al. 1992). Many
forest managers recognize the value of restoring
susceptible stands to pine-dominated forests, but this
goal will take much effort and time given current forest
conditions (Waring et al. 1992).
As early as the 1940’s, forest managers in the inland
northwest were applying aerial pesticides in an attempt
to limit the spread of this WSB (Waring et al. 1992).
This strategy was expensive, effective only in the short
term, and damaging to some non-target species
(Waring et al. 1992). In the 1980s, the aggregation
pheromone of the female WSB was synthesized and
has been used since then to detect impending
outbreaks (Torgersen 2001). More recently, control
of WSB has relied on a biological control agent Bacillus thuringiensis (Bt), believed to have fewer
effects on non-target insects. However, recent studies
35
suggest Bt’s impacts on non-target species, especially
butterflies and moths, is not benign (Torgersen 2001).
Thinning and other WSB management studies
Recent research has focused on silvicultural
techniques that decrease stand vulnerability and
reduce severity of WSB outbreaks. A replicated splitplot study evaluated the effects of thinning and
nitrogen fertilization over a five-year period in an
Oregon grand fir (A. grandis) stand infested with WSB
(Mason et al. 1992, Wickman et al. 1992, Filip et al.
1992, Waring et al. 1992). The study tested the theory
that such treatments would increase foliage resistance
to WSB defoliation.
Part 1 (Mason et al. 1992), evaluating insect response,
concluded that WSB actually benefited from thinning
and fertilization. Insect biomass increased and feeding
was not deterred on treated plots. They concluded that
natural predators have a strong impact on budworm
survival.
Part 2 (Wickman et al. 1992) evaluated tree growth
response in the same stands and found that thinning
and fertilization did significantly improve tree growth.
Despite the higher biomass of WSB in the fertilized
trees, they were defoliated to a lesser degree than were
unfertilized trees. There was no significant difference
in defoliation between thinned and unthinned stands.
Part 3 (Filip et al. 1992) evaluated the effects of these
treatments on stem-wound closure and wood decay,
and concluded that such treatments could improve vigor
and reduce losses from wound-associated stem decay.
Part 4 (Waring et al. 1992) considered these treatments
from an ecosystem management perspective. They
concluded that although WSB biomass had increased
in thinned and fertilized stands, this may have been
offset by the significant increase in fir growth efficiency.
They suggested that thinning alone may encourage
more grand fir, thus providing more food for beetles.
They suggest that fertilizing with nitrogen at the onset of
a WSB outbreak might be a good strategy for reducing
the tree mortality and subsequent fire hazard associated
with these outbreaks.
36
Scientific Basis for Forest Management in the U.S. Inland West
Management recommendations: WSB
Current management recommendation for controlling
WSB is prevention: identifying potential outbreaks
through use of early detection systems, and
silviculturally restoring stands to more closely mimic
historical species compositions and structures
(Shepherd 1994). More specifically, prevention
includes reducing amounts of Douglas-fir and true firs
and reintroducing light ground fires (Waring et al.
1992, Wickman et al. 1992). Over the short term,
managers of income-producing forests need to protect
currently vulnerable forests from widespread mortality
so they can be harvested. Promoting mixed species
stands may not be feasible for industrial owners whose
goal is typically productive, even-aged single species
stands. Nitrogen fertilization may be effective in
minimizing damage from WSB in some, providing a
viable alternative to insecticide or Bt use (Wickman et
al. 1992).
Douglas-Fir Tussock Moth
The Douglas-fir tussock moth (Orgyia pseudotsugata)
(DFTM) is another major defoliator in mixed conifer
stands of the inland northwest (Mason and Wickman
1991). Defoliation severity is greatest in the hottest
and driest parts of the range of Douglas-fir (Shepherd
1994). Outbreaks typically occur at 7-14 year
intervals, and last for 3-4 years (Shepherd 1994,
Torgersen 2001). Research indicates that for similar
reasons that WSB outbreaks have increased in area
and duration, outbreaks of DFTM have also increased
both spatially and temporally over the past century
(Swetnam et al. 1995). Torgersen (2001), Mason and
Wickman (1991) and Scott (2000) note that DFTM
susceptibility increases in stands with multiple canopy
strata, older hosts (Douglas-fir and true fir), and on dry,
upper slopes on shallow soils
Impending outbreaks of DFTM can be detected using
the aggregation pheromone of the female DFTM,
which was synthesized in the 1980s (Daterman et al.
2004). As with WSB, the historic control strategy for
DFTM was use of chemical insecticides. Research on
the population dynamics of DFTM showed that
populations crashed naturally from attacks on DFTM
larvae by a nucleopolyhedrosis virus (NPV) combined
with starvation from host reduction through mortality
(Mason and Wickman 1991, Shepherd 1994). More
recently, biological control agents including the abovementioned virus and Bt are commonly used to control
DFTM outbreaks (Torgersen 2001).
Research on DFTM has waned in recent years, with
more emphasis concentrated on emerging issues
associated with large outbreaks of WSB and MPB.
However, some recent research includes information
helpful to land managers (Scott 2000).
Thinning and other DFTM management studies
Torgersen (2001) reports that many earlier studies
show increased growth of residual trees 5-10 years
following a DFTM outbreaks. In some cases this
increment exceeds growth occurring prior to the
outbreak; this is hardly surprising given that mortality
from DFTM can be high, greatly reducing competition
on resistant or non-host trees.
Management recommendations: DFTM
Prevention is very important for avoiding outbreaks
and reducing mortality from DFTM defoliation. The
spread of dense, multi-canopy forests across inland
northwestern landscapes increases the potential for
outbreaks; restoring forest composition and structure
to favor non-host species is an important long-term
strategy (Shepherd 1994).
In prioritizing stands that should be treated to reduce
susceptibility to DFTM, the most vulnerable stands
need to be targeted—those with large component of
Douglas-fir or other host species and occurring on hot,
dry sites (Shepherd 1994).
Promote ponderosa pine or other non-host species on
high-risk sites (Mason and Wickman 1991).
Vulnerable stands can be monitored for DFTM
presence and, if found, treated with the NPV virus or
Bt, which can stop DFTM populations from achieving
outbreak levels. These biological control agents are
only effective if applied before a major outbreak occurs
(Shepherd 1994).
DFTM outbreaks are of the fast cycling variety; once an
outbreak occurs, letting it run its course may prove the
most viable option.
Yale University’s Global Institute of Sustainable Forestry
Insect Outbreaks and Fire
There are two schools of thought in the literature on the
subject of wildfires and insect outbreaks. One viewpoint
contends outbreaks create conditions likely to result in
catastrophic wildfires and the other is equally adamant
that there is no evidence to support this. The dynamics
between insect outbreaks and fire are widely debated
but there is little actual research. For the research that
does exist, results vary by forest type and outbreak
severity, providing supporting evidence for either
viewpoint. Turner et al. (1999) reported the 1988 fires
in Yellowstone National Park burned more intensely
where tree mortality from previous MPB outbreaks was
high; where mortality from these outbreaks was
moderate or low, fire severity was generally less than in
stands that did not experience MPB activity prior to
burning, possibly because low to moderate amounts of
mortality tend to decrease fuel continuity within the
stand. Eng (2004) notes that evidence for increased risk
of fire in mountain pine beetle-affected stands is mixed,
and suggests that “conducting salvage operations
based on the premise of reducing fire risk is not
recommended, except in the wildland-urban interface.”
In the debate on the impact of insect outbreaks and
stand vulnerability to fire, the temporal aspect is often
ignored or taken out of context. Forests may be at high
risk for fire only in the first few years following an
outbreak (Black 2005). The temporal aspect is
important, because the fine fuels necessary to carry
fire fall to the ground and decompose over time; this is
the case for fine fuels created by insects or those left
as slash following a salvage operation. As more fires
burn over areas with varying amounts of outbreakcaused tree mortality and, perhaps more importantly,
at different post-outbreak intervals, perhaps these
questions will be answered in coming years.
Thinning to Reduce Risk of Insect Outbread &
Improve Vigor
Most scientists agree that thinning in human-altered
forests where outbreaks have not yet occurred, can
increase residual tree vigor, decrease host continuity,
and reduce tree and stand susceptibility to insect
infestation. Most thinning studies to prevent bark
37
beetle attacks in uninfested stands show a positive
correlation between low vigor and the likelihood of a
successful beetle attack. The variation observed in
many of these studies suggests factors other than tree
vigor are also influencing outbreak dynamics.
Thinning operations, like the insect outbreaks they are
meant to prevent, constitute a disturbance that can
have effects on other forest resources. In a special
issue of Northwest Science, scientists reviewed the
literature and discussed insect outbreaks and their
management from the standpoint of ancillary forest
resources. Bull and Wales (2001a) concluded that
most amphibians are not likely to be negatively
affected by tree mortality associated with insect
outbreaks or by thinning to increase forest health;
however, several species of conservation interest
including the tailed frog, Larch Mountain salamander,
and Cope’s giant salamander could be adversely
impacted because of their requirements for shade and
moisture levels associated with an intact overstory.
Bull and Wales (2001b), Steeger and Hitchcock
(1998) and Saab and Dudley (1998) discuss effects
of disturbances (such as insect outbreaks, fire, and
thinning intended to promote forest health), on birds
and of conservation in the inland northwest. Insect
outbreaks have positive and negative effects on these
birds. They create dead trees, cavities and downed
logs that provide habitat and food for woodpeckers—
thought to be the most important natural predators on
bark beetles (Fayt et al. 2005)—and other cavitynesting birds such as nuthatches (Torgersen and Bull
1995, Steeger and Hitchcock 1998). Both insects and
thinning can destroy nest trees used by bald eagles,
goshawks, ferruginous hawks, and harlequin ducks
(Anthony and Isaacs 1989). Thinning and insect
mortality create more open canopied forests beneficial
to the black rosy finch, and more prey habitat for
raptors.
Steeger and Hitchcock (1998) caution against
removing snags during thinning operations; this can
reduce the nesting success of some “weak cavity
nesters” such as the red-breasted nuthatch. While
acknowledging that both insect outbreaks and thinning
operations to prevent them benefit some species and
may harm others, Bull and Wales (2001b) recommend
removal of roads following thinning as being very
38
Scientific Basis for Forest Management in the U.S. Inland West
beneficial for most bird species of conservation
concern in eastern Oregon and eastern Washington.
With respect to forest carnivores Bull et al. (2001) note
that Canada lynx, wolverine, and fisher all depend to
some extent on the forest structures, stands, downed
logs, and landscapes created by insects.
Howell (2001) describes the impacts of certain types of
thinning on fish and fish habitat, and Wondzell (2001)
addresses impacts on erosion and stream
sedimentation. Both scientists emphasize that road
construction and thinning operations can alter water
flows, affect quantity of woody debris in streams,
change water temperature and clarity, destroy fish
habitat, flush fish eggs and fry downstream, and reduce
stream productivity. They recommend using lowerimpact logging systems and “pulsed” treatments that
mimic natural disturbance patterns. Howell (2001)
ascertains that the greatest impact is on fish that swim
great distances and depend on side channels during
one or more life stages. Wondzell (2001) cautions that
most studies on effects of thinning on streams are
conducted at scales that are too small to assess their
cumulative, larger-scale impacts.
As reported earlier, Hindmarch and Reid (2001) found
increased populations of secondary bark beetles (i.e.,
ambrosia beetles, pine engravers) along with higher
temperature and wind speeds in thinned stands. This
suggests that thinning could have unanticipated effects
on many types of insects, both damaging and beneficial.
Camp (2002) evaluated damage to residual trees in an
overstocked stand thinned using different mechanized
harvesting systems. Cut-to-length (CTL) processing
resulted in less damage to residual trees than wholetree harvest, and skyline yarding caused less damage
than forwarder yarding. Damage to residual trees can
cause infection courts for decay fungi and trade one
forest health problem for another.
Hartsough et al. (2001) describe logging cost models
that assist managers with long-term planning that
incorporates thinning small trees in natural stands.
They contend that using these models will allow
managers to realize a return on investment for thinning
stands to promote vigor.
Thinning to Reduce Impacts from Existing
Insect Outbreaks
Numerous studies over several decades have tested
effectiveness of thinning ponderosa and lodgepole
pine stands with existing insect infestations (Amman
and Logan 1998, Schmid and Mata 1992, Oester et
al. 2005, Mason et al. 1992, Wickman et al. 1992,
Filip et al. 1992, Waring et al. 1992). Results have
been mixed and provide support for those on either
side of the debate.
Black (2005) reviewed much of this literature and
expressed strong skepticism of studies concluding that
thinning during bark beetle outbreaks contain or
suppress them. He argues that evidence supporting
this type of thinning is based on measuring posttreatment tree vigor and not on insect activity in treated
stands. He reviewed over 300 papers on bark beetles
and other perceived forest pests, finding no evidence
supporting the claim that thinning can effectively
control insects during an outbreak.” He suggests
thinning projects are redundant and unnecessary
because the insects themselves are reducing tree
densities. Furthermore, he contends that removing
infested trees prior to brood emergence is unproven
and not feasible over larger areas. He asserts that
historic patterns of MPB outbreak clearly indicate that
as long as environmental conditions are favorable,
outbreaks only cease when almost all susceptible trees
are killed or removed by logging (Black 2005). He
agrees that treating individual trees, by using
techniques such as felling, peeling and burning, could
potentially slow the spread of an insect outbreak, but
the end result is inevitable.
Muzika and Liebhold (2000) also question
justifications for thinning during outbreaks to limit the
spread of defoliators. Goyer et al. (1998) note that
attempts to control MPB through thinning could lead
to outbreaks of bark beetles in the genus Ips as these
beetles breed in slash which is often a byproduct of
thinning operations.
Yale University’s Global Institute of Sustainable Forestry
Post-Mortality Salvage Logging
Salvage logging during or following outbreaks is
another contentious issue where a preponderance of
the rhetoric is based on limited research. Many
researchers do have opinions, and some are quick to
offer them. Unfortunately, those on either side of the
debate typically fail to adequately define the scope and
methods that might be used for a particular salvage
operation. Salvage differs from conventional harvests
only in that trees targeted for removal are already dead
or expected to die within a short time. Thus, a salvage
harvest can be implemented with any existing logging
system or combinations thereof. Yet we continue to
discuss the pros and cons of “salvage logging” as if it
were one thing. Much of what has been written in
support of salvage highlights its potential for reducing
the economic loss associated with the original
disturbance. Those in opposition focus on potential
negative
ecological
consequences,
rarely
acknowledging the various methods for mitigating
such consequences.
39
processes in a system that could otherwise limit insect
outbreaks. They describe the current MPB outbreak
in British Columbia as a “socio-economic challenge
and not an ecological crisis” and contend that control
efforts have little effect on outbreak size, but in some
instances may retard outbreak progress. They
acknowledge that control of MPB outbreaks is
theoretically possible, but would require removing
almost all of the infected trees over a short duration,
with negative ecological consequences and leading to
unsustainable economies in affected regions.
Although little research exists on the effects of largescale salvage logging on specific species and
ecological processes in inland northwest forests, two
recent papers discuss how such salvage logging could
affect overall forest values and processes (Eng 2004,
Bunnell et al. 2004). These studies—especially the
one by Bunnell et al. (2004) and reported on in more
detail below—use life history requirements of inland
northwest forest species to predict effects of salvage
logging on terrestrial and aquatic vertebrates.
Effects on terrestrial vertebrates
Large-scale salvage logging has been proposed where
insects have killed trees over extensive areas, such as
in MPB damaged forests in British Columbia.
Supporters argue that harvesting following extensive
outbreaks reduces associated costs and road densities
(Natural Resources Canada 2004). Salvage logging
recovers some of the lost revenue. Others suggest that
salvage logging may slow the spread of beetles into
new areas (Bunnell et al. 2004, Hayes and Daterman
2001). Black (2005) and Eng (2004) indicate that
salvage harvests come in different flavors, with large,
“clean” clearcuts doing little to protect habitat values;
they further warn that this type of salvage operation
could result in future forests even more susceptible to
insect outbreaks.
Bunnell et al. (2004) show salvage logging actually
enhances biodiversity in some forests. Using natural
history characteristics of 182 terrestrial vertebrate
species in British Columbia, he concluded that
salvaging forests killed by MPB potentially benefits
65% of the resident, terrestrial vertebrate fauna in the
short term, and negatively affects 35%. Birds and
mammals favored are those requiring early seral
habitat such as blue grouse, lazuli bunting, warbling
vireo, brown lemming, long-tailed vole and meadow
jumping mouse. Addition of large woody debris (LWD)
during the harvesting operation would increase habitat
for a variety insects and other species.
Lindenmayer et al. (2004) emphasize that salvage
harvesting activities may undermine many of the
ecosystem benefits that accrue following major
disturbances. They note that some species may not
tolerate two major disturbances in rapid succession.
Hughes and Drever (2001) warn that salvage logging
leads to reduced habitat complexity and diversity, and,
unlike natural disturbances, can impact or destroy key
Negative effects of salvage logging typically accrue
most heavily in riparian habitats, deciduous stands,
older forests, and remaining live trees, impacting
cavity-nesting and denning species in particular
(Bunnell et al. 2004). Some species are seral
generalists—species not as sensitive to a particular
phase of forest development. For these species,
salvage logging would likely have a neutral effect.
Examples include western toad, grizzly bear, northern
flicker and peregrine falcon. These species do require
40
Scientific Basis for Forest Management in the U.S. Inland West
at least a few trees within an otherwise extensive
clearcut, as well as some edge habitat and tree
cavities, especially near or in riparian areas, and where
salvage cuts are large, retention of some uncut
patches (Bunnell et al. 2004).
variability for natural disturbances (including fire) in
these forests and may be appropriate for salvage
logging; however, unharvested blocks within these
openings should increase proportionally to promote
landscape scale structural diversity (Eng 2004).
Bunnell et al. (2004) warn that birds and mammals
described as “forest interior species” are the ones
most threatened by salvage logging. These species
show preference for large, contiguous tracts of forest
(that might or might not be provided by outbreakravaged, but unsalvaged tracts). Species falling into
this category include fisher, caribou, barred owl, brown
creeper, hermit thrush, golden-crowned kinglet, blackheaded grosbeak, Townsend’s solitaire, varied thrush,
white-breasted nuthatch and southern red-backed
vole. Removal of 40% or more of forest cover over
large areas will likely impact these “interior” species
negatively, even where riparian areas and other tree
species are not harvested. There are also terrestrial
vertebrates that utilize inland northwest forests during
only part of their lifecycle, including migratory birds
and some amphibians (Bunnell et al. 2004).
How Much Dead Wood to Leave Behind?
Effects on Freshwater Fish
Importance of Planning for Salvage Logging
As with terrestrial vertebrates, some kinds and
intensities of salvage logging could be beneficial for
specific aquatic vertebrates at some point in their
lifecycle, but negative effects of salvage logging on
aquatic species typically far outweigh any benefits
(Bunnell et al. 2004). Large-scale salvage logging can
impact fish at each of their four life stages: egg, fry,
juvenile and adult. Major consequences of large-scale
salvage logging to streams include alteration in water
flows and yields, increased sedimentation, increased
debris that could present a barrier to fish movement,
changes in primary productivity, and increased water
temperatures (Bunnell et al. 2004).
Bunnel et al. (2004), Eng (2004), Hughes and Drever
(2001), Lindenmayer et al. (2004), and others
emphasize the importance of careful planning at the
stand and landscape-level scales prior to
implementing salvage operations. These authors
make the following (some forest type specific)
recommendations for planning and executing largescale salvage operations at the STAND LEVEL:
Size of Salvage Logging Operations.
Eng (2004) notes that, prior to the current MPB
epidemic in British Columbia, forest companies would
typically clearcut blocks <60 hectares, maintaining a
mosaic of different age classes. Since the outbreaks,
salvage operations of more than 1,000 hectares are
being planned (Eng 2004). These large openings
(>1000 hectares) are within historic ranges of
Eng (2004) and Bunnell et al. (2004) recommend preoutbreak landscape management plans be followed
despite salvage logging, and that “the ‘footprint’
caused by combined green tree and salvage
harvesting should not significantly exceed that which
would have occurred in the absence of the outbreak.
Eng (2004) recommends high levels of LWD be
retained on sites even with salvage operations. He
recommends 9 m3 on dry sites, 15 m3 on mesic sites,
and 25 m3 on wet sites (Eng 2004). Stands stocked
with pole-sized regeneration of species other than pine
should be low priority for salvage, because these
stands are already diverse and can proceed through
stand development stages better than stands lacking
such an understory.
Retain species other than lodgepole pine during
logging; this can help retain terrestrial vertebrate
species as well as bryophytes, lichens and nonpest invertebrates.
Leave hardwood trees where possible; these are
essential habitat for many terrestrial vertebrates
such as woodpeckers.
Control minor vegetation sparingly, and encourage
shrub cover. Many terrestrial species, especially
birds, depend on shrub cover.
Retain small groups of remnant trees (alive and
dead); this can provide significant gains in the
number of vertebrate species retained during
Yale University’s Global Institute of Sustainable Forestry
41
salvage logging, and could help some early seral
or generalist species.
Conclusion
Leave slash >15 cm in diameter, and scatter it
randomly, rather than piling and burning. Be
mindful that the benefits of leaving slash can also
have negative consequences if secondary bark
beetles subsequently invade.
There is no “silver bullet” solution for addressing the
challenges of insect outbreaks, thinning, salvage
logging, and forest health in the inland northwest.
Thinning and salvage logging should be done in a way
that promotes the complexity, species compositions,
stand structures and ecological processes that
historically occurred in these forests to avoid
increasing susceptibility to future insect outbreaks or
other disturbances. A management strategy that
focuses on ecosystem integrity is essential. Research
in recent years suggests global climate change will
increase future uncertainty about insect dynamics in
forests (Logan and Powell, 2001).
Follow best practices guidelines when harvesting
near streams and rivers. Protecting riparian zones
during salvage logging is essential. Keep
connections open between main and side
channels.
Create tall stumps or stubs as cavity sites where
possible in larger trees.
Areas designated for protection before infestations
should be left intact.
Where possible, recruitment of species other than
pine should be encouraged to ensure diversity.
Retain unharvested riparian buffers around
wetlands and lakes, and avoid log storage within
lakes.
These authors further recommend the following
LANDSCAPE LEVEL considerations when planning
salvage harvests:
Design harvested and reserved areas as large
blocks (avoid fragmenting the landscape).
Within larger harvest blocks (up to 1000 ha),
conduct operations rapidly and deactivate new
roads wherever possible. Retain some 10-100 ha
patches, plus some smaller patches within large
salvage areas; this is essential for terrestrial
vertebrates, and for reducing impacts to aquatic
species.
Avoid salvage in areas where intermixed pine
represents <40% of the species mix
Reserve half of each known lodgepole pine
ungulate winter range from salvage
Leave-areas should include areas in which there
are high densities of fish species that are highly
sensitive to salvage logging.
As evidenced by the volume of research summarized
above, the topic of insects and thinning in the inland
northwest is broad and complex. Despite a huge
amount of research there are still many questions to be
answered, especially related to long-term monitoring
in stands where research and management has
occurred (Amman and Logan 1998). Better models
need to be developed to predict the pattern of spread,
outbreak and control.
Despite the remaining
questions, several general conclusions can be drawn:
Bark beetles and defoliators are part of the native
biota and play important roles in inland
northwestern forest ecosystems.
A century of forest management and excluding
fires has altered inland northwestern forests,
increasing host continuity across landscapes and
leading to larger and longer outbreaks of bark
beetles and defoliators.
In tandem with increased host continuity, a
warming climate may increase host tree
susceptibility and interrupt important climatic
controls on insects, increasing the extent and
duration of outbreaks.
As more people move to the inland west,
expansion of the wildland urban interface puts
more people in contact with forests. People are
concerned about the health of inland western
forests for reasons of their own safety, but also
because of their concern for wildlife, water
resources, and local economies; management
42
Scientific Basis for Forest Management in the U.S. Inland West
toward preventing, controlling, or mitigating insect
outbreaks will need to address the socio-economic
as well as the biophysical aspects of forest
management.
Long-range planning at stand and landscape
levels is critical.
Considerations about forest resources and risk of
disturbances should be integrated into decisions about
how to manage forests to increase their value to
society, keeping in mind that the value of these forests
is more than the commodities extracted from them.
Disturbances, including insect outbreaks and
management toward preventing, controlling, or
mitigating their effects, afford opportunities for the
incursion and spread of invasive, alien species.
Management focused on native insects should
consider potential impacts from non-native
species.
It is important to maintain and restore the stand
structures and species compositions of inland
northwest forests, including all phases of forest
development, from stand initiation through old
growth. Restoration of inland northwestern forests
must consider the dynamic nature of these
forests, the inherent disturbance regimes that
historically shaped them, and the landscape
context of the mosaic of different forest types.
Managers should utilize independently tested
hazard rating systems and decision-support tools
where available, recognizing their limitations
(Dymond et al. 2006).
The most effective strategy for thinning and
salvage logging should focus on both what is taken
out and what is left behind; improved tree vigor
may reduce susceptabilty to future insect attack;
retention of large trees and snags, downed wood
and patches of untreated areas provide critical
habitat for a variety of wildlife species, including
those that prey on insect pests.
Designing and implementing thinning and salvage
logging that minimizes soil compaction, disruption
of hydrological function and injury to residual trees
is essential for protecting ancillary forest values.
In some areas and for some kinds of outbreaks,
doing nothing is a viable alternative to active
management; insect outbreaks may help
counteract some of the unintended consequences
of past management, including fire suppression.
Additional roads required for thinning or salvage
operations should be designed to minimize
ecological impacts; decommissioning roads after
conclusion of operations helps restore ecosystem
function and protects wildlife.
Treatments for preventing, controlling, or
mitigating insect outbreaks should include posttreatment monitoring over short- and long
timeframes. This strategy will promote the
continuing evolution of a science-based approach
for maintaining the variety of values that inland
northwest forests provide. GIS and remote sensing
data can be especially useful in monitoring efforts
(Ravlin 1991).
1
This study was conducted in the Colorado Front
Range, so applicability to locations in the inland
northwest should be considered.
Yale University’s Global Institute of Sustainable Forestry
References Cited
Amman, G.D., Lessard, G.D., Rasmussen, L.A., &
O’Neil, C.G. 1988. Lodgepole Pine Vigor,
Regeneration, and Infestation by Mountain PineBeetle Following Partial Cutting on the Shoshone
National Forest, Wyoming. USDA Forest Service
Intermountain Research Station Research Paper, 1-8.
Amman, G.D. & Logan, J.A. 1998. Silvicultural control
of mountain pine beetle: prescriptions and the
influence of microclimate. American Entomologist,
44, 166-177.
Anhold, J.A., Jenkins, M.J., & Long, J.N. 1996.
Management of lodgepole pine stand density to
reduce susceptibility to mountain pine beetle attack.
Western Journal of Applied Forestry, 11, 50-53.
Anthony, R.G. & Isaacs, F.B. 1989. Characteristics of
Bald Eagle Nest Sites in Oregon. Journal of Wildlife
Management, 53, 148-159.
Barbour, R.J., Hemstrom, M., Ager, A., & Hayes, J.L.
2005. Effects of spatial scale on the perception and
assessment of risk of natural disturbance in forested
ecosystems: Examples from Northeastern Oregon.
Forest Ecology and Management, 211, 210-225.
Bartos, D.L. & Booth, G.D. 1994. Effects of Thinning
on Temperature Dynamics and Mountain PineBeetle Activity in a Lodgepole Pine Stand. USDA
Forest Service Intermountain Research Station
Research Paper, 479, 1-9.
Black, S.H. 2005. Logging to Control Insects: The
Science and Myths Behind Managing Forest Insect
“Pests”: A synthesis of independently reviewed
research. Xerces Society, Portland, OR.
Borden, J.H. 1993. Uncertain fate of spot infestations
of the mountain pine beetle, Dendroctonus
ponderosae Hopkins. Canadian Entomologist, 125,
167-169.
Bull, E.L., Aubry, K.B., & Wales, B.C. 2001. Effects of
disturbance on forest carnivores of conservation
concern in eastern Oregon and Washington.
Northwest Science, 75, 180-184.
43
Bull, E.L. & Wales, B.C. 2001a. Effects of disturbance
on amphibians of conservation concern in eastern
Oregon and Washington. Northwest Science, 75,
174-179.
Bull, E.L. & Wales, B.C. 2001b. Effects of disturbance
on birds of conservation concern in eastern Oregon
and Washington. Northwest Science, 75, 166-173.
Bunnell, F.L., Squires, K.A., & Houde, I. 2004.
Evaluating effects of large-scale salvage logging for
mountain pine beetle on terrestrial and aquatic
vertebrates, Rep. No. Working Paper 2004 - 2.
Mountain Pine Beetle Initiative, Canadian Forest
Service, Vancouver, B.C.
Camp, A. 2002. Damage to residual trees by four
mechanized harvest systems operating in smalldiameter, mixed-conifer forests on steep slopes in
Northeastern Washington: a case study. Western
Journal of Applied Forestry, 17, 14-22.
Chojnacky, D.C., Bentz, B.J., & Logan, J.A. 2000.
Mountain pine beetle attack in ponderosa pine:
Comparing methods for rating susceptibility. U.S.
Department of Agriculture, Forest Service, Rocky
Mountain Research Station, Ogden, UT.
Cochran, P.H. & Barrett, J.W. 1995. Growth and
Mortality of Ponderosa Pine Poles Thinned to
various Densities in the Blue Mountains of Oregon.
USDA Forest Service Pacific Northwest Research
Station Research Paper.
Cochran, P.H. & Barrett, J.W. 1999. Thirty-five-year
growth of ponderosa pine saplings in response to
thinning and understory removal. USDA Forest
Service Pacific Northwest Research Station Research
Paper.
Daterman, G.E., Wenz, J.M., & Sheehan, K.A. 2004.
Early Warning System for Douglas-fir tussock moth
outbreaks in the western United States. Western
Journal of Applied Forestry, 19, 232-241.
DellaSala, D.A., Olson, D.M., Barth, S.E., Crane, S.L.,
& Primm, S.A. 1995. Forest health: moving beyond
rhetoric to restore healthy landscapes in the inland
Northwest. Wildlife Society Bulletin, 23, 346-356.
44
Scientific Basis for Forest Management in the U.S. Inland West
Dodds, K.J., Ross, D.W., Randall, C., & Daterman, G.E.
2004. Landscape level validation of a Douglas-fir
beetle stand hazard-rating system using
geographical information systems. Western Journal
of Applied Forestry, 19, 77-81.
Dwyer, G., Dushoff, J., & Yee, S.H. 2004. The
combined effects of pathogens and predators on
insect outbreaks. Nature, 430, 341-345.
Dymond, C.C., Wulder, M.A., Shore, T.L., Nelson, T.,
Boots, B., & Riel, B.G. 2006. Evaluation of risk
assessment of mountain pine beetle infestations.
Western Journal of Applied Forestry, 21, 5-13.
Elkin, C.M. & Reid, M.L. 2004. Attack and
reproductive success of mountain pine beetles
(Coleoptera: Scolytidae) in fire-damaged lodgepole
pines. Environmental Entomology, 33, 1070-1080.
Eng, M. 2004. Forest stewardship in the context of
large-scale salvage operations: an interpretation
paper, Rep. No. Tech. Rep. 019. B.C. Min. For.,
Res. Br., Victoria, B.C.
Fayt, P., Machmer, M.M., & Steeger, C. 2005.
Regulation of spruce bark beetles by woodpeckers
- a literature review. Forest Ecology and
Management, 206, 1-14.
Filip, G.M. 1994. Forest Health Decline in Central
Oregon - a 13-Year Case-Study. Northwest Science,
68, 233-240.
Filip, G.M., Wickman, B.E., Mason, R.R., Parks, C.A.,
& Hosman, K.P. 1992. Thinning and NitrogenFertilization in a Grand Fir Stand Infested with
Western Spruce Budworm .3. Tree Wound
Dynamics. Forest Science, 38, 265-274
Furniss, R.L. and Carolin, V.M. 1977. Western forest
insects. U.S.D.A. Forest Service. Misc. Publ. 1339,
Wash. D.C., 654.
Goyer, R.A., Wagner, M.R., & Schowalter, T.D. 1998.
Current and proposed technologies for bark beetle
management. Journal of Forestry, 96, 29-33.
Hartsough, B.R., Zhang, X.S., & Fight, R.D. 2001.
Harvesting cost model for small trees in natural
stands in the Interior Northwest. Forest Products
Journal, 51, 54-61.
Hayes, J.L. & Daterman, G.E. 2001. Bark beetles
(Scolytidae) in eastern Oregon and Washington.
Northwest Science, 75, 21-30.
Hayes, J.L. & Ragenovich, I. 2001. Non-native invasive
forest insects of eastern Oregon and Washington.
Northwest Science, 75, 77-84.
Hemstrom, M.A. 2001. Vegetative patterns,
disturbances, and forest health in eastern Oregon
and Washington. Northwest Science, 75, 91-109.
Hessburg, P.F. & Agee, J.K. 2003. An environmental
narrative of Inland Northwest United States forests,
1800-2000. Forest Ecology and Management, 178,
23-59.
Hessburg, P.F., Smith, B.G., Salter, R.B., Ottmar, R.D.,
& Alvarado, E. 2000. Recent changes (1930s1990s) in spatial patterns of interior northwest
forests, USA. Forest Ecology and Management,
136, 53-83.
Hindmarch, T.D. & Reid, M.L. 2001. Thinning of
mature lodgepole pine stands increases scolytid
bark beetle abundance and diversity. Canadian
Journal of Forest Research-Revue Canadienne De
Recherche Forestiere, 31, 1502-1512.
Howell, P.J. 2001. Effects of disturbance and
management of forest health on fish and fish habitat
in eastern Oregon and Washington. Northwest
Science, 75, 157-165.
Hughes, J. & Drever, R. 2001. Salvaging Solutions:
Science-based management of BC’s pine beetle
outbreak. David Suzuki Foundation, Forest Watch
of British Columbia and Canadian Parks and
Wilderness Society (BC Chapter).
Johnstone, W.D. 2002. Thinning lodgepole pine in
Southeastern British Columbia: 46-year results.
Victoria, Canada: Ministry of Forests, British
Columbia.
Yale University’s Global Institute of Sustainable Forestry
45
Li, C., Barclay, H.J., Hawkes, B.C., & Taylor, S.W.
2005. Lodgepole pine forest age class dynamics
and susceptibility to mountain pine beetle attack.
Ecological Complexity, 2, 232-239.
Mitchell, R.G. & Preisler, H.K. 1998. Fall rate of
lodgepole pine killed by the mountain pine beetle in
central Oregon. Western Journal of Applied Forestry,
13, 23-26.
Lindenmayer, D.B., Foster, D.R., Franklin, J.F., Hunter,
M.L., Noss, R.F., Schmiegelow, F.A., & Perry, D.
2004. Ecology - Salvage harvesting policies after
natural disturbance. Science, 303, 1303-1303.
Muzika, R.M. & Liebhold, A.M. 2000. A critique of
silvicultural approaches to managing defoliating
insects in North America. Agricultural and Forest
Entomology, 2, 97-105.
Logan, J.A. & Powell, J.A. 2001. Ghost forests, global
warming, and the mountain pine beetle (Coleoptera:
Scolytidae). American Entomologist, 47, 160-172.
Natural Resources Canada, Canadian Forest Service.
2004. Mountain pine beetle management: a guide
for small woodland operations. Natural Resources
Canada, Canadian Forest Service, Pacific Forestry
Centre, Mountain Pine Beetle Initiative.
Mason, R.R. & Paul, H.G. 1999. Long-term dynamics
of lodgepole needle miner populations in central
Oregon. Forest Science, 45, 15-25.
Mason, R.R. & Wickman, B.E. 1991. Integrated PestManagement of the Douglas-Fir Tussock Moth.
Forest Ecology and Management, 39, 119-130.
Mason, R.R., Wickman, B.E., Beckwith, R.C., & Paul,
H.G. 1992. Thinning and Nitrogen-Fertilization in a
Grand Fir Stand Infested with Western Spruce
Budworm .1. Insect Response. Forest Science, 38,
235-251.
McHugh, C.W., Kolb, T.E., & Wilson, J.L. 2003. Bark
beetle attacks on ponderosa pine following fire in
northern Arizona. Environmental Entomology, 32,
510-522.
McMillin, J.D. & Allen, K.K. 2000. Impacts of Douglasfir beetle on overstory and understory conditions of
Douglas-fir stands, Shoshone National Forest,
Wyoming. USDA Forest Service, Rocky Mountain
Region, Golden, CO.
Mitchell, R.G. 1990. Effects of prescribed fire on insect
pests. In Natural and Prescribed Fire in Pacific
Northwest Forests (eds J.D. Walstad, S.R.
Radosevich & D.V. Sandberg), pp. 111-116. Oregon
State University Press, Corvallis, OR.
Mitchell, R.G. & Preisler, H.K. 1991. Analysis of Spatial
Patterns of Lodgepole Pine Attacked by Outbreak
Populations of the Mountain Pine-Beetle. Forest
Science, 37, 1390-1408.
Negron, J.F. 1998. Probability of infestation and extent
of mortality associated with the Douglas-fir beetle in
the Colorado Front Range. Forest Ecology and
Management, 107, 71-85.
Negron, J.F. & Popp, J.B. 2004. Probability of
ponderosa pine infestation by mountain pine beetle
in the Colorado Front Range. Forest Ecology and
Management, 191, 17-27.
Oester, P.T., Emmingham, W.H., & Larson, P. 2005.
Thinning alternatives for ponderosa pine: Tools and
strategies for family forest owners. Western Journal
of Applied Forestry, 20, 216-223.
Olsen, W.K., Schmid, J.M., & Mata, S.A. 1996. Stand
characteristics associated with mountain pine beetle
infestations in ponderosa pine. Forest Science, 42,
310-327.
Preisler, H.K. & Mitchell, R.G. 1993. Colonization
Patterns of the Mountain Pine-Beetle in Thinned
and Unthinned Lodgepole Pine Stands. Forest
Science, 39, 528-545.
Ravlin, F.W. 1991. Development of Monitoring and
Decision-Support Systems for Integrated PestManagement of Forest Defoliators in North-America.
Forest Ecology and Management, 39, 3-13.
46
Scientific Basis for Forest Management in the U.S. Inland West
Reynolds, K.M. & Hessburg, P.F. 2005. Decision
support for integrated landscape evaluation and
restoration planning. Forest Ecology and
Management, 207, 263-278.
Ross, D.W. 1995. Short-term impacts of thinning
ponderosa pine on pandora moth densities, pupal
weights, and phenology. Western-Journal-ofApplied-Forestry, 10, 91-94.
Ross, D.W. & Daterman, G.E. 1995. Efficacy of an
antiaggregation pheromone for reducing Douglas-fir
beetle, Dendroctonus pseudotsugae Hopkins
(Coleoptera: Scolytidae), infestation in high risk
stands. Canadian Entomologist, 127, 805-811.
Saab, V.A. & Dudley, J.G. 1998. Responses of cavitynesting birds to stand-replacement fire and salvage
logging in ponderosa pine/Douglas-fir forests of
southwestern Idaho. USDA Forest Service Rocky
Mountain Research Station Research Paper.
Safranyik, L., Shore, T.L., Carroll, A.L., & Linton, D.A.
2004. Bark beetle (Coleoptera : Scolytidae) diversity
in spaced and unmanaged mature lodgepole pine
(Pinaceae) in southeastern British Columbia. Forest
Ecology and Management, 200, 23-38.
Schmid, J.M. & Mata, S.A. 1992. Stand density and
mountain pine beetle-caused tree mortality in
ponderosa pine stands. Research Note RM-515, US
Department of Agriculture, Forest Service.
Schmid, J.M., Mata, S.A., & Olsen, W.K. 1995.
Microclimate and mountain pine beetles in two
ponderosa pine stands in the Black Hills. Research
Note RM-RN-532, US Department of Agriculture,
Forest Service.
Schowalter, T.D. & Withgott, J. 2001. Rethinking
insects. What would an ecosystem approach look
like? Conservation Biology in Practice, 2, 10-16.
Scott, D.W. 1996. Insect response to altered
landscapes: historic range of variation of insects.
USDA Forest Service Report BMZ-97-2. U.S.
Department of Agriculture, Forest Service, Pacific
Northwest Region, Wallowa-Whitman National
Forest, Blue Mountains Pest Management Zone,
LaGrande, OR.
Scott, D.W. 2000. Population analysis of Douglas-fir
tussock moth in northeastern Oregon and
southeastern Washington, 1999. USDA Forest
Service, Wallowa-Whitman National Forest,
LaGrande, OR.
Shepherd, R.F. 1994. Management Strategies for
Forest Insect Defoliators in British-Columbia. Forest
Ecology and Management, 68, 303-324.
Speer, J.H., Swetnam, T.W., Wickman, B.E., &
Youngblood, A. 2001. Changes in pandora moth
outbreak dynamics during the past 622 years.
Ecology, 82, 679-697.
Steeger, C. & Hitchcock, C.L. 1998. Influence of forest
structure and diseases on nest-site selection by redbreasted nuthatches. Journal of Wildlife
Management, 62, 1349-1358.
Swetnam, T.W., Wickman, B.E., Gene, P.H., & Baisan,
C.H. 1995. Historical patterns of western spruce
budworm and Douglas-fir tussock moth outbreaks
in the northern Blue Mountains, Oregon, since AD
1700. Research Paper - US Department of
Agriculture, Forest Service.
Torgersen, T.R. 2001. Defoliators in eastern Oregon
and Washington. Northwest Science, 75, 11-20.
Torgersen, T.R., Bull, E.L. 1995. Downed logs as
habitat for forest-dwelling ants—the primary prey of
pileated woodpeckers in northeastern Oregon.
Northwest Science, 69, 294-303.
Turner M.G., Romme, W.H., & Gardner, R.H. 1999.
Prefire heterogeneity, fire severity, and early postfire
plant reestablishment in subalpine forests of
Yellowstone National Park, Wyoming. International
Journal of Wildland Fire, 9, 21-36.
Yale University’s Global Institute of Sustainable Forestry
Waring, R.H., Savage, T., Cromack, K., & Rose, C.
1992. Thinning and Nitrogen-Fertilization in a
Grand Fir Stand Infested with Western Spruce
Budworm.
4. an Ecosystem Management
Perspective. Forest Science, 38, 275-286.
Whitehead, R.J. & Russo, G.L. 2005. “Beetle-proofed”
lodgepole pine stands in interior British Columbia
have less damage from mountain pine beetle.
Victoria, Canada: Pacific Forestry Centre, Canadian
Forest Service.
Wickman, B.E., Mason, R.R., & Paul, H.G. 1992.
Thinning and Nitrogen-Fertilization in a Grand Fir
Stand Infested with Western Spruce Budworm .2.
Tree Growth-Response. Forest Science, 38, 252264.
Wondzell, S.M. 2001. The influence of forest health
and protection treatments on erosion and stream
sedimentation in forested watersheds of eastern
Oregon and Washington. Northwest Science, 75,
128-140.
Zausen, G.L., Kolb, T.E., Bailey J.D., & Wagner, M.R.
2005. Long-term impacts of stand management on
ponderosa pine physiology and bark beetle
abundance in northern Arizona: A replicated
landscape study. Forest Ecology and Management,
218 (1-3), 291-305.
47
48
Scientific Basis for Forest Management in the U.S. Inland West
Annotated Bibliography
Old Growth Characterization
Agee, J.K. 1993. Fire Ecology of the Pacific Northwest Forests. Island Press, Washington, D.C.
Agee, J.K. (2003) Historical Range of Variability in Eastern Cascades Forests, Washington, USA. Landscape
Ecology, 18, 725-740.
This paper looks at the historical range of variability (HRV) in forest age structure for the central
eastern Cascades, WA. They discuss the fire return intervals and major plant association groups
(PAG). It has a good explanation of historic old-growth structure for these PAGs. For example, the
Ponderosa Pine-Douglas-fir PAG: frequent fire maintained old-growth stands at low density (70100
trees ha-1), little tree understory or CWD existed, etc. See paper pages 729733 for more detail.
Antos, J.A. & Parish, R. (2002) Dynamics of an Old-Growth, Fire-Initiated, Subalpine Forest in Southern Interior
British Columbia: Tree Size, Age, and Spatial Structure. Canadian Journal of Forest Research, 32, 1935-1946.
Reconstruction of history and dynamics of 330-year-old spruce-fir forest in southern interior BC.
Arsenault, A. (2003) A Note on the Ecology and Management of Old-Growth Forests in the Montane Cordillera.
Forestry Chronicle, 79, 441-454.
Bolsinger, C.L.W., Karen L. (1993) Area of Old-Growth Forests in California, Oregon and Washington. Forest
Service Resource Bulletin PNW-RB-197, 26 p.
1993 Forest Service publication looking at the area of old-growth in the Pacific Northwestincluding the area of interest. The document contains definitions of old-growth while strongly
highlighting the fact that there is no single definition for the term. The one thing all definitions
have in common is the presence of “large, old trees.” The document lists the classifications
used in the report and how they differ depending on ownership (USNF, National/State Parks,
Private, etc.).
Bond, B.J. & Franklin, J.F. (2002) Aging in Pacific Northwest Forests: A Selection of Recent Research. Tree
Physiology, 22, 73-76.
A review paper of a symposium on age-related changes in the structure and function of forests
in the PNW (held at Oregon State on 10/19/00). Symposium included research presented on
eastside
forests.
For
full
abstracts,
see
http://www.fsl.orst.edu/~bond/agesymposium_files/INDEX.htm.
Bonnicksen, T. (2000) America’s Ancient Forests John Wiley & Sons, Inc., New York.
Descriptive historical account of ancient forests, including those in the study area.
Annotated Bibliography
49
Boyden, S., Binkley, D., & Shepperd, W. (2005) Spatial and Temporal Patterns in Structure, Regeneration, and
Mortality of an Old-Growth Ponderosa Pine Forest in the Colorado Front Range. Forest Ecology and
Management, 219, 43-55.
A look at spatial and temporal patterns of structure, regeneration and mortality in an old-growth
ponderosa pine stand. While not in our study area (Colorado Front Range), this study presents
a potentially important consideration when defining old-growth in any system-associations in
both space and time. This study uses a combination of modeling and on-the-ground sampling.
Camp, A., Oliver, C., Hessburg, P., & Everett, R. (1997) Predicting Late-Successional Fire Refugia Pre-Dating
European Settlement in the Wenatchee Mountains. Forest Ecology and Management, 95, 63-77.
Looks at the historic range of ‘refugia’ stands in the inland Northwest and their potential impact
(as late-successional stands) as areas for habitat and as areas prone to insect/pathogen
outbreaks and wildfire. They used tree age, stand structure, and disturbance history to define
and identify refugial areas.
Covington, W.W., Fulé, P.Z., Hart, S.C., & Weaver, R.P. (2001) Modeling Ecological Restoration Effects on
Ponderosa Pine Forest Structure. Restoration Ecology, 9, 421-431.
This paper attempts to use an ecological process model (FIRESUM) to look at changes in stand
structure in a ponderosa pine ecosystem over a 100+ year time period. The model incorporates
surface fire disturbance and details the changes due to fire suppression and management shifts.
Study is outside region of interest (Arizonia), but incorporates interesting use of ecological modeling.
Covington, W.W. & Moore, M.M. (1994) Postsettlement Changes in Natural Fire Regimes and Forest Structure:
Ecological Restoration of Old-Growth Ponderosa Pine Forests. Journal of Sustainable Forestry, 2, 153-181.
Comparison of forest stand structure between pre-settlement and modern times in ponderosa
pine forests. On request from ILL...
DeLong, S.C. 1997. Ecological characteristics of forest remnants left by wildfire. Masters thesis, University of
Northern British Columbia. 94 p.
D’Eon, R.G. & Glenn, S.M. (2005) The Influence of Forest Harvesting on Landscape Spatial Patterns and OldGrowth-Forest Fragmentation in Southeast British Columbia. Landscape Ecology, 20, 19-33.
Study looking at landscape pattern and old-growth in eastern BC. Used 15 old-growth patch
indices.
Feller, M.C. (2003) Coarse Woody Debris in the Old-Growth Forests of British Columbia. Environmental Reviews, 11.
Review of the literature concerning CWD in old-growth forests in BC.
Franklin, Jerry F. and Dyrness C.T. 1988. Natural vegetation of Oregon and Washington. Corvallis, OR: Oregon
State University Press.
50
Scientific Basis for Forest Management in the U.S. Inland West
Franklin, J.F., Spies, T.A., Van Pelt, R., Carey, A.B., Thornburgh, D.A., Berg, D.R., Lindenmayer, D.B., Harmon,
M.E., Keeton, W.S., Shaw, D.C., Bible, K., and Chen, J. 2002. Disturbances and Structural Development of
Natural Forest Ecosystems with Silvicultural Implications, Using Douglas-fir Forests as an Example. Forest
Ecology & Management, 155, 399-423.
Abstract: Forest managers need a comprehensive scientific understanding of natural stand
development processes when designing silvicultural systems that integrate ecological and
economic objectives, including a better appreciation of the nature of disturbance regimes and
the biological legacies, such as live trees, snags, and logs, that they leave behind. Most
conceptual forest development models do not incorporate current knowledge of the: (1)
complexity of structures (including spatial patterns) and developmental processes; (2) duration
of development in long-lived forests; (3) complex spatial patterns of stands that develop in later
stages of seres; and particularly (4) the role of disturbances in creating structural legacies that
become key elements of the post-disturbance stands. We elaborate on existing models for stand
structural development using natural stand development of the Douglas-fir—western hemlock
sere in the Pacific Northwest as our primary example; most of the principles are broadly
applicable while some processes (e.g. role of epicormic branches) are related to specific species.
We discuss the use of principles from disturbance ecology and natural stand development to
create silvicultural approaches that are more aligned with natural processes. Such approaches
provide for a greater abundance of standing dead and down wood and large old trees, perhaps
reducing short-term commercial productivity but ultimately enhancing wildlife habitat,
biodiversity, and ecosystem function, including soil protection and nutrient retention.
Franklin, J.F. & Van Pelt, R. (2004) Spatial Aspects of Structural Complexity in Old-Growth Forests. Journal of
Forestry, 102, 22-29.
Frelich, L.E. & Reich, P.B. (2003) Perspectives on Development of Definitions and Values Related to Old-Growth
Forests. Environmental Reviews, 11. Perspectives on old-growth.
Not specific to study area, but interesting discussion of concept and definition of old-growth.
Fry, D.L. & Stephens, S.L. (2006) Influence of Humans and Climate on the Fire History of a Ponderosa Pine-Mixed
Conifer Forest in the Southeastern Klamath Mountains, California. Forest Ecology and Management, 223, 428-438.
Fire history of a ponderosa pine-mixed conifer forest in northeastern CA.
Garfin, G.M. and M.K. Hughes, 1996. “Eastern Oregon Divisional Precipitation and Palmer Drought Severity
Index from Tree-Rings.”
Report to the U.S. Forest Service Intermountain Research Station. USDA Forest Service
Cooperative Agreement PNW 90-174.
Helms, J.A. (2004) Old-Growth: What Is It? Journal of Forestry, 102, 8-13.
Critical look at issues of old-growth. From a Journal of Forestry issue specifically covering oldgrowth (April/May 2004, 102:3)
Annotated Bibliography
51
Hendrickson, O. (2003) Old-Growth Forests: Data Gaps and Challenges. Forestry Chronicle, 79, 645-651.
Hessburg, P.F., Smith, B.G., Kreiter, S.G., Miller, C.A., Salter, R.B., McNicholl, Ch.H., and Hann, W.J. 1999.
Historical and current forest and range landscapes in the Interior Columbia River Basin and portions of the
Klamath and Great Basins. Part 1. Linking vegetation patterns and landscape vulnerability to potential insect
and pathogen disturbances. Gen. Tech. Rep. PNW-GTR-458. USDA For. Serv., Pacific Northwest Res. Sta.
Portland, OR 357 pp.
Abstract: Management activities of the 20th century, especially fire exclusion, timber harvest,
and domestic livestock grazing, have significantly modified vegetation spatial patterns of forests
and ranges in the interior Columbia basin. Compositional patterns as well as patterns of living
and dead structure have changed. Dramatic change in vital ecosystem processes such as fire,
insect, and pathogen disturbances, succession, and plant and animal migration is linked to
recent change in vegetation patterns. Recent change in vegetation patterns is also a primary
reason for current low viability and threatened, endangered, or sensitive status of numerous
native plant and animal species. Although well intentioned, 20th-century management practices
have not accounted for the larger patterns of living and dead vegetation that enable forest
ecosystems to function in perpetuity and maintain their structure and organization through time,
or for the disturbances that create and maintain them. Knowledge of change in vegetation
patterns enhances resource manager and public awareness of patterns that better correspond
with current climate, site conditions, and native disturbance regimes, and improves
understanding of conditions to which native terrestrial species have already adapted. In this
study, we characterized recent historical and current vegetation composition and structure of
337 randomly sampled subwatersheds (9500 ha average size), in 43 of 164 total subbasins
(404 000 ha average size), selected by stratified random draw on all ownerships within the
interior Columbia River basin and portions of the Klamath and Great Basins (collectively referred
to as the basin). We compared landscape patterns, vegetation structure and composition, and
landscape vulnerability to 21 major insect and pathogen disturbances of historical and current
vegetation coverages. For each selected subwatershed, we constructed historical and current
vegetation maps from interpretations of 1932-66 and 1981-93 aerial photos, respectively. Areas
with homogeneous vegetation composition and structure were delineated as patches to a
minimum size of 4 ha. We then attributed cover types (composition), structural classes
(structure), and series-level potential vegetation types (site potential) to individual patches within
subwatersheds by modeling procedures. We characterized change in vegetation spatial patterns
by using an array of class and landscape pattern metrics and a spatial pattern analysis program.
Finally, we translated change in vegetation patterns to change in landscape vulnerability to major
forest pathogen and insect disturbances. Change analyses results were reported for provincescale ecological reporting units.
Forest and range ecosystems are significantly altered after their first century of active
management, but there is reason for guarded optimism. Large areas remain relatively
unchanged and intact, such as can be found on the east side of the Cascade Range in
Washington and in the central Idaho mountains, and these areas may provide an essential
“nucleus” for conservation strategies and ecosystem restoration. Strategies for improving the
health of basin ecosystems can build on existing strengths. Improved understanding of change
in vegetation patterns, causative factors, and links with disturbance processes will assist
managers and policymakers in making informed decisions about how to address important
ecosystem health issues.
52
Scientific Basis for Forest Management in the U.S. Inland West
Hessburg, P.F., Smith, B.G., Slater, R.B., Ottmar, R.d., and Vlvarado, E. 2000. Recent changes (1930s-1990s)
in spatial patterns of interior northwest forests. USA. Forest Ecology and Management 136: 53-83.
Abstract: We characterized recent historical and current vegetation composition and structure of
a representative sample of subwatersheds on all ownerships within the interior Columbia River
basin and portions of the Klamath and Great Basins. For each selected subwatershed, we
constructed historical and current vegetation maps from 1932 to 1966 and 1981 to 1993 aerial
photos, respectively. Using the raw vegetation attributes, we classified and attributed cover types,
structural classes, and potential vegetation types to individual patches within subwatersheds. We
characterized change in vegetation spatial patterns using a suite of class and landscape metrics,
and a spatial pattern analysis program. We then translated change in vegetation patterns to change
in patterns of vulnerability to wildfires, smoke production, and 21 major forest pathogen and insect
disturbances. Results of change analyses were reported for province-scale ecological reporting
units (ERUs). Here, we highlight significant findings and discuss management implications.
Twentieth century management activities significantly altered spatial patterns of physiognomies,
cover types and structural conditions, and vulnerabilities to fire, insect, and pathogen
disturbances. Forest land cover expanded in several ERUs, and woodland area expanded in
most. Of all physiognomic conditions, shrubland area declined most due to cropland expansion,
conversion to semi- and non-native herblands, and expansion of forests and woodlands. Shifts
from early to late seral conifer species were evident in forests of most ERUs; patch sizes of forest
cover types are now smaller, and current land cover is more fragmented. Landscape area in old
multistory, old single story, and stand initiation forest structures declined with compensating
increases in area and connectivity of dense, multilayered, intermediate forest structures. Patches
with medium and large trees, regardless of their structural affiliation are currently less abundant
on the landscape. Finally, basin forests are now dominated by shade-tolerant conifers, and
exhibit elevated fuel loads and severe fire behavior attributes indicating expanded future roles
of certain defoliators, bark beetles, root diseases, and stand replacement fires. Although well
intentioned, 20th-century management practices did not account for landscape-scale patterns
of living and dead vegetation that enable forest ecosystems to maintain their structure and
organization through time, or for the disturbances that create and maintain them. Improved
understanding of change in vegetation spatial patterns, causative factors, and links with
disturbance processes will assist managers and policymakers in making informed decisions
about how to address important ecosystem health issues.
Hessburg, P.F. & Agee, J.K. (2003) An Environmental Narrative of Inland Northwest United States Forests, 18002000. Forest Ecology and Management, 178, 23-59.
Environmental and forest history of inland Northwest forests from 18002000 (using remote
sensing). Impresses the role of fire in shaping forest structure and function. Also maps potential
historic vegetation groups throughout region. Further understanding of how they define oldgrowth needed.
Hessburg, P.F., Agee, J.K., & Franklin, J.F. (2005) Dry Forests and Wildland Fires of the Inland Northwest USA:
Contrasting the Landscape Ecology of the Pre-Settlement and Modern Eras. Forest Ecology and Management,
211, 117-139.
Interesting paper looking at landscape ecology of dry, inland Northwest forests. Specifically addresses fire history
and past conditions of ponderosa pine-dominated stands. Contrasts the structure and function of pre-
Annotated Bibliography
53
settlement conditions with modern conditions. Contains nice images, maps and explanations of current and
historical stand conditions, but little explanation on how old-growth is defined (little discussion on groundtruthing, etc.).
Hunter Jr, M.L. & White, A.S. (1997) Ecological Thresholds and the Definition of Old-Growth Forest Stands.
Natural Areas Journal, 17, 292-296.
Synthesis of published literature concerning thresholds for old-growth (using patterns of NPP,
biomass, gap size and % of stands in gaps, volume of CWD, spp richness and composition).
They found no clear thresholds for determining old-growth.
Irvine, J., Law, B.E., Anthoni, P.M., & Meinzer, F.C. (2002) Water Limitations to Carbon Exchange in Old-Growth
and Young Ponderosa Pine Stands. Tree Physiology, 22, 189-196.
Comparison of water limitations and carbon exchange in old and young ponderosa pine stands
(eastern Oregon). Old-growth stands consisted of two, mixed age classes-50 and 250 years.
Understory was sparse and none of the stands had previously been logged.
Irwin, L.L., Fleming, T.L., & Beebe, J. (2004) Are Spotted Owl Populations Sustainable in Fire-Prone Forests?
Journal of Sustainable Forestry, 18, 1-28.
A critical look at spotted owl habitat preference in the eastern Cascade, WA. Authors found a
negative relationship between late-successional forest and territory selection. An interesting look
at issues directly related to old-growth policy and habitat selection.
Johnson, E.A., Miyanishi, K., & Weir, J.M.H. (1995) Old-Growth, Disturbance, and Ecosystem Management.
Canadian Journal of Botany-Revue Canadienne De Botanique, 73, 918-926.
Kaufmann, M. (1996) To Live Fast or Not: Growth, Vigor and Longevity of Old-Growth Ponderosa Pine and
Lodgepole Pine Trees. Tree Physiology, 16, 139-144.
Research on growth patterns in relation to leaf area for old ponderosa and lodgepole pines. In
most cases, trees were >200 yrs-old. Authors found a wide range of early-and late-successional
growth patterns that can lead to old-growth. Study outside of area of interest (Colorado).
Kranabetter, J.M., Friesen, J., Gamiet, S., & Kroeger, P. (2005) Ectomycorrhizal Mushroom Distribution by Stand
Age in Western Hemlock -Lodgepole Pine Forests of Northwestern British Columbia. Canadian Journal of
Forest Research, 35, 1527-1539.
Research looking at species richness of ectomycorrhizzal fungal on submesic western hemlocklodgpole pine stands in BC. Found much higher richness in older stands. Could potentially be
an indicator of old-growth?
Landres, P., Morgan, P., & Swanson, F. (1999) Overview of the Use of Natural Variability Concepts in Managing
Ecological Systems. Ecological Applications, 9, 1179-1188.
Langston, N. (1996) Forest Dreams, Forest Nightmares: The Paradox of Old Growth in the Inland West University
of Washington Press, Seattle, WA.
54
Scientific Basis for Forest Management in the U.S. Inland West
Langston, N. (2000) When Sound Science Is Not Enough. Regulating the Blues. Journal of Forestry, 98, 31-35.
A history of early forestry policy and practice in the inland west and how it relates to past and
present old-growth (particularly the Blue Mountains, OR).
Laughlin, D.C., Bakker, J.D., Stoddard, M.T., Daniels, M.L., Springer, J.D., Gildar, C.N., Green, A.M., & Covington,
W.W. (2004) Toward Reference Conditions: Wildfire Effects on Flora in an Old-Growth Ponderosa Pine Forest.
Forest Ecology and Management, 199, 137-152.
Authors propose the concept of reference conditions. Study takes place outside the area of
interest (N. Arizonia), but discussed the idea of using stands that mimic natural disturbance
regimes (both human and natural) to better understand natural processes and forest structure.
Ponderosa pine systems are focus of research.
Lee, D.C. and Irwin, L.L. 2005. Assessing risks to spotted owls from forest thinning in fire-adapted forests of the
western United States. Forest Ecology And Management, 211, 191-209.
Abstract: Concern for viable spotted owl (Strix occidentalis) populations has played prominently
in the management of western forests in the United States. Historically, much of the debate has
focused on the impacts of commercial timber harvest. Increasingly, the conflict is shifting to the
habitat needs of owls versus the need for active management of fire-adapted forest ecosystems
to reduce the occurrence of uncharacteristic wildland fire that threatens multiple resource
values. While some authors have called for active fuels management within the range of spotted
owls, concerns remain over potential effects of less intensive, but more extensive, fuel reduction
activities (i.e., thinning and prescribed burning). Reconciling fire and fuels management with
owl conservation requires rigorous analysis of both the short- and long-terms risks of action
versus no action. We use published literature and data from the southern Sierra Nevada to
examine the potential effects of landscape-level reductions in canopy cover (CC) on owl
occupancy and reproduction. Using a combination of population data, canopy cover
measurements, and forest simulation models, we show that modest fuels treatments in the
Sierra Nevada would not be expected to reduce canopy cover sufficiently to have measurable
effects on owl reproduction. Sixty-year simulations predict that mechanical thinning or
mechanical thinning plus fuel-break construction treatments in combination with either no fire
or mixed-lethal fire scenarios will not degrade canopy conditions in productive owl territories, nor
impede improvement of non-productive territories. In contrast, lethal fire simulations produced
a pronounced and lasting negative effect. Our analysis supports the hypothesis that habitat
needs for owl reproduction can be incorporated in developing effective fire and fuels
management strategies that lessen the chances of uncharacteristic wildfire. Projections of future
population trends are tempered by the knowledge that non-habitat factors such as variations in
weather profoundly affect population dynamics.
Lesica, P. (1996) Using Fire History Models to Estimate Proportions of Old Growth Forest in Northwest Montana,
USA. Biological Conservation, 77, 33-39.
Reconstruction of pre-settlement stand-age distributions in western MT using fire history and
negative exponential models. Old-growth is defined as 200 yrs-old. Results indicate presettlement old-growth occupied 20-50% of forest ecosystems.
Annotated Bibliography
55
Lund, H.G. (2005) Definitions of Old Growth, Pristine, Climax, Ancient Forests, Degradation, Desertification,
Forest Fragmentation, and Similar Terms., Vol. 2006. Website-Forest Information Services.
This website is an overview of terms related to old-growth found in the literature. It highlights the
difficulty in accurately defining what old-growth really is. It lists hundreds of different definitions116 for ‘old-growth’ alone-culled from the literature.
MacKinnon, A. & Vold, T. (1998) Old-Growth Forests Inventory for British Columbia, Canada. Natural Areas
Journal, 18, 309-318.
Old-growth forest inventory for BC (1998) using very general definition. For interior BC, oldgrowth = trees greater than 140-years-old for most and greater 120-years-old for lodgepole pine.
Mast, J.N., Fule, P.Z., Moore, M.M., Covington, W.W., & Waltz, A.E.M. (1999) Restoration of Presettlement Age
Structure of an Arizona Ponderosa Pine Forest. Ecological Applications, 9, 228-239.
Out of study area (Arizonia), but an interesting paper on pre-settlement age distribution and
structure of an old-growth ponderosa pine stand. They used both living and dead
dendrochronological samples, resulting in ‘more accurate’ reconstruction of age class (with 20%
of trees >200 yrs-old and ranging in age up to 340 yrs-old).
McElhinny, C., Gibbons, P., Brack, C., & Bauhus, J. (2005) Forest and Woodland Stand Structural Complexity:
Its Definition and Measurement. Forest Ecology and Management, 218, 1-24.
This paper looks at structural complexity at the stand level. It is not specific to our study region,
but proposes guidelines for measuring and creating an index of structural complexity.
Mehl, C. & Haufler, J. (2003). Preserving and Restoring the Old-Growth Ponderosa Pine Ecosystem in Idaho, Rep.
No. Idaho Fish & Game WCRP Project R-1-6-0203. Ecosystem Management Research Institute, Seeley Lake, MT.
Prioritization and ranking of ponderosa pine stands in Idaho. Study completed by the Ecosystem
Management Institute in Seeley Lake, MT. Funded by Idaho Fish & Game. Study incorporates
mapping of historic distributions as well as natural disturbance regime patterns. See website for
more info: http://www.emri.org/Projects/id_pipo.htm
Metlen, K.L. & Fiedler, C.E. (2006) Restoration Treatment Effects on the Understory of Ponderosa Pine/DouglasFir Forests in Western Montana, USA. Forest Ecology and Management, 222, 355-369.
A look at restoration of structure and function of ponderosa pine forests towards more ‘historically
sustainable conditions’ (western MT). May be important in looking at stands that have been
disturbed in the past, but may be approaching or will one day resemble old-growth. This
particular study looked at a stand that had been logged around 1900.
Moeur, M., Martin, J.R., Demeo, T., Alegria, J., Spies, T., Cohen, W., Healey, S., Hemstrom, M., Cissel, J.,
Browning, J., & Warbington, R. (2005) Status and Trend of Late-Successional and Old-Growth Forest. USDA
Forest Service General Technical Report PNW, 1-142.
Report on the status and trends of late-successional and old-growth forest on Federal lands
covered under the Northwest Forest Plan (NWFP). This includes lands managed by the Forest
56
Scientific Basis for Forest Management in the U.S. Inland West
Service, BLM, and Park Service. Review is for the time period of 1994-2003. Contains definitions
of old-growth used in the report and as defined in the NWFP. The physiographic provinces
outlined in the NWFP of interest to this study are (as numbered in the document): 4. WA Eastern
Cascades; 6. OR Eastern Cascades; 12. California Cascades.
Mosseler, A., Thompson, I., & Pendrel, B.A. (2003) Overview of Old-Growth Forests in Canada from a Science
Perspective. Environmental Reviews, 11.
Overview of a symposium on the conservation of old-growth forests in Canada. Not specific to
the study region.
Norheim, Robert A. 1998. Why so different? Examining the techniques used in two old growth mapping projects.
In Sensing and Managing the Environment: Proceedings, 1998 International Geoscience and Remote Sensing
Symposium (IGARSS ‘98). Institute of Electrical and Electronics Engineers, Seattle. Vol. 3, pp. 1620-1622.
Abstract: In 1990, two different projects simultaneously mapped old growth in National Forests
in the northern spotted owl region in the Pacific Northwest. The two projects used significantly
different technology and techniques, and found amounts of old growth acreage that differed by
a factor of two. This paper investigates the procedures used in each project to determine the
sources of the differing results, using four of the forests mapped as a case study. The project
carried out by Pacific Meridian Resources (PMR) for the U.S. Forest Service (USFS) used
Landsat TM imagery and sophisticated image processing techniques, whereas The Wilderness
Society project relied primarily on photo-interpretation but also used Landsat MSS imagery. The
USFS project quantitatively mapped different size and structure classes, but The Wilderness
Society’s project attempted to qualitatively categorize several variations of old growth. The
projects operated under tremendous deadline pressure, had vastly different budgets, used very
different hardware and software systems and had very different techniques for ground truth and
accuracy assessment. Thus, despite the fact that their goals were identical these factors caused
significantly different results.
Ohlson, T.H. 1996. Fire regimes of the ponderosa pine – Douglas-fir/beardless bluebunch wheatgrass plant
association in the Methow Valley of north central Washington. MS thesis. Washington State University. 87 p.
Perera, A.H., Baldwin, D.J.B., Yemshanov, D.G., Schnekenburger, F., Weaver, K., & Boychuk, D. (2003) Predicting
the Potential for Old-Growth Forests by Spatial Simulation of Landscape Ageing Patterns. Forestry Chronicle,
79, 621-631.
Perry, D., Henjum, M., Karr, J., Bottom, J., Bendarz, S., Wright, S., Beckwitt, S., & Beckwitt, E. (1995) Interim
Protection for Late-Successional Forests, Fisheries, and Watersheds: A Summary of the Report of the Eastside
Forests Scientific Society Panel 103-114 in Symposium proceedings, Ecosystem Management in Western
Interior Forests. Dept. of Natural Resources, Washington State University, Pullman, WA.
A report on late-successional forests of the eastside by Washington State University.
Picken, E. (2005). Lost Forests: An Investigative Report on the Old-Growth of North Idaho. The Lands Council,
Spokane, WA.
Report published by the Spokane, WA based non-profit The Lands Council. Attempts to look critically at the
Forest Service’s mapping of old-growth in the inland west (mainly WA and ID). The Idaho Panhandle National
Annotated Bibliography
57
Forest (IPNF) Forest Plan stipulates that the FS maintain a minimum of 10% of forest inventory as old-growth.
The FS definition for old-growth (generally) is 10 trees over 21” DBH per acre and greater than 150-years-old.
A FS inventory found 12% as old-growth, but the Lands Council disputes this and states the number to be well
below.
Pruyn, M.L., Gartner, B.L., & Harmon, M.E. (2002) Respiratory Potential in Sapwood of Old Versus Young
Ponderosa Pine Trees in the Pacific Northwest. Tree Physiology, 22, 105-116.
Quigley, T.M., Haynes, R.W., & Graham, R.T. (1996) Integrated Scientific Assessment for Ecosystem Management
in the Interior Columbia Basin and Portions of the Klamath and Great Basins. General Technical Report -US
Department of Agriculture, Forest Service.
Extensive scientific assessment report on the Columbia Basin-the Integrated Scientific
Assessment for Ecosystem Management for the Interior Columbia Basin. See the following link
to download complete report: http://www.fs.fed.us/pnw/publications/icbemp.shtml
Reynolds, K.M. & Hessburg, P.F. (2005) Decision Support for Integrated Landscape Evaluation and Restoration
Planning. Forest Ecology and Management, 207, 263-278. Historic range of variability and landscape
evaluation in eastern WA & OR.
Schellhaas, R., Camp, Spurbeck, D., and Keenum, D. 2000. Report to the Colville National Forest on the results
of the South Deep watershed fire history research. USDA Forest Service Pacific Northwest Research Station
Wenatchee Forestry Sciences Lab.
Abstract: We reconstructed the fire history for the portion of the South Deep watershed managed
by the Colville National Forest. This fire history encompasses the period between 1683 and
1910, and is based on 773 individual fire scars from 168 cross sections and 215 remnant tree
cores. We stratified the landscape by aspect into smaller, more homogeneous sampling units.
We also separated this fire history into two periods. The pre-settlement era (prior to 1860)
documents fire frequency and extent prior to the land clearing, livestock grazing, and road
building influences of Eurosettlement. The settlement era (1860 - 1910) reflects fire regimes
during the period of active settlement but excludes those years following the onset of active fire
suppression. We did, however, document the dates and extent of fires that occurred in the
watershed after 1910.
During the pre-settlement era (pre 1860) fires were less frequent and larger than during
Eurosettlement (1860-1910). For the watershed as a whole, mean fire frequency prior to
settlement was 5.9 years; during settlement MFFI dropped to 2.5 years. For individual aspect
polygons, pre-settlement MFFIs ranged between 11 and 39.4 years. During settlement, that
range decreased to between 4.5 and 25.5 years. Point-based estimates of fire frequency
calculated at 23 locations ranged between 15.7 and 46.7 years. Pre-settlement fire size
averaged 520 acres, decreasing to 337 acres during the settlement era. Estimated fire size was
highly variable, with a range of 28 to nearly 15,000 acres. Jaccard Similarity Indices computed
for adjacent polygons separated by either a valley bottom or ridgeline indicate that fire events
within aspect polygons were not statistically independent; fires frequently burned from one
polygon across a topographic boundary into an adjacent polygon.
The variability inherent within the historical fire regime of the South Deep watershed suggests
historical vegetation patterns that were correspondingly variable. Point-based estimates of fire
58
Scientific Basis for Forest Management in the U.S. Inland West
frequency show some areas experienced fires 2 to 3 times more frequently than did other areas.
Area-based estimates of fire frequency suggest this range of variability may be even greater.
We located one stand that probably has not burned since it established following a fire in 1751.
Overall, however, our data indicate fires occurred more frequently and were less severe than
previously was believed for northeastern Washington’s mesic mixed conifer forests.
Schellhaas, R., Spurbeck, D., Keenum, D. and Conway, A. 2003. Report to the Okanogan and Wenatchee
National Forests on the results of the Twentymile Planning Area fire history research. USDA Forest Service
Pacific Northwest Research Station Wenatchee Forestry Sciences Lab.
Shinneman, D.J. & Baker, W.L. (1997) Nonequilibrium Dynamics between Catastrophic Disturbances and OldGrowth Forests in Ponderosa Pine Landscapes of the Black Hills. In Conservation Biology, Vol. 11, pp.
1276-1288.
A discussion of the importance of determining the historic range of variability when thinking
about ecosystem management. Stresses the importance of not only thinking about low-intensity,
frequent disturbance effects on ponderosa pine stands, but also the existence of past highintensity disturbance regimes. Study is focused outside of area of interest (Black Hills), but
stresses the importance of multiple forms of disturbance impacting forest structure.
Spies, T.A. (2004) Ecological Concepts and Diversity of Old-Growth Forests. Journal of Forestry, 102, 14-21.
Review paper highlights the importance of having a multiscale perspective with attempting to
understanding old-growth systems. It stresses the many different definitions of ‘old-growth’ and
the importance of focusing on what these different definitions share-i.e. spatial heterogeneity.
Also highlight that any successful definition must incorporate developmental stages, and not just
growth. Part of a Journal of Forestry issues related specifically to old-growth
Spies, T., Hemstrom, M., Youngblood, A., and Hummel, S. 2006. Conserving old-growth forest diversity in
disturbance prone landscapes. Conservation Biology, 20, 351-362.
Abstract: A decade after its creation, the Northwest Forest Plan is contributing to the
conservation of old-growth forests on federal land. However, the success and outlook for the plan
are questionable in the dry provinces, where losses of old growth to wildfire have been relatively
high and risks of further loss remain. We summarize the state of knowledge of old-growth forests
in the plan area, identify challenges to conserve them, and suggest some conservation
approaches that might better meet the goals of the plan. Historically, old-growth forests in these
provinces ranged from open, patchy stands, maintained by frequent low-severity fire, to a mosaic
of dense and open stands maintained by mixed-severity fires. Old-growth structure and
composition were spatially heterogeneous, varied strongly with topography and elevation, and
were shaped by a complex disturbance regime of fire, insects, and disease. With fire suppression
and cutting of large pines ( Pinus spp.) and Douglas-firs (Pseudotsuga menziesii [Mirbel]
Franco), old-growth diversity has declined and dense understories have developed across large
areas. Challenges to conserving these forests include a lack of definitions needed for planning
of fire-dependent old-growth stands and landscapes, and conflicts in conservation goals that can
be resolved only at the landscape level. Fire suppression has increased the area of the dense,
older forest favored by Northern Spotted Owls (Strix occidentalis caurina) but increased the
probability of high-severity fire. The plan allows for fuel reduction in late-successional reserves;
fuel treatments, however, apparently have not happened at a high enough rate or been applied
Annotated Bibliography
59
in a landscape-level approach. Landscape-level strategies are needed that prioritize fuel
treatments by vegetation zones, develop shaded fuel breaks in strategic positions, and thin
and apply prescribed fire to reduce ladder fuels around remaining old trees. Evaluations of
the current and alternative strategies are needed to determine whether the current reservematrix approach is the best strategy to meet plan goals in these dynamic landscapes.
USDA (United States Department of Agriculture) Forest Service and BLM (Bureau of Land Management) 1994.
Record of decision for amendments to Forest Service and Bureau of Land Management planning documents
within the range of the Northern Spotted Owl. USDA Forest Service and BLM, Washington, DC. 74 p.
USFS. 1993. Region 6 Interim Old-Growth Definitions for the Douglas-fir Series, Grand Fir/White Fir Series,
Interior Douglas-fir Series, Lodgepole Pine Series, Pacific Silver Fir Series, Ponderosa Pine Series, Port Orford
Cedar Series, Tanoak (Redwood) Series, Western Hemlock Series. USDA Forest Service, Pacific Northwest
Region, Portland, Oregon.
WSDNR. 2005. Definition and Inventory of Old Growth Forests on DNR-Managed State Lands. Washington State
Department of Natural Resources. Olympia, WA.
Wells, R.W., Lertzman, K.P., & Saunders, S.C. (1998) Old-Growth Definitions for the Forests of British Columbia,
Canada. Natural Areas Journal, 18, 279-292.
Potentially important paper. Discussion on importance of defining old-growth. Focused on BC.
Wright, C.S. & Agee, J.K. (2004) Fire and Vegetation History in the Eastern Cascade Mountains, Washington.
Ecological Applications, 14, 443-459.
Reconstruction of 433-year fire history in eastern Cascades, WA. Highlights dramatic declines
in fire frequency and size post-1900.
Youngblood, A. (2001) Old-Growth Forest Structure in Eastern Oregon and Washington. Northwest Science,
75, 110-118.
Discusses issues related specifically to forest health and productivity in eastern OR and WA.
Youngblood, A., Max, T., & Coe, K. (2004) Stand Structure in Eastside Old-Growth Ponderosa Pine Forests of
Oregon and Northern California. Forest Ecology and Management, 199, 191-217.
Important paper looking at quantitative metrics of horizontal and vertical structural attributes
of eastside old-growth ponderosa pine. They measured: all stems 15 cm in height; spatial
distribution using Ripley’s K function; CWD using strip-plot method.
Zenner, E.K. (2004) Does Old-Growth Condition Imply High Live-Tree Structural Complexity? Forest Ecology and
Management, 195, 243-258.
Characterization of structural complexity of old-growth stands in the central western Cascades,
OR. While not in the study area, this paper uses the following indices to quantify stand
characteristics: 1. ‘index of old-growth’ to determine old-growth condition; 2. ‘structural
60
Scientific Basis for Forest Management in the U.S. Inland West
complexity index (SCI)‘ to determine structural complexity; 3. ‘Ripley’s K function’ to determine
spatial tree distribution patterns. The positive relationship they found between old-growth and
structural complexity may not carry over to fire-dominated, eastern old-growth, but the indices
can perhaps be used or modified to study east-side forests.
Zenner, E.K. (2005) Investigating Scale-Dependent Stand Heterogeneity with Structure-Area-Curves. Forest
Ecology and Management, 209, 87-100. Further information on indices presented in Zenner (2004).
61
Annotated Bibliography
Annotated Bibliography
Post Fire Salvage Logging
Agee, J.K. (1993) Fire Ecology of Pacific Northwest Forests Island Press, Washington, D.C.
This book is intended to provide a natural baseline that wildland managers, or those interested
in wildland management, may use in understanding the effects of natural or altered fire regimes
in the western United States. It provides detailed information on the effects of fire on western
vegetation and environments, with several chapters dedicated to specific vegetation types.
Akay, A.E., Sessions, J., Bettinger, P., Toupin, R., & Eklund, A. (2006) Evaluating the Salvage Value of Fire-Killed
Timber by Helicopter - Effects of Yarding Distance and Time Since Fire. Western Journal of Applied Forestry,
21, 102-107.
Recently, large areas of federal lands in the western United States have been subject to wildfire.
Concerns about hastening restoration, soil disturbance, and road building have prompted
consideration of helicopter logging. Normal planning procedures on federal lands are not
sensitive to the rapid decline in the recoverable economic value of fire-killed timber. The
economic value of fire-killed timber is dependent on logging costs and time since tree death. A
model is developed to calculate value of fire-killed timber as a function of time since death and
yarding distance using helicopters as the preferred logging method. Applications of the method
to tactical planning are discussed.
Anonymous (2000) After the fire: The effects of salvage logging. Journal of Forestry, 98, A1-A3.
This paper provides a short synthesis of two previous works, both General Technical Reports by
the USDA Forest Service, on the ecological and social implications of post-fire logging. It
provides key points and conclusions.
Beschta, R.L., Frissell, C.A., Gresswell, R.E., Hauer, F.R., Karr, J.R., Minshall, G.W., Perry, D.A., & Rhodes, J.J.
(1995) Wildfire and Salvage Logging: Recommendations for Ecologically Sound Post-Fire Salvage Management
and Other Post-Fire Treatments on Federal Lands in the West, Unpublished Work. 16 pgs.
Human intervention on the post-fire landscape may substantially or completely delay recovery,
remove the elements of recovery, or accentuate the damage. Many such adverse consequences
are difficult or impossible to predict or foresee in specific situations. In this light there is little
reason to believe that post-fire salvage logging has any positive ecological benefits, particularly
for aquatic ecosystems. There is considerable evidence that persistent, significant adverse
environmental impacts are likely to result from salvage logging, based on many past cases of
salvage projects, plus our growing knowledge of ecosystem functions and land-aquatic linkages.
These impacts include soil compaction and erosion, loss of habitat for cavity nesting species,
loss of structurally and functionally important large woody debris.
62
Scientific Basis for Forest Management in the U.S. Inland West
Beschta, R.L., Rhodes, J.J., Kauffman, J.B., Gresswell, R.E., Minshall, G.W., Karr, J.R., Perry, D.A., Hauer, F.R.,
& Frissell, C.A. (2004) Postfire management on Forested Public Lands of the Western United States.
Conservation Biology, 18, 957-967.
The authors examine, via the published literature and their collective experience, the ecological
effects of some common postfire treatments. Based on this examination, they recommend
postfire restoration activities that include retention of large trees, rehabilitation of firelines and
roads, and, in some cases, planting of native species. They recommend against seeding exotic
species, livestock grazing, placement of physical structures in and near stream channels,
ground-based postfire logging, removal of large trees, and road construction. Practices that
adversely affect soil integrity, persistence or recovery of native species, riparian functions, or
water quality generally impede ecological recovery after fire. Although research provides a basis
for evaluating the efficacy of postfire treatments, there is a continuing need to increase our
understanding of the effects of such treatments within the context of societal and ecological
goals for forested public lands of the! western United States.
Brown, J.K., Reinhardt, E.D., & Kramer, K.A. (2003) Coarse Woody Debris: Managing Benefits and Fire Hazard
in the Recovering Forest (ed U.F. Service), pp. 1-20. Rocky Mountain Research Station.
Management of coarse woody debris following fire requires consideration of its positive and
negative values. The ecological benefits of coarse woody debris and fire hazard considerations
are summarized. This paper presents recommendations for desired ranges of coarse woody
debris. Example simulations illustrate changes in debris over time and with varying management.
Goals of paper are: 1. identify a range of CWD quantities that provides for positive values and
avoids excessive fire hazard, and 2. illustrate how simulation of the effects of various
management alternatives on CWD over long periods can assist in planning.
Brown, R. (2000). Thinning, Fire and Forest Restoration: A Science-Based Approach for National Forests of the
Interior Northwest. Defenders of Wildlife.
The author explores the scientific basis for what is known, how to proceed, and what information
is still needed in terms of forest alteration and restoration in the interior Northwest. This paper
is an attempt to review the most pertinent scientific literature, merge these findings with policy
requirements, and provide recommendations on how best to proceed.
Brown, R.T., Agee, J.K., & Franklin, J.F. (2004) Forest restoration and fire: Principles in the context of place.
Conservation Biology, 18, 903-912.
There has been recent debate regarding the types of thinning and fire and where they are used
as a component of forest management. The authors offer a prioritization for fuels reduction in
different fire-regimes and a ranking of thinning practices.
Yale University’s Global Institute of Sustainable Forestry
63
Bury, B. (2004) Wildfire, Fuel Reduction, and Herpetofaunas across Diverse Landscape Mosaics in Northwestern
Forests. Conservation Biology, 18, 968-975.
The objective of this paper was to synthesize our current knowledge of wildfire and the legacy
of past logging that affects reptiles and amphibians and to explore means to better protect
resident wildlife in the process of restoring fire to habitats in western forests. Most forest
amphibians west of the Cascade Mountain crest are associated with cool, cascading streams or
coarse woody material on the forest floor, which are characteristics of mature forests. Calls for
prescribed fire and thinning to reduce fuel loads will remove large amounts of coarse woody
material from forests, which reduces cover for amphibians and alters nutrient inputs to streams.
Preliminary evidence suggests no negative effects of wildfire on terrestrial amphibians, but
stream amphibians decrease following wildfire. Most reptiles are adapted to open terrain, so
fire usually improves their habitat. Today, the challenge is to maintain biodiversity in western
forests in the face of intense political! pressures designed to “prevent” catastrophic fires. We
need a dedicated research effort to understanding how fire affects biota and to proactively
investigate outcomes of fuel-reduction management on wildlife in western forests.
Camp, A. (2002) Damage to residual trees by four mechanized harvest systems operating in small-diameter,
mixed-conifer forests on steep slopes in northeastern Washington: A case study. Western Journal of Applied
Forestry, 17, 14-22.
Abstract: Dense stands of small-diameter timber present unique challenges for land managers.
In the inland West, trees in high-density stands often grow slowly and may be at risk to insects,
diseases, and catastrophic fires. In 1996, the U.S. Congress recognized a need to address forest
health issues and stimulate local resource-based economies in northeastern Washington. Funds
were provided for “implementation and evaluation of controlled silvicultural treatment in
designated, fire-generated, overstocked, small-diameter stands” (U.S. Congress House Report
104-625).
As part of this Congressionally mandated research effort, four harvest units, each thinned to a
20 ft spacing using different harvesting technologies, were surveyed for damage prior to and
following commercial thinning. Comparisons were made among the systems tested to assess
damage to the residual stand. Overall incidence of wounds, incidence of wounds in different size
and severity classes, and wound locations were compared. Each system performed better when
judged by some criteria than by others. In general, cut-to-length processing caused less damage
to the residual stand than whole-tree harvest; skyline yarding was less damaging than forwarder
yarding. Some of the damage may have been a function of the silvicultural prescription and
season of harvest. Appropriate silvicultural prescriptions and harvesting technologies can reduce
wounding to acceptable levels.
Carroll, M.S., Findley, A.J., Blatner, K.A., Mendez, S.R., Daniels, S.E., & Walker, G.B. (2000) Social Assessment
for the Wenatchee National Forest Wildfires of 1994: Targeted Analysis for the Leavenworth, Entiat, and Chelan
Ranger Districts. Gen. Tech. Rep. PNW-GTR-479, 114 pp. Pacific Northwest Research Station.
Abstract: A purposive social assessment across three communities explored reactions of local
residents to wildfires in the Wenatchee National forest in north-central Washington. Research
concentrated on identifying the diversity of fundamental beliefs and values held by local
residents about wildlife and forest management. Semistructured interviews were conducted with
64
Scientific Basis for Forest Management in the U.S. Inland West
people representing a diverse set of values, attachments to the National Forest, and beliefs
about forest management. For each of the three communities, an indepth discussion described
social dynamics relative to fire recovery in the National Forest by juxtaposing value orientations
and beliefs across 15 fire recovery issues. Conclusions targeted improved public involvement
processes in the aftermath of severe ecological disturbances and traumatic human experiences.
Committee on Resources, US House of Representatives. 2006. Oversight Hearing on Scientific Research and the
Knowledge-base concerning Forest Management Following Wildfires and Other Major Disturbances.
http://resourcescommittee.house.gov/archives/109/ffh/022406.htm. February 24, 2006.
Panels of experts present testimony regarding management objectives following fire and
research on post-fire intervention.
Dellasala, D.A., Williams, J.E., Williams, C.D., & Franklin, J.F. (2004) Beyond Smoke and Mirrors: a Synthesis of
Fire Policy and Science. Conservation Biology, 18, 976-986.
Authors provide a social and ecological context for summarizing a special issue on fires,
including general guidelines and principles for managers concerned about balancing the risks
of inaction against the risks of action over extensive areas. The authors note that fire is extremely
variable, has multiple causes, and requires ecological solutions that are sensitive to spatial scale
and context. Therefore, different forest types have different fire regimes and require
fundamentally different fire- management policies. Furthermore, to restore or maintain ecological
integrity, including the role of fire, treatments need to be tailored to site-specific conditions with
an adaptive approach. The authors provide a conceptual framework for prioritizing fuel
treatments and restoration activities in the wildlands-urban intermix versus those in wildland
areas farther from human settlement.
DeLong, S.C., Arocena, J.M., & Massicotte, H.B. (2003) Structural characteristics of wet montane forests in eastcentral British Columbia. The Forestry Chronicle, 72, 342-351.
The objective of this paper was to develop criteria that could be used to assess the extent to
which managed stands approximate the structural characteristics of natural stands. The authors
emphasize management following disturbance, particularly fire. They also address the use of
post fire logging in the region.
DeLong, S.C. & Tanner, D. (1996) Managing the pattern of forest harvest: lessons from wildfire. Biodiversity and
Conservation, 5, 1191-1205.
The intent of this paper is to examine differences and similarities between wildfire and harvested
areas within a portion of the sub-boreal landscape. The author hypothesizes that wildfires are
becoming smaller and less frequent, clearcutting has supplanted wildfire as the dominant
disturbance agent in terms of area affected, individual clearcuts are spatially different from
individual wildfires, and the landscape mosaic produced by clearcutting varies from that
produced by wildfire.
Annotated Bibliography
65
Donato, D.C., Fontaine, J.B., Campbell, J.L., Robinson, W.D., Kauffman, J.B., & Law, B.E. (2006) Post-Wildfire
Logging Hinders Regeneration and Increases Fire Risk. Science, 311, 352.
Presents data from a study of early conifer regeneration and fuel loads after the 2002 Biscuit
Fire, Oregon, USA, with and without postfire logging. Data show that postfire logging, by
removing naturally seeded conifers and increasing surface fuel loads, can be counterproductive
to goals of forest regeneration and fuel reduction. In addition, forest regeneration is not
necessarily in crisis across all burned forest landscapes.
Duncan, S. (2002) Postfire Logging: Is it Beneficial to a Forest?, pp. 1-5. USDA Forest Service PNW Research
Station.
Presents key points of arguments for and against postfire logging. Key Findings: The immediate
environmental effects of postfire logging depend on the severity of the burn, slope, soil texture
and composition, the presence or building of roads, type of logging system, and postfire weather
conditions; postfire logging can cause significant changes in the abundance and nest density
of cavity-nesting birds, particularly those attracted to recently burned forests; the probability
that insect pest populations will build up and infest adjacent green-tree stands may be reduced
through removal of vulnerable trees after fire; fuel mass increased on the logged sites as a result
of slash left over from harvest, and on the control site as the result of fire-killed trees falling over.
Dwire, K.A. & Kauffman, J.B. (2003) Fire and riparian ecosystems in landscapes of the western USA. Forest
Ecology and Management, 178, 61-74.
Riparian areas frequently differ from adjacent uplands in vegetative composition and structure,
geomorphology, hydrology, microclimate, and fuel characteristics. These features may contribute
to different fire environments, fire regimes, and fire properties (frequency, severity, behavior,
and extent) in riparian areas relative to uplands. In certain forested riparian areas, fire frequency
has generally been lower, and fire severity has been more moderate than in adjacent uplands,
but in other areas, fires have appeared to burn riparian areas with comparable frequency.
Impacts of land use and management may strongly influence fire properties and regimes in
riparian areas. Fire suppression, livestock grazing, logging, damming and flow regulation,
agricultural diversions, channel modifications, and introduction of invasive species have led to
shifts in plant species composition, structure and distribution of fuel loads, and changes in
microclimate and aerial extent of riparia! n areas. The objectives of this paper are to: (1)
synthesize the limited research conducted on fire regimes in riparian areas relative to uplands;
(2) summarize the distinctive features of riparian zones that influence the properties of fire; (3)
discuss the impacts of land use as they may affect fire behavior in riparian areas; and (4)
describe the adaptations of riparian plant species to fire. Because data are limited on these
topics, portions of the discussion are speculative, and some conclusions are tentative.
Franklin, J.F. & Agee, J.K. (2003) Forging a science-based national forest fire policy. Issues in Science and
Technology, 20, 59-66.
Authors address issues of accumulating fuel loads in North American forests and policy options
for dealing with fuel related problems. They suggest a national forest fire policy that covers every
aspect of fire control, including managing fuels within forests and landscapes, fire suppression,
and salvage and restoration treatments after wildfire.
66
Scientific Basis for Forest Management in the U.S. Inland West
Franklin, J.F., Spies, T.A., Van Pelt, R., Carey, A.B., Thornburgh, D.A., Berg, D.R., Lindenmayer, D.B., Harmon,
M.E., Keeton, W.S., Shaw, D.C., Bible, K., & Chen, J.Q. (2002) Disturbances and structural development of
natural forest ecosystems with silvicultural implications, using Douglas-fir forests as an example. Forest Ecology
and Management, 155, 399-423.
The authors elaborate on existing models for stand structural development using natural stand
development of the Douglas-firówestern hemlock sere in the Pacific Northwest as a primary
example; most of the principles are broadly applicable while some processes (e.g. role of
epicormic branches) are related to specific species. Addresses the use of principles from
disturbance ecology and natural stand development to create silvicultural approaches that are
more aligned with natural processes. Such approaches provide for a greater abundance of
standing dead and down wood and large old trees, perhaps reducing short-term commercial
productivity but ultimately enhancing wildlife habitat, biodiversity, and ecosystem function,
including soil protection and nutrient retention.
Hadfield, J.S. (1988) Integrated pest-management of a western spruce budworm outbreak in the Pacific
Northwest. Northwest Environmental Journal, 4, 301-312.
Haggard, M. & Gaines, W.L. (2001) Effects of stand-replacement fire and salvage logging on a cavity-nesting
bird community in eastern Cascades, Washington. Northwest Science, 75, 387-396.
Authors monitored the response of cavity-nesting species to three snag density treatments
during two breeding seasons 4-5 yr post-fire and logging in Douglas-fir-ponderosa pine forests
in the eastern Cascades, Washington. Snag surveys were used to describe habitat, and both
breeding bird surveys and nest surveys were used to characterize the bird community. Stands
with the medium snag density treatment had the highest abundance, species richness, and
nesting population of cavity nesters. The reasons for this may be: 1) snags were not evenly
distributed within a stand such that both clumped and dispersed snag density habitats were
interspersed in this treatment, and 2) a greater proportion of ponderosa pine snags in medium
density treatments may have attracted species that prefer ponderosa pine for nesting and
foraging. Ponderosa pine was preferred for nest sites and large snags (> 48 cm dbh) provided
nesting habitat for more species than smaller snags. However, smaller sn! ags were used for
nesting and foraging by some species.
Hanson, J.J. & Stuart, J.D. (2005) Vegetation responses to natural and salvage logged fire edges in Douglasfir/hardwood forests. Forest Ecology and Management, 214, 266-278.
Study consisted of nine sites: three salvaged, three unsalvaged, and three old-growth (used as
control). Results suggest that, compared to unsalvaged stands, the removal of snags and
subsequent broadcast burning of salvaged logged stands significantly altered plant composition
and structure of the edge environment. By increasing the patch contrast between burned and
intact forest stands, salvage logging increased the depth of edge influence of fire-created edges
by 15-30 m.
Annotated Bibliography
67
Harmon, M.E., Franklin, J.F., Swanson, F.J., Sollins, P., Gregory, S.V., Lattin, J.D., Anderson, N.H., Cline, S.P.,
Aumen, N.G., Sedell, J.R., Lienkaemper, G.W., Cromack, K., & Cummins, K.W. (1986) Ecology of Coarse
Woody Debris in Temperate Ecosystems. Advances in Ecological Research, 15, 133-302.
Gives a detailed description of woody debris inputs, decomposition, distribution, and ecosystem
importance for plant and animal habitat, terrestrial nutrient cycles, and carbon budgets. The
article also describes human impacts on amounts, dynamics, and functional importance of
coarse woody debris.
Ice, G. & Beschta, R.L. (1999) Should Salvage Logging be Prohibited Following Wildfire? In Proceedings of the
1999 NCASI West Coast Regional Meeting, Vol. II, pp. 451-459. National Council for Air and Stream
Improvement, Inc.
Authors address 5 key statements related to postfire salvage logging: watersheds are damaged
from past practices and can bear no additional impacts from salvage logging following wildfire,
there is no ecological need for immediate intervention on post-fire landscape, allow natural
recovery and recognize the temporal scale involved with ecosystem evolution, salvage logging
should be prohibited in sensitive areas, fire suppression activities should be conducted only
when absolutely necessary.
Johnson, D.W., Murphy, J.F., Susfalk, R.B., Caldwell, T.G., Miller, W.W., Walker, R.F., & Powers, R.F. (2005) The
effects of wildfire, salvage logging, and post-fire N-fixation on the nutrient budgets of a Sierran forest. Forest
Ecology and Management, 220, 155-165.
The effects of fire, post-fire salvage logging, and revegetation on nutrient budgets were estimated
for a site in the eastern Sierra Nevada Mountains that burned in a wildfire in 1981.
Reconstruction of pre-fire nutrient budgets suggested that most C was exported in biomass
during salvage logging and will not be recovered until forest vegetation occupies the site again.
Salvage logging may have resulted in longer-term C sequestration in wood products than would
have occurred had the logs been left in the field to decay, however. Reconstructed budgets
suggested that most N was lost via volatilization during the fire rather than in post-fire salvage
logging (assuming that foliage and O horizons were combusted). Although the study sight is
outside of the Pacific Northwest region, it may provide some useful information regarding the
general behavior of nutrients following fire and salvage logging.
Jurgensen, M.F., Harvey, A.E., Graham, R.T., PageDumroese, D.S., Tonn, J.R., Larsen, M.J., & Jain, T.B. (1997)
Impacts of timber harvesting on soil organic matter, nitrogen, productivity, and health of Inland Northwest
forests. Forest Science, 43, 234-251.
Addresses the importance of soil organic matter to the health and productivity of Inland
Northwest forests. The authors also note the ways in which timber harvesting and site
preperation, wildfires and, prescribed burning often reduce the organic component in soils.
Removal of coarse woody debris through timber harvesting effects soil productivity, and reduced
mycorrhizae development and tree growth often result from soil disturbance.
68
Scientific Basis for Forest Management in the U.S. Inland West
Karr, J.R., Rhodes, J.J., Minshall, G.W., Hauer, F.R., Beschta, R.L., Frissell, C.A., & Perry, D.A. (2004) The Effects
of Postfire Salvage Logging on Aquatic Ecosystems in the American West. BioScience, 54, 1029-1033.
Authors suggest that postfire salvage logging adds another stressor to burned watersheds and
worsens degraded aquatic conditions accumulated from a century of human activity. The
additional damage impedes the recovery and restoration of aquatic systems, lowers water quality,
shrinks the distribution and abundance of native aquatic species, and compromises the flow of
economic benefits to human communities that depend on aquatic resources. Ten
recommendations are made for avoiding damage caused by salvage logging.
Khetmalas, M.B., Egger, K.N., Massicotte, H.B., Tackaberry, L.E., & Clapperton, M.J. (2002) Bacterial diversity
associated with subalpine fir (Abies lasiocarpa) ectomycorrizae following wildfire and salvage-logging in central
British Columbia. Canadian Journal of Microbiology, 48, 611-625.
Ectomycorrhizal fungi have been shown to promote tree growth and establishment in forest
ecosystems by facilitating nutrient and water availability and by increasing protection against root
pathogens. The goal of this paper was to assess the effects of fire and salvage logging on the
diversity of mycorrhizal-bacterial communities. Analysis showed no significant difference in
bacterial diversity between the burned-salvaged and unburned sites.
Larson, A.J. & Franklin, J.F. (2005) Patterns of conifer tree regeneration following an autumn wildfire event in the
western Oregon Cascade Range, USA. Forest Ecology and Management, 218, 25-36.
Investigation of the effects of fire severity and environmental conditions on conifer tree
regeneration 11 years after an autumn wildfire in the western Oregon Cascade Range. Conifer
tree seedlings established promptly and at high densities following fire, in contrast to long
establishment periods documented for many other sites. Coexistence of the three principal
conifer species was more likely on sites that burned with moderate severity. Authors attribute the
rapid initial establishment of Pseudotsuga observed in this study to the persistence of a canopy
seed bankóa biological legacy not normally associated with Pseudotsuga forests. Environmental
factors, fire severity and disturbance timing influence seedling establishment patterns, shaping
future stand composition and development.
Lindenmayer, D.B., Foster, D.R., Franklin, J.F., Hunter, M.L., Noss, R.F., Schmeigelow, F.A., & Perry, D.A. (2004)
Salvage Harvesting Policies After Natural Disturbance. Science, 303, 1303.
A short article outlining the benefits of natural disturbance such as fire and the implications of
postfire logging. Recommends formulating salvage harvesting policies before major
disturbances occur rather than after fire.
McIver, J.D. & Starr, L. (2001) A Literature Review on the Environmental Effects of Postfire Logging. Western
Journal of Applied Forestry, 16, 159-167.
The scientific literature on logging after wildfire is reviewed, with a focus on environmental effects
of logging and removal of large woody structure. Timber harvest methods used by managers can
mitigate erosion effects - for example, logging residue can decrease erosion by impeding
overland flow. Ground disturbance from postfire logging can encourage establishment of
different plant species (including nonnatives) and can influence the growth of trees. The removal
of large woody structures typical in postfire logging operations can change plant species
Annotated Bibliography
69
composition, reduce plant species richness, and increase conifer growth in the first years after
logging, but can also reduce the probability that insect pest populations will build up and infest
adjacent stands. Removal of large woody structure can cause declines in the abundance of
several cavity-nesting bird species.
McIver, J.D.A., P.W., Doyal, J.A., Drews, E.S., Hartsough, B.R., Kellogg, L.D., Niwa, C.G., Ottmar, R.D., Peck, R.,
Taratoot, M., Torgersen, T., & Youngblood, A. (2003) Environmental Effects and Economics of Mechanized
Logging for Fuel Reduction in Northeastern Oregon Mixed-Conifer Stands. Western Journal of Applied Forestry,
18, 238-249.
The authors compare two different mechanized harvest systems in terms of fuel reduction
objectives, economics, and environmental effects. They address three types of environmental
effects: loss of large woody material for wildlife, stand damage, and soil disturbance. This article
may provide information regarding the importance of coarse woody debris in forest ecosystems
and how best to meet objectives of fuel reduction with minimal ecological impacts.
McNabb, D.H. & Swanson, F.J. (1990) Effects of Fire on Soil Erosion. In Natural and Prescribed Fire in Pacific
Northwest Forests (eds J.D. Walstad, S.R. Radosevich & D.V. Sandberg), pp. 315. Oregon State University
Press, Corvallis, OR.
Minshall, G.W. (2003) Responses of stream benthic macroinvertebrates to fire. Forest Ecology and Management,
178, 155-161.
This article provides a synthesis of existing knowledge concerning the responses of benthic
macroinvertebrates to fire as indicators of overall stream ecosystem response, to examine the
implications of these findings for present and proposed forest management practices (e.g.
prescribed burning and salvage logging), and to indicate where additional information is needed.
The author examines the direct and indirect effects of fire on macroinvertebrate communities,
and notes that rapid recovery of macroinvertebrates depends on rapid recovery of riparian
vegetation and flood plains and that anthropogenic activities that may delay this recovery should
be avoided or limited. He notes that virtually all forms of postfire logging can have adverse
effects on stream ecosystems and that the amount of timber removed should not exceed about
25% of merchantable timber.
Morton, D.C., Roessing, M.E., Camp, A.E., & Tyrrell, M.L. (2003) Assessing the Environmental, Social, and
Economic Impacts of Wildfire. GISF Research Paper 001. Yale School of Forestry & Environmental Studies, New
Haven, CT.
National Research Council (2000) Environmental Issues in Pacific Northwest Forest Management National
Academy Press, Washington, DC.
Provides an overview of the region, including demographics and economics; a definition of old
growth and the status and extent of old growth in the region; forest conditions, including forest
health, biodiversity, and wildlife; a chapter on fire and disturbance reviews historical fire regimes,
human alteration of fire regimes, fuels, and postfire logging. The remaining chapters cover
forest products, management, and recommendations.
70
Scientific Basis for Forest Management in the U.S. Inland West
Oregon Society of American Foresters. 2003. Position
http://www.forestry.org/or/position/salvage.php. March 28, 2006.
Statements:
Salvage
Harvesting.
The overall position of the Oregon Society of American Foresters is in support of well planned,
timely, and careful use of salvage harvesting after uncontrollable events have killed or damaged
large numbers of trees in a forest. Potential benefits can include mitigating economic losses,
recovering useful wood products, reducing fire, insect, decay, and safety hazards and creating
desired environmental conditions for successful reforestation. Application of scientific principles
by professional foresters and other resource experts can ensure that economically viable salvage
harvesting will be conducted with proper consideration of environmental and social concerns.
Ottmar, R.D. & Sandberg, D.V. (2001) Wildland fire in eastern Oregon and Washington. Northwest Science, 75,
46-54.
Vegetation succession, disturbance processes, and management practices have resulted in an
increase of fuels and vulnerability to extreme fire behavior and detrimental fire effects. Hazards
of fire are further increased by encroachment of dwellings into forests and rangelands.
Prescribed fire, selective logging, and mechanical fuel treatment are being used to reduce fire
hazard, but there is disagreement as to appropriate balance and efficacy of these actions. New
tools to (1) characterize fuelbeds; (2) predict mesoscale meteorology, fire behavior, fire effects,
smoke production, and dispersal; and (3) demonstrate tradeoffs between prescribed fire and
other fuel treatment methods are continually being improved to assist with wildland fire and
prescribed fire decision making in eastern Oregon and Washington.
Rieman, B., Lee, D., Burns, D., Gresswell, R., Young, M., Stowell, R., Rinne, J., & Howell, P. (2003) Status of
native fishes in the western United States and issues for fire and fuels management. Forest Ecology and
Management, 178, 197-211.
The authors argue that major new efforts to actively manage fires and fuels in forests throughout
the region may be perceived as a threat rather than a benefit to conservation of native fishes and
their habitats. Furthermore, they suggest that management for wildland fire objectives cannot
be isolated from the management of native fishes, or vice versa.
Robichaud, P.R., Beyers, J.L., & Neary, D.G. (2000) Evaluating the Effectiveness of Postfire Rehabilitation
Treatments. Gen. Tech. Rep. RMRS-GTR-63, USDA Forest Service, pp. 85. Rocky Mountain Research Station.
Abstract: Spending on postfire emergency watershed rehabilitation has increased during the
past decade. A west-wide evaluation of USDA Forest Service burned area emergency
rehabilitation (BAER) treatment effectiveness was undertaken as a joint project by USDA Forest
Service Research and National Forest System staffs. This evaluation covers 470 fires and 321
BAER projects, from 1973 through 1998 in USDA Forest Service Regions 1 through 6. A
literature review, interviews with key Regional and Forest BAER specialists, analysis of burned
area reports, and review of Forest and District monitoring reports were used in the evaluation.
The study found that spending on rehabilitation has increased to over $48 million during the past
decade because the perceived threat of debris flows and floods has increased where fires are
closer to the wildland-urban interface. Existing literature on treatment effectiveness is limited,
thus making treatment comparisons difficult. The amount of pr! otection provided by any
treatment is small. Of the available treatments, contour-felled logs show promise as an effective
hillslope treatment because they provide some immediate watershed protection, especially
Annotated Bibliography
71
during the first postfire year. Seeding has a low probability of reducing the first season erosion
because most of the benefits of the seeded grass occurs after the initial damaging runoff events.
To reduce road failures, treatments such as properly spaced rolling dips, water bars, and culvert
reliefs can move water past the road prism. Channel treatments such as straw bale check dams
should be used sparingly because onsite erosion control is more effective than offsite sediment
storage in channels in reducing sedimentation from burned watersheds. From this review, we
recommend increased treatment effectiveness monitoring at the hillslope and sub-catchment scale,
streamlined postfire data collection needs, increased training on evaluation postfire watershed
condi! tions, and development of an easily accessible knowledge base ! of BAER techniques.
Saab, V., Brannon, R., Dudley, J., DOnohoo, L., Vanderzanden, D., Johnson, V., & Lachowski, H. (2002) Selection
of Fire-created Snags at Two Spatial Scales by Cavity-nesting Birds (ed U.F. Service), pp. 835-848.
Authors examined the use of snag stands by seven species of cavity-nesting birds from 19941998. Selection of snags was studied in logged and unlogged burned forests at two spatial
scales: microhabitat (local vegetation characteristics) and landscape (composition and
patterning of surrounding vegetation types). They suggest that salvage prescriptions could be
improved to favor cavity-nesting birds by changing the distribution of snags retained (from
uniform to clumped), even when the same number of snags are harvested.
Schellhaas, R., Camp, A.E., Spurbeck, D., and Keenum, D. (2000) Report to the Colville National Forest on the
results of the South Deep watershed fire history research. USFS Pacific Northwest Research Station, Wenatchee
Forestry Sciences Lab (unpublished).
Sessions, J., Bettinger, P., Buckman, R., Newton, M., & Hamann, J. (2004) Hastening the Return of Complex
Forests Following Fire: The Consequences of Delay. Journal of Forestry, 102, 38-45.
Only a narrow window of opportunity exists to hasten conifer restoration to complex forest
conditions in a cost-effective manner, to reduce risks of insect epidemics and future fires, and
to capture some economic value that could offset restoration costs. Delays in decision making
and implementation will likely destine much of the most intensely burned area to cycles of
shrubs, hardwoods, and recurring fires for many decades.
Sessions, J., Buckman, R., Newton, M., & Hamann, J. (2003). The Biscuit Fire: Management Options for Forest
Regeneration, Fire and Insect Risk Reduction and Timber Salvage. Oregon State University College of Forestry.
In aftermath of several fires in Oregon in 2002, Commissioner requested that OSU College of
Forestry examine post-fire restoration considerations that would be influenced most strongly by
action or inaction as a function of 1-year, 3-year, and 5-year delays in action. The authors
examined forest regeneration, fire and insect risk reduction, and timber salvage and the Biscuit
Fire was used as the study site. The focus of timber salvage evaluations is on costs and time
constraints, soil erosion, and planning (which includes accessibility, harvesting systems,
processing capacity, and a science-based strategy). The authors conclude that salvage logging
will be beneficial and should be carried out rapidly following fire.
72
Scientific Basis for Forest Management in the U.S. Inland West
Stuart, J.D., Grifantini, M.C., & Fox, L. (1993) Early Successional Pathways Following Wildfire and Subsequent
Silvicultural Treatment in Douglas-Fir Hardwood Forests, NW California. Forest Science, 39, 561-572.
Early successional sites were contrasted with old-growth Douglas-fir, hardwood forests to detect
community-level, life form, and species diversity differences due to post wildfire silvicultural
treatments. Treatments included: (1) salvage logged after wildfire; (2) not salvage logged after
wildfire; and (3) previously established plantations. Based on these and results from other
studies, tanoak and other hardwoods inhibited the establishment and growth of Douglas-fir on
salvaged sites, while deerbrush and other shrubs inhibited Douglas-fir on unsalvaged sites.
73
Annotated Bibliography
Annotated Bibliography
Insects and their Management
Amman, G.D., Lessard, G.D., Rasmussen, L.A., & OíNeil, C.G. (1988) Lodgepole Pine Vigor, Regeneration, and
Infestation by Mountain Pine-Beetle Following Partial Cutting on the Shoshone National Forest, Wyoming.
USDA Forest Service Intermountain Research Station Research Paper, 1-8.
The authors sampled different thinning treatments to evaluate the influence on lodgepole pine
vigor. Treatments included the following: 1) removing all trees 7” DBH and above; 2) remove
all trees 10” DBH and above; 3) remove all trees 12” DBH and above; 4) spaced thinnings that
kept about 50 of the best trees; and 5) no cutting (control). The authors found that thinning had
a very beneficial effect: average losses of trees 5” DBH and larger during the 5 years after
thinning ranged from 1% to 7.4% depending on the thinning treatment; this was compared
with 26.5% percent loss in unthinned stands. Remaining trees in thinned stands also showed
better radial growth in the first five years following thinning. The authors suggest that
microclimate of thinned stands may have been influential in reducing beetle numbers.
Amman, G.D. & Logan, J.A. (1998) Silvicultural control of mountain pine beetle: prescriptions and the influence
of microclimate. American Entomologist, 44, 166-177.
The damage caused by mountain pine beetle is described. Control methods for this pest on
ponderosa pine and lodgepole pine are outlined. The effects of stand microclimate on stand
susceptibility to attack by mountain pine beetle are discussed.
Anhold, J.A., Jenkins, M.J., & Long, J.N. (1996) Management of lodgepole pine stand density to reduce
susceptibility to mountain pine beetle attack. Western Journal of Applied Forestry, 11, 50-53.
The authors evaluate density management of young lodgepole pine stands. Descriptions are
given of three relative density zones for lodgepole pine stands that correspond to different levels
of resistance to beetle attack. Two alternative strategies are proposed to reduce future losses
from mountain pine beetle attacks.
Anthony, R.G. & Isaacs, F.B. (1989) Characteristics of Bald Eagle Nest Sites in Oregon. Journal of Wildlife
Management, 53, 148-159.
The authors describe characteristics of Bald Eagle Nest Sites in Oregon, including importance
of stand structure and habitat snags.
Barbour, R.J., Hemstrom, M., Ager, A., & Hayes, J.L. (2005) Effects of spatial scale on the perception and
assessment of risk of natural disturbance in forested ecosystems: Examples from Northeastern Oregon. Forest
Ecology and Management, 211, 210-225.
The authors synthesize five existing analyses to illustrate how spatial and temporal scale affects
the perception of past severity or future risk of natural disturbances such as insect outbreaks.
They present results from the Interior Columbia Basin Ecosystem Management Project
74
Scientific Basis for Forest Management in the U.S. Inland West
(ICBEMP) and the Interior Northwest Landscape Analysis system (INLAS), focusing in
northeastern Oregon, to illustrate the relation of broad-scale policy to the feasibility and impact
of local management.
Bartos, D.L. & Booth, G.D. (1994). Effects of Thinning on Temperature Dynamics and Mountain Pine-Beetle
Activity in a Lodgepole Pine Stand.
This study evaluated the role of stand and bark temperature on mountain pine beetle activity as
a result of thinning lodgepole pine stands in northeast Utah. The authors noted that tree density
is one of the biggest factors in microclimate variation between otherwise similar lodgepole pine
stands. Most of the variation they observed was attributed to two variables: coolest part of the
night and hottest part of the day. The thinned stand was approximately 1-degrees-C warmer
than the unthinned stand. Day temperature was 10 to 11-degrees-C higher than the
corresponding night temperature. The authors suggest that small differences in bark and phloem
temperatures can play a significant role in mountain pine beetle activity: warmer temperatures
on south sides of trees in thinned stands appear to be less hospitable to mountain pine beetles.
Black, S.H. (2005). Logging to Control Insects: The Science and Myths Behind Managing Forest Insect “Pests”:
A synthesis of independently reviewed research. Xerces Society, Portland, OR.
This synthesis report, published by the Xerces Society for Invertebrate Conservation, summarizes
dozens of peer-reviewed articles concerning the management of insect pests in temperate
forests of western North America. The synthesis has three parts: 1) Summary of relevant studies
on the importance of insects to forest function and methods used to control forest “pest” insects;
2) collection of citations of peer-reviewed journal articles and U.S. Forest Service documents
organized by topic area; and 3) compilation of summaries of more than 150 scientific papers
and U.S. Forest Service documents. The author strongly criticizes some current forest
management strategies used in the west, especially thinning after insect outbreak has begun.
He also urges public agencies to reevaluate their current forest management strategies. It
concludes that logging is not the solution to forest insect outbreaks, and in fact could increase
the likelihood of epidemics in some situations.
Borden, J.H. (1993) Uncertain fate of spot infestations of the mountain pine beetle, Dendroctonus ponderosae
Hopkins. Canadian Entomologist, 125, 167-169.
Field studies were conducted in British Columbia to assess the fate of 20 spot infestations of
mountain pine beetle on ponderosa pine. The paper concluded that immediate control of these
spots is essential to prevent the spread of infestations and their ascension to outbreak status.
Brookes, M.H. (1996) Disturbance and forest health in Oregon and Washington. USDA Forest Service - General
Technical Report PNW.
This paper discusses the most significant disturbances and causes of tree mortality or decline
in Oregon and Washington, including interrelations of disturbance with forest management
activities and the effect on native trees. The authors suggest some solutions for reducing the
severity of disturbance, and report on a forest health monitoring pilot project.
Annotated Bibliography
75
Bull, E.L., Aubry, K.B., & Wales, B.C. (2001) Effects of disturbance on forest carnivores of conservation concern
in eastern Oregon and Washington. Northwest Science, 75, 180-184.
This study discusses the effects of forest insects, tree diseases, wildfire and management
strategies designed to improve forest health on forest carnivores of conservation concern in
eastern Oregon and Washington (i.e., Canada lynx, wolverine, fisher, snowshoe hares). The
authors highlight that each species responds differently to wildfire and insect outbreaks,
thinning, stand structure, salvage harvesting and roads.
Bull, E.L. & Carter, B.E. (1996) Tailed frogs: Distribution, ecology, and association with timber harvest in
Northeastern Oregon. USDA Forest Service Pacific Northwest Research Station Research Paper.
Tailed frogs (Ascaphus truei) were found in 42 of 80 streams surveyed in Union, Umatilla,
Wallowa, and Baker Counties in 1992. At least three size classes of larvae were identified in
seven of the streams, thereby suggesting that larvae transform after spending 3 or more years
in the streams. The amount of cobble and fines in the streambed best predicted abundance of
larvae, whereas, cobble, boulders, slope gradient, and stream buffers best predicted abundance
of adults. The authors found no significant difference in number of larvae or adults in streams
with low, moderate or heavy timber harvesting, but they note that forest buffers and stream
characteristics may have exerted a stronger influence on frog survival.
Bull, E.L. & Wales, B.C. (2001a) Effects of disturbance on amphibians of conservation concern in eastern Oregon
and Washington. Northwest Science, 75, 174-179.
This paper discusses effects on eastern Oregon & Washington amphibians of forest insects,
tree diseases, wildfire, and management strategies designed to improve forest health (e.g.,
thinning, prescribed burns, road removal, and spraying with pesticides or biological microbial
agents) are discussed. Species discussed include Oregon spotted frog, Columbia spotted frog,
northern leopard frog, Cascades frog, tailed frog, Larch Mountain salamander, and Cope’s giant
salamander.
Bull, E.L. & Wales, B.C. (2001b) Effects of disturbance on birds of conservation concern in eastern Oregon and
Washington. Northwest Science, 75, 166-173.
This paper discusses the effects on eastern Oregon and Washington birds of forest insects, tree
diseases, wildfire, and management strategies designed to improve forest health (e.g., thinning,
prescribed burns, road removal, and spraying with pesticides or biological microbial agents).
Bird species discussed include bald eagle, peregrine falcon, harlequin duck, upland sandpiper,
northern goshawk, ferruginous hawk, black rosy finch, and seven species of woodpeckers and
nuthatches.
Bunnell, F.L., Squires, K.A., & Houde, I. (2004). Evaluating effects of large-scale salvage logging for mountain
pine beetle on terrestrial and aquatic vertebrates, Rep. No. Working Paper 2004 - 2. Mountain Pine Beetle
Initiative, Canadian Forest Service, Vancouver, B.C.
The authors provide detailed recommendations on integrating large-scale salvage logging after
mountain pine beetle outbreaks, with wildlife and sustainable forest management objectives.
Using natural history data for hundreds of inland northwest wildlife and fish species, they
describe the potential effects of salvage logging on these species or groups of species. They
76
Scientific Basis for Forest Management in the U.S. Inland West
highlight the importance of quantifying effects of salvage logging on forest-dwelling terrestrial
vertebrates, freshwater fish, and non-forest-dwelling vertebrates, and they propose methods for
carrying out these monitoring measures. The authors recommend ways that salvage practices
can be modified to retain potential positive effects, or to reduce negative effects, on vertebrates.
Camp, A. (2002) Damage to residual trees by four mechanized harvest systems operating in small-diameter,
mixed-conifer forests on steep slopes in Northeastern Washington: a case study. Western Journal of Applied
Forestry, 17, 14-22.
This study evaluated the effects of controlled silvicultural treatments on fire-generated,
overstocked, small-diameter stands of timber in the inland West. Harvest units were
commercially thinned using different harvesting technologies, then surveyed for damage. Overall
incidence of wounds, incidence of wounds in different size and severity classes, and wound
locations were compared. In general, cut-to-length processing caused less damage to the
residual stand than whole-tree harvest; skyline yarding was less damaging than forwarder
yarding. The author concludes that appropriate silvicultural prescriptions and harvesting
technologies can reduce wounding to acceptable levels.
Chojnacky, D.C., Bentz, B.J., & Logan, J.A. (2000). Mountain pine beetle attack in ponderosa pine: Comparing
methods for rating susceptibility. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research
Station, Ogden, UT.
Two empirical methods for rating susceptibility of mountain pine beetle attack in ponderosa
pine stands were evaluated. The methods were compared to stand data on bark beetle attacks,
from a survey of 45 sites throughout the Colorado plateau, modeled using a logistic regression
to estimate the probability of attack on individual trees from tree and stand variables. The
authors found that the empirical method developed by Munson and Anhold most closely
correlated to the results they got using the logistic regression. However, this method rated all
45 study sites as either moderately or highly susceptible to bark-beetle attack, which raised
concern among the authors about its lack of sensitivity. The authors suggest that future work
on evaluating risk of bark-beetle impact should consider more than just stand characteristics.
Cochran, P.H. & Barrett, J.W. (1995). Growth and Mortality of Ponderosa Pine Poles Thinned to various Densities
in the Blue Mountains of Oregon. USDA Forest Service Pacific Northwest Research Station Research Paper.
Growth and mortality in a ponderosa pine stand were investigated for 24 years. High mortality
rates from mountain pine beetle occurred on some plots where values for stand density index
exceeded 140. The study concluded that ponderosa pine on low sites should be managed at
low stand densities to avoid problems with mountain pine beetle and to produce large trees in
a reasonable time period. The authors also concluded that long rotations are probably possible
for this species.
Cochran, P.H. & Barrett, J.W. (1998). Thirty-five-year growth of thinned and unthinned ponderosa pine in the
Methow Valley of northern Washington. USDA Forest Service Pacific Northwest Research Station Research
Paper.
Four spacing treatments (9.3, 13.2, 18.7, and 26.4 feet) and control plots (average spacing
4.3 feet) were established in a 47-year-old pine stand. Plots were measured at 5-year intervals.
Results showed that self-thinning did not occur in the unthinned plots, although there was some
Annotated Bibliography
77
suppression-caused mortality. A shift from suppression-caused mortality to insect-caused
mortality took place when QMDs reached 7 inches. The authors conclude that density
management is necessary to produce reasonable growth rates of even the largest trees in the
stand and to speed the development of mid-seral conditions. A management strategy using
precommercial thinning to produce 20-inch trees early with repeated commercial thinnings over
long rotations to produce much larger trees seems reasonable. Some potential cubic-volume
production will be lost by using this strategy, but the social and monetary values associated with
large trees will be increased, and the probability of severe mortal! ity to pine beetles will be
greatly reduced.
Cochran, P.H. & Barrett, J.W. (1999). Thirty-five-year growth of ponderosa pine saplings in response to thinning
and understory removal. USDA Forest Service Pacific Northwest Research Station Research Paper.
This study evaluated effects of different spacing and thinning treatments on diameter increments
and stand basal area increments. Average height growth of all trees increased linearly, and stand
cubic volume growth decreased linearly as spacing increased. Large differences in tree sizes
developed over the 35 years of study with various spacing treatments. Plots without understory
grew more during the first 20 years of study but soil quality decreased. During the last 15 years,
growth rates on plots without understory were not superior to plots with understory when
adjusted to common basal areas and volumes. Growth rates for the largest trees on the plots
were decreased by competition from smaller trees. After 35 years, total cubic volume yield
decreased linearly as spacing increased but Scribner board-foot yields increased curvilinearly
as spacing increased, and spacings of 13.2, 18.7, and 26.4 feet produced about the same
board-foot yield. Live crown ratios increased with increasing spacing, primarily because of
increased height growth. The study recommended that spacing for precommercial thinnings
on similar sites should be at least 14 feet and much higher spacings could be warranted if
managers wish to grow stands of large-diameter trees with low mortality from bark beetles.
Cochran, P.H. & Dahms, W.G. (2000). Growth of lodgepole pine thinned to various densities on two sites with
differing productivities in central Oregon. USDA Forest Service Pacific Northwest Research Station Research
Paper.
This study evaluated the effect of different thinning densities on two natural lodgepole pine
stands in central Oregon with differing productivities. Low incidence of mortality caused by
mountain pine beetle occurred at a stand density index below 170 for both sites. Net total cubicvolume yield was higher for the three highest growing stock levels than net yields for unmanaged
stands from yield tables at comparable sites and ages. Ponderosa pine outgrew lodgepole pine
for the range of stand ages on the highly productive site where the growth of both species was
examined (33 to 58 years). The authors concluded that early spacing control coupled with later
commercial thinnings to keep stand densities between SDI 114 and SDI 170 should reduce
mortality considerably, allow most of the wood produced to be captured by merchantable trees,
and greatly increase quadratic mean diameters and live crown ratios over unmanaged stands
at the same age. These stands would be more pleasing visually, and their rotation ages may be
longer.
78
Scientific Basis for Forest Management in the U.S. Inland West
Cole, D.M. & Koch, P. (1995). Managing lodgepole pine to yield merchantable thinning products and attain
sawtimber rotations. USDA Forest Service Intermountain Research Station.
This paper suggests solutions for managing lodgepole pine stands to reach an 80-year
sawtimber rotation age and merchantable thinning products, despite serious hazard from bark
beetles and wildfire. The authors suggest that thinning at 30 years of age is central to achieving
the recommended alternative management regimes. Management regimes that provide
attainable rotations are presented in summary tables, by three site index classes and a number
of initial stand density classes.
Daterman, G.E., Wenz, J.M., & Sheehan, K.A. (2004) Early Warning System for Douglas-fir tussock moth
outbreaks in the western United States. Western Journal of Applied Forestry, 19, 232-241.
The authors describe the use of the Early Warning System pheromone-based trapping system
used to detect outbreaks of Douglas-fir tussock moth (Orgyia pseudotsugata) in the western
United States. The System focuses attention on the relatively limited areas where outbreaks
may be developing. During 20+ years of monitoring, the Early Warning System provided
warnings of 1-3 years for seven of nine outbreaks. The authors recommend that plots should
be evenly distributed over host-type forests at a density of at least one Early Warning System plot
per 3,000 ac. They also emphasize that after potential outbreaks have been identified by the
Early Warning System, ground sampling for egg masses and larvae is necessary to characterize
local DFTM populations.
DellaSala, D.A., Olson, D.M., Barth, S.E., Crane, S.L., & Primm, S.A. (1995) Forest health: moving beyond rhetoric
to restore healthy landscapes in the inland Northwest. Wildlife Society Bulletin, 23, 346-356.
The authors urge a more science-based approach to forest and landscape health in the inland
northwest.
Dodds, K.J., Ross, D.W., Randall, C., & Daterman, G.E. (2004) Landscape level validation of a Douglas-fir beetle stand
hazard-rating system using geographical information systems. Western Journal of Applied Forestry, 19, 77-81.
The authors used GIS technology and historical infestation data to validate a Douglas-fir beetle
hazard-rating system currently used by the USFS in the Western U.S. This hazard-rating system
is based on stand characteristics including percent Douglas-fir basal area (BA), stand BA,
average Douglas-fir dbh, and stand age. To validate the hazard-rating system, stand information
and aerial detection survey maps from 1996-1999 were combined in a GIS. Analyses
determined that the highest amount of acreage infested and highest tree mortality occurred in
moderate- and high-hazard stands, although the total area of these stands was less than that
in other hazard classes. As beetle populations shifted from endemic to epidemic population
levels, more acres were infested and tree mortality was greater in high-hazard areas. The use
of GIS and aerial detection survey maps provided a novel alternative for validating a forest insect
hazard-rating system.
Dwyer, G., Dushoff, J., & Yee, S.H. (2004) The combined effects of pathogens and predators on insect outbreaks.
Nature, 430, 341-345.
The authors attempt to demonstrate that insect outbreaks can be explained by a model that
includes both a generalist predator and a specialist pathogen. In this host pathogen-predator
Annotated Bibliography
79
model, stochasticity causes defoliator densities to fluctuate erratically between an equilibrium
maintained by the predator, and cycles driven by the pathogen. Outbreaks in this model occur
at long but irregular intervals, matching the data. Results suggest that explanations of insect
outbreaks must go beyond classical models to consider interactions among multiple species.
Dymond, C.C., Wulder, M.A., Shore, T.L., Nelson, T., Boots, B., & Riel, B.G. (2006) Evaluation of risk assessment
of mountain pine beetle infestations. Western Journal of Applied Forestry, 21, 5-13.
This study evaluated an established risk rating system for mountain pine beetles in one area of
British Columbia. Global positioning systems were used to survey an infestation. The annual
data was used to generate risk for a given year and to compare the ratings with survey data
from the subsequent year. The authors found that the risk rating system accurately predicted
risk in stands that were infested, but not all high risk stands were subsequently attacked. The
study highlights the difficulty of modeling processes that have a stochastic component, but the
authors recommend that estimating risk on an annual basis is sufficiently reliable using this tool
to aid in the strategic planning of forest managers.
Elkin, C.M. & Reid, M.L. (2004) Attack and reproductive success of mountain pine beetles (Coleoptera:
Scolytidae) in fire-damaged lodgepole pines. Environmental Entomology, 33, 1070-1080.
This study evaluated whether mountain pine beetles preferentially attack lodgepole trees that
have been damaged by fire, and how fire damage affects beetles’ reproductive success.
Different intensities of ground fires were simulated by artificially burning a strip of bark that
extended zero-thirds, one-third, two-thirds or three-thirds around a tree’s circumference. These
treatments were applied ~7 weeks before beetles emerged from surrounding trees. The study
found that beetles did not preferentially attack fire-damaged trees, and that fire damage had no
effect on the number of beetles landing on a tree, which trees were attacked, attack rate, attack
density or the body size of beetles attacking a tree. Beetle reproductive success also was not
affected by fire damage. Beetles were more likely to overcome tree defenses and produce
successful egg galleries on fire-damaged trees than on undamaged trees, but this was only
observed on trees with low beetle attack densities. I! f beetle attack density was high, trees were
successfully attacked irrespective of burn treatment. Results suggest that fire damage only
affects mountain pine beetle reproduction and population growth in areas where attack densities
are low. In other situations, fire damage will have negligible effects on beetle attack and
reproductive success.
Eng, M. (2004). Forest stewardship in the context of large-scale salvage operations: an interpretation paper, Rep.
No. Tech. Rep. 019. B.C. Min. For., Res. Br., Victoria, B.C.
This report was prepared for the British Columbia Ministry of Forestry to inform their Allowable
Annual Cut determinations for Lakes, Prince George, and Quesnel Timber Supply areas in British
Columbia due to extensive mountain pine beetle outbreaks. The author argues that it is neither
desirable nor possible to harvest all of the affected pine forests. He provides multiple
recommendations regarding the conservation of stewardship values (including riparian
management areas, wildlife trees and habitat areas, coarse woody debris, and others) during
large-scale salvage operations. Other related recommendations are made about access
structures, adverse effects on peak flows and soil erosion, and silviculture that might lessen
future problems with mountain pine beetle outbreaks, fire risk at the wildland-urban interface,
and monitoring programs.
80
Scientific Basis for Forest Management in the U.S. Inland West
Fayt, P., Machmer, M.M., & Steeger, C. (2005) Regulation of spruce bark beetles by woodpeckers - a literature
review. Forest Ecology and Management, 206, 1-14.
Relative to host suitability and invertebrate predators and parasitoids, predation by vertebrates
generally has been assigned a trivial role in the dynamics of conifer bark beetle populations
(Coleoptera, Scolytidae). Here, the authors review quantitative studies that address the trophic
relationship between bark beetles infesting spruce (Picea spp.) and woodpeckers. The authors
conclude that, despite a paucity of landscape-level data, circumstantial evidence documents a
stabilizing role of woodpeckers on the population dynamics of their prey.
Ferguson, D.E. & Carlson, C.E. (1993). Predicting Regeneration Establishment with the Prognosis Model.
The authors describe version 2 of the Regeneration Establishment Model, a submodel of the
Prognosis Model, which predicts various regeneration parameters of 10 conifer species following
timber harvests in Montana, central Idaho and northern Idaho. The model includes the
influence of western spruce budworm on regeneration success. The model predicts the
probability of stocking, seedling density, species composition, and seedling heights 2 to 20 years
after harvest.
Filip, G.M. (1994) Forest Health Decline in Central Oregon - a 13-Year Case-Study. Northwest Science, 68, 233-240.
A 200-ha mixed-conifer forest in central Oregon was examined in 1979 and 1992 to document
causes of forest health decline. The authors found particular fluctuations in grand fir, which
increased significantly in stems/ha but also experienced the greatest mortality, due to root
pathogens, Armillaria ostoyae (Romagn.) Herink, the fir engraver (Scolytus ventralis LeConte),
and western spruce budworm (Choristoneura occidentalis Freeman). The authors concluded
that a complex of pest species in this forest would likely reduce fir abundance, and that surviving
trees would benefit from the pest-altered tree biomass recycled as nutrients if catastrophic
wildfires do not occur first. They predict that forest health will continue to decline as grand fir
and other fir species increase. The authors suggest that traditional silviculture and its new
modifications can improve forest health if pest populations are recognized and less susceptible
tree species are increased.
Filip, G.M., Colbert, J.J., Shaw, C.G., Hessburg, P.F., & Hosman, K.P. (1993) Influence of Dwarf Mistletoe and
Western Spruce Budworm on Growth and Mortality of Douglas-Fir in Unmanaged Stands. Forest Science, 39,
465-477.
This study examined permanent inventory plots in 94 unmanaged stands of primarily Douglasfir on three national forests in Oregon and Washington for growth suppression caused by dwarf
mistletoe and western spruce budworm over a 10-year period. Dwarf mistletoe significantly
decreased 10-yr diameter increment. Western spruce budworm significantly reduced diameter
increment and basal area increment. No significant interactions between defoliation and dwarf
mistletoe were found. Mortality was highest in stands with the most dwarf mistletoe and in
stands with the most severe defoliation. There were no significant differences in diameters of
dead trees among severity classes for dwarf mistletoe.
Annotated Bibliography
81
Filip, G.M., Ganio, L.M., Oester, P.T., Mason, R.R., & Wickman, B.E. (2002) Ten-year effect of fertilization on tree
growth and mortality associated with Armillaria root disease, fir engravers, dwarf mistletoe, and western spruce
budworm in northeastern Oregon. Western Journal of Applied Forestry, 17, 122-128.
In October 1988, randomly selected plots in a mixed-conifer forest in northeastern Oregon
received fertilizer treatment with nitrogen, potassium or phosphorus by helicopter: Ten years
after treatment, grand fir mortality within plots averaged 37% (range 4 to 56%) of the sampled
trees. Fir mortality was associated with fir engraver beetles, flatheaded fir borers, Armillaria root
disease, and defoliation by western spruce budworm. After 10 yr, there were no significant
fertilizer effects on grand fir and western, larch with respect to (1) incidence of mortality; (2)
diameter increment; (3) vigor as assessed by cambial electrical resistance (CER); (4) live crown
ratio; and (5) larch dwarf mistletoe severity rating (DMR). Possible reasons why fertilization in
this experiment did not have the same effects as fertilization in smaller studies are discussed.
Filip, G.M., Wickman, B.E., Mason, R.R., Parks, C.A., & Hosman, K.P. (1992) Thinning and Nitrogen-Fertilization
in a Grand Fir Stand Infested with Western Spruce Budworm .3. Tree Wound Dynamics. Forest Science, 38,
265-274.
Part three of four-part study testing the effects of thinning and nitrogen fertilization in grand fir
stands in Oregon that had been defoliated by western spruce budworm. Specifically this part
of the study evaluated effects on stem-wound closure and associated wood decay. After 3 years,
thinning or fertilizing significantly improved tree diameter growth, and fertilizing significantly
improved tree vigor. Results support the use of thinning and fertilization to improve grand fir
growth and vigor and reduced losses from wound-associated stem decay.
Furniss, R.L. and Carolin, V.M. 1977. Western forest insects. U.S.D.A. Forest Service. Misc. Publ. 1339, Wash.
D.C., 654.
Goyer, R.A., Wagner, M.R., & Schowalter, T.D. (1998) Current and proposed technologies for bark beetle
management. Journal of Forestry, 96, 29-33.
The authors review behavioral chemicals that disrupt mating and host tree selection, thereby
reducing losses to bark beetles. In the Pacific Northwest, thinning and selection of appropriate
species have been the preferred management options, but pheromones-both attractants and
antiaggregants-show promise. The authors also note that Ips species prefer slash, so thinning
operations that leave a lot of slash can actually increase likelihood of attack by these species.
Han, H.S. & Renzie, C. (2005) Productivity and cost of partial harvesting method to control mountain pine beetle
infestations in British Columbia. Western Journal of Applied Forestry, 20, 128-133.
This article addresses the operational challenges and costs of “Snip and Skid” logging in central
British Columbia, where small patch cutting (< 1 ha in size) in mature lodgepole pine stands is
used to slow the spread of mountain pine beetle. Smaller trees increase costs. Planning and
layout, ground probing, and baiting, further increase the total cost of implementation. In this
study, five trees were damaged per 100 in along the skid trails created to access the patches.
The authors found no high stumps or significant impacts on soils.
82
Scientific Basis for Forest Management in the U.S. Inland West
Hartsough, B.R., Zhang, X.S., & Fight, R.D. (2001) Harvesting cost model for small trees in natural stands in the
Interior Northwest. Forest Products Journal, 51, 54-61.
Realistic logging cost models are needed for long-term forest management planning. Data from
numerous published studies were combined to estimate the costs of harvesting small trees in
natural stands in the Interior Northwest of North America. Six harvesting systems were modeled.
Four address gentle terrain: manual log-length, manual whole-tree, mechanized whole-tree,
and mechanized cut-to-length systems. Two cable systems were included for steeper terrain:
manual log-length and mechanized cut-to-length systems. A stand-alone program incorporating
all the relationships is available.
Hayes, J.L., Ager, A.A., Barbour, R.J., & Eds.), T. (2004). Methods for Integrated Modeling of Landscape Change:
Interior Northwest Landscape Analysis System. U.S. Department of Agriculture, Forest Service, Pacific
Northwest Research Station, Portland, Oregon.
The Interior Northwest Landscape Analysis System (INLAS) links a number of resource,
disturbance, and landscape simulations models to examine the interactions of vegetative
succession, management, and disturbance with policy goals. The effects of natural disturbance
like wildfire, herbivory, forest insects and diseases, as well as specific management actions are
included. Chapter 8 specifically focuses on simulating mortality from forest insects and diseases.
This Chapter describes methods for incorporating the effects of insects and diseases on
coniferous forests into forest simulation models and discuss options for including this capability
in the modeling work of the Interior Northwest Landscape Analysis System (INLAS) project. The
authors discuss options for modeling insect and disease mortality within the INLAS project.
Hayes, J.L. & Daterman, G.E. (2001) Bark beetles (Scolytidae) in eastern Oregon and Washington. Northwest
Science, 75, 21-30.
This paper summarizes life history and general ecology of six beetle species of concern in
eastern Oregon and Washington: Douglas-fir beetle, mountain pine beetle, western pine beetle,
spruce beetle, fir engraver, and pine engraver. The authors describe ways that these beetles
interact with wildfire, windstorms, disease, other insects, and land management practices. The
authors emphasize that at low population levels, beetles perform useful ecological functions, but
outbreaks can cause extensive tree mortality and increase risk of wildfire. Natural and
semiochemical-baited traps, pesticides and anti-aggregants are discussed. Stand susceptibility,
hazard, or risk-rating systems exist for most of these species, and infestation growth or damage
models are available for a few. The authors note that that salvage of infested, wind- or firedamaged trees can prevent population build-ups if done promptly, and that these methods can
be integrated with prescribed fire and tree thinn! ing. The authors discuss the use of decisionsupport tools for the species.
Hayes, J.L. & Ragenovich, I. (2001) Non-native invasive forest insects of eastern Oregon and Washington.
Northwest Science, 75, 77-84.
The authors discuss the increased potential for invasion by non-native insect species in forests
east of the Cascade crest. They note that if forests lack natural control mechanisms, non-native
species may become established, spread, and inflict substantial ecological and economic
damage. The authors suggest that maintaining forest health can reduce the risk of widespread
insect outbreaks for indigenous species, and can mitigate the effect of non-native species;
Annotated Bibliography
83
however, they also emphasize that the most effective management options focus on prevention
and suppression. The authors discuss recent east-side invaders such as larch casebearer, gypsy
moth (both Asian and European strains), and the balsam woolly adelgid. The authors also
describe an increasing number of introduced woodboring insects that have been discovered in
Oregon and Washington that are of growing concern.
Hemstrom, M.A. (2001) Vegetative patterns, disturbances, and forest health in eastern Oregon and Washington.
Northwest Science, 75, 91-109.
This paper focuses on relations between vegetation pattern, disturbance, and forest health and
productivity. The authors note that at all scales, vulnerability to disturbance appears to increase
when vegetation condition and pattern differs from the historical or expected range for a given
environment. Generally, forests that are older, composed of larger trees, denser, more
homogeneous, or more contiguous than would be expected under natural or historical
disturbance regimes are more vulnerable to mortality from insects and disease. Factors related
to vulnerability include site potential, host abundance, canopy structure, host size, patch vigor,
patch density, patch connectivity, topography, and logging disturbance. Mortality from insects
and disease contributes to diverse habitat, but current levels of tree mortality from insects and
disease are often outside the historical or expected range given site environment. The authors
note that high levels of mortality may continue because many forests have become more
homogeneous, contiguous, and dominated by shade-tolerant species owing to fire suppression
and management.
Hemstrom, M.A., Korol, J.J., & Hann, W.J. (2001) Trends in terrestrial plant communities and landscape health
indicate the effects of alternative management strategies in the interior Columbia River basin. Forest Ecology
and Management, 153, 105-126.
Current and potential future conditions of terrestrial plant communities and landscape health
were modeled for three alternative public land management strategies in the interior Columbia
River basin. Landscape health was defined as an integration of the degree to which vegetation
and disturbance conditions resemble native patterns and support levels of human activity.
Departure from the “historical” regime in wildland environments was found to be related to
altered disturbance patterns, especially changed fire regimes, forest insect and disease levels
and excessive livestock grazing effects. Overall, mid-seral forests are currently more prevalent
than they were in the past and old forests, especially single-layer structural types, are less
abundant. The authors conclude that proposed management strategies that emphasize
maintenance and restoration activities in a hierarchical landscape approach should generate
improved landscape health conditions over the next 100 years, but the massive changes to
disturbance and vegetation patterns from historical to current times and the cost of
implementing restoration activities make dramatic improvement unlikely.
Hessburg, P.F. & Agee, J.K. (2003) An environmental narrative of Inland Northwest United States forests, 18002000. Forest Ecology and Management, 178, 23-59.
The authors discuss fire and other rangeland disturbance processes in the Inland Northwest over
the past 200 years. They describe the ways that two centuries of settlement, exploitation,
management, and climate variation have transformed the fire regimes, vegetation and fuel
patterns, and overall functionality of inland northwest forests. They highlight key changes to
forest landscape patterns and processes that occurred under these combined influences,
84
Scientific Basis for Forest Management in the U.S. Inland West
discuss implications of the changes, and progress towards restoring sustainability. They discuss
current issues and future options associated with ecosystem management, including the low
likelihood of social consensus concerning desired outcomes, the lack of integrated planning,
analysis, and decision support tools, and mismatches between existing land management
planning processes, Congressional appropriations, and complex management and restoration
problems.
Hessburg, P.F., Smith, B.G., Salter, R.B., Ottmar, R.D., & Alvarado, E. (2000) Recent changes (1930s-1990s) in
spatial patterns of interior northwest forests, USA. Forest Ecology and Management, 136, 53-83.
The authors characterized recent historical and current vegetation composition and structure
within the interior Columbia River basin and portions of the Klamath and Great Basins. For many
subwatersheds, they constructed historical and current vegetation maps from 1932 to 1966
and 1981 to 1993 aerial photos, and classified cover types, structural classes, and potential
vegetation types. They characterized change in vegetation spatial patterns using a suite of class
and landscape metrics and a spatial pattern analysis program, then translated change in
vegetation patterns to change in patterns of vulnerability to wildfires, smoke production, and 21
major forest pathogen and insect disturbances. They found that shifts from early to late seral
conifer species were evident in many forests. Many forests are now dominated by shade-tolerant
conifers, and exhibit elevated fuel loads and severe fire behavior attributes indicating expanded
future roles of certain defoliators, bark! beetles, root diseases, and stand replacement fires.
The authors suggest that an improved understanding of change in vegetation spatial patterns,
causative factors, and links with disturbance processes will assist managers and policymakers
in making informed decisions about how to address important ecosystem health issues.
Hindmarch, T.D. & Reid, M.L. (2001) Thinning of mature lodgepole pine stands increases scolytid bark beetle
abundance and diversity. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere,
31, 1502-1512.
This study evaluated the effectiveness of thinning as a management tool for bark beetles in
Alberta, Canada. The authors sampled abundance and diversity of secondary bark beetles in
mature thinned and unthinned lodgepole pine stands. They found that breeding habitat for
secondary bark beetles (fresh coarse woody debris) was much more abundant in thinned stands
than in unthinned stands in the first year after thinning, but then returned to background levels.
Temperature and wind speeds were higher in thinned stands in all 3 years after thinning. The
abundance of striped ambrosia beetles and pine engravers captured in baited funnel traps and
window traps remained significantly higher in thinned stands than in unthinned stands in all 3
years after thinning, while the diversity of bark beetles remained constant or increased over this
period. The authors concluded that the persistent changes in microclimate following thinning,
especially increased wind, were partly responsible ! for thinned stands having more secondary
bark beetles than unthinned stands.
Howell, P.J. (2001) Effects of disturbance and management of forest health on fish and fish habitat in eastern
Oregon and Washington. Northwest Science, 75, 157-165.
This paper discusses effects of fire, forest insects and diseases, grazing, and forest health
treatments on fish populations and habitat. Fire, insects, and disease affect fish habitat by their
influence on the rate and volume of woody debris recruitment to streams, canopy cover and
water temperature, stream flow, channel erosion, sedimentation, nutrients, and residual
Annotated Bibliography
85
vegetation. The authors also discuss the use of more benign techniques (e.g., lower-impact
logging systems) and pulsed treatments consistent with characteristics of natural disturbance
regimes for achieving both terrestrial and aquatic objectives.
Huggard, D.J., Klenner, W., & Vyse, A. (1999) Windthrow following four harvest treatments in an Engelmann
spruce/subalpine fir forest in southern interior British Columbia, Canada. Canadian Journal of Forest ResearchRevue Canadienne De Recherche Forestiere, 29, 1547-1556.
The authors measured the effects of different logging treatments on windthrow: 10-ha clearcuts,
arrays of 1-ha patch cuts, arrays of 0.1-ha patch cuts, individual-tree selection cuts, and uncut
controls. They also examined edge effects and conditions predisposing trees to windthrow.
Windthrow of Engelmann spruce in the 2.7 years following harvesting increased slightly in
harvested treatments, with highest rates in individual tree selection units and lowest rates in
0.1-ha patch-cut arrays. Windthrow was concentrated near north and east edges of 1-ha and
10-ha openings but was dispersed throughout the more uniform treatments. Windthrown trees
did not differ from random trees in diameter but had lower height/diameter ratios, probably
reflecting the greater windthrow observed in subxeric sites on complex, elevated topography. The
rates and distribution of windthrow in different harvest treatments have implications for
ecological processes, salvage, long-term windthrow potential, and mitigation possibilities.
Hughes, J. & Drever, R. (2001). Salvaging Solutions: Science-based management of BC’s pine beetle outbreak.
David Suzuki Foundation, Forest Watch of British Columbia and Canadian Parks and Wilderness Society (BC
Chapter).
This report includes science-based recommendations for managing mountain pine beetle
outbreaks in British Columbia
Hummel, S. & Agee, J.K. (2003) Western spruce budworm defoliation effects on forest structure and potential
fire behavior. Northwest Science, 77, 159-169.
The authors evaluated forest composition and structure between 1992 and 2000 in a late
successional reserve on the eastern slope of the Cascade Mountains that had been influenced
by decades of fire exclusion. They found that multi-layered canopies and high numbers of
shade-tolerant true fir trees had interacted with western spruce budworm to alter forest structure
and to affect potential fire behavior and effects. Canopy closure decreased significantly and
coarse woody debris load increased significantly during the period. Tree mortality was mostly in
the smaller (<20 cm) diameter classes. Potential surface fire flame lengths increased
significantly from 1.4 inches in 1992 to 1.9 m in 2000, but changes in torching potential and
independent crown fire behavior were not significant. The authors predicted that a wildfire in
conditions similar to those in 2000 would not be of stand replacement severity.
Johnstone, W.D. (2002). Thinning lodgepole pine in Southeastern British Columbia: 46-year results. Victoria,
Canada: Ministry of Forests, British Columbia.
This study reported the effects of thinning 53-year-old, fire-origin lodgepole pine, 46 years after
treatment. Five thinning treatments plus unthinned controls were established in plots in the
Montane Spruce biogeoclimatic zone in southeastern British Columbia. The authors concluded
that on an area basis, the response to thinning can be substantial, particularly when the net
periodic annual increment of the thinned plots is compared to that of the unthinned controls.
86
Scientific Basis for Forest Management in the U.S. Inland West
During the 46-year observation period, the plots were attacked by mountain pine beetle, and
results of the study support the theory that heavy thinning may help to beetle-proof lodgepole
pine stands.
Jurgensen, M.F., Harvey, A.E., Graham, R.T., Page-Dumroese, D.S., Tonn, J.R., Larsen, M.J., & Jain, T.B. (1997)
Impacts of timber harvesting on soil organic matter, nitrogen, productivity, and health of Inland Northwest
forests. Forest Science, 43, 234-251.
This paper discusses the importance of soil organic components to the health and productivity
of Inland Northwest forests. The authors describe the effects of timber harvesting, extensive
site preparation, wildfires and severe prescribed burns on surface organic material over large
areas. Organic matter reductions can have important implications for soil chemical, biological
and physical properties. Maintaining adequate amounts of organic matter on some forest sites
in the Inland Northwest may temporarily increase the risk of wildfire or favor the activity of certain
insects or disease fungi. However, carefully planned prescribed burns and mechanical site
preparation can be practiced on most sites with relatively low impacts on soil organic levels,
while accomplishing fuel reduction, seedbed preparation, and reductions in competing
vegetation. The authors conclude that the maintenance of adequate soil organic matter levels
is critical for sustaining forest health and productivity under the variable moisture and
temperature conditions of this region.
Lehmkuhl, J.F., Hessburg, P.F., Everett, R.L., Huff, M.H., & Ottmar, R.D. (1994) Eastside forest ecosystem health
assessment. Volume III: assessment. Historical and current forest landscapes of eastern Oregon and
Washington. Part I: vegetation pattern and insect and disease hazards. General Technical Report - US
Department of Agriculture, Forest Service.
This study analyzed historical and current vegetation composition and structure in 49 sample
watersheds, primarily on National forests, within six river basins in E Oregon and Washington,
describing vegetation attributes, landscape patterns, the range of historical variability, scales of
change, and disturbance hazards. Insect and disease hazards changed little, usually <10%, at
the river basin scale because there was considerable variation at the watershed scale, where
large changes in hazards were common.
Lehmkuhl, J.F., Kie, J.G., Bender, L.C., Servheen, G., & Nyberg, H. (2001) Evaluating the effects of ecosystem
management alternatives on elk, mule deer, and white-tailed deer in the interior Columbia River basin, USA.
Forest Ecology and Management, 153, 89-104.
Elk (Cervus elaphus), mule deer (Odocoileus hemionus), and white-tailed deer (Odocoileus
virginianus) are highly valued for their game, aesthetic, and spiritual qualities by sportsman,
wildlife enthusiasts, and Native Americans in North America. As part of the Interior Columbia
Basin Ecosystem Management Project (ICBEMP) of the US Forest Service and Bureau of Land
Management, the authors (1) defined key habitat associations of those species and (2)
determined how three ecosystem management alternatives of a supplemental draft
environmental impact statement (SDEIS) might affect the regional distribution of habitat for
those species across the Basin over the next 100 years. Forage habitat capability was a function
of the percentage area of rangeland and early seral forest community types, and the qualitative
influences of livestock overgrazing, wildfire, and prescribed fire. Under all management
alternatives, habitat capability increased about 5% for all three ungulate species over the next
100 years. Limitations of the coarse analysis scale restrict application of the model to large-
Annotated Bibliography
87
scale assessments. Lacking regional population data, verification of model output was not
feasible at the scale of analysis. However, the model was considered useful for tracking regional
changes given the available habitat data and regional-scale objectives of the effort.
Li, C., Barclay, H.J., Hawkes, B.C., & Taylor, S.W. (2005) Lodgepole pine forest age class dynamics and
susceptibility to mountain pine beetle attack. Ecological Complexity, 2, 232-239.
The authors highlight the importance of fire history within a forest landscape to evaluating stand
susceptibility to mountain pine beetle. They describe the importance of understanding forest
age class dynamics, given that mountain pine beetles attack mature pine stands. They used a
model simulation to estimate how the proportion of susceptible area could be influenced by
different fire regimes. The results of the simulation suggest that the temporal dynamics of the
area susceptible to mountain pine beetle attack are complex and depend on the fire history of
the study area, if the area is experiencing large and irregular stand-replacement fires. The
authors conclude that age range of the lodgepole pine forest stands susceptible to mountain pine
beetle attack might significantly affect the estimate of the area susceptible to attack.
Lindenmayer, D.B., Foster, D.R., Franklin, J.F., Hunter, M.L., Noss, R.F., Schmiegelow, F.A., & Perry, D. (2004)
Ecology - Salvage harvesting policies after natural disturbance. Science, 303, 1303-1303.
The authors discuss issues related to salvage harvesting after natural disturbance in forests
around the world. They describe the widely differing opinions related to human actions before,
during and after such salvage harvesting. They emphasize the need to consider natural
disturbance regimes in forest systems, and how in many cases such disturbances are essential
to maintaining forest biodiversity and productivity. They note that some species might not be
able to adapt to two major disturbances in rapid succession, namely tree mortality from insect
outbreak followed by extensive salvage logging.
Logan, J.A. & Powell, J.A. (2001) Ghost forests, global warming, and the mountain pine beetle (Coleoptera:
Scolytidae). American Entomologist, 47, 160-172.
The authors describe the nature and extent of mountain pine beetle outbreaks, and utilize a
model to evaluate the potential responses of the beetle to climate changes in high elevation
pine systems. The authors focus on timing and synchrony of outbreaks, and how these might
change with changing climate.
Mason, R.R. & Paul, H.G. (1999) Long-term dynamics of lodgepole needle miner populations in central Oregon.
Forest Science, 45, 15-25.
This article describes population dynamics of lodgepole needle miner populations in Central Oregon.
Mason, R.R. & Wickman, B.E. (1991) Integrated Pest-Management of the Douglas-Fir Tussock Moth. Forest
Ecology and Management, 39, 119-130.
This paper describes how population densities of the Douglas-fir tussock moth fluctuate over
time and with different climatic conditions. Fluctuations in density on warm, dry sites where
populations have a high intrinsic rate of increase are more likely to periodically reach outbreak
numbers than where rates of increase are relatively small. The paper describes current methods
to monitor population and to predict trends, and control methods including environmentally
88
Scientific Basis for Forest Management in the U.S. Inland West
safe chemical and microbial insecticides. Computer models are discussed that predict growth
loss, tree mortality, and top-kill during outbreaks are available as aids to making management
decisions. The authors suggest that silvicultural practices favoring seral nonhost species on
high-risk sites may be the best prescription for reducing the impact of tussock moth outbreaks.
Mason, R.R., Wickman, B.E., Beckwith, R.C., & Paul, H.G. (1992) Thinning and Nitrogen-Fertilization in a Grand
Fir Stand Infested with Western Spruce Budworm .1. Insect Response. Forest Science, 38, 235-251.
This paper summarizes part one of four-part study testing the effects of thinning and nitrogen
fertilization in grand fir stands in Oregon, as possible alternative techniques for managing
outbreaks of the western spruce budworm. Specifically this part of the study evaluated the
response of defoliating insects to these treatments. Results showed that, in general, defoliating
insects seemed to benefit from the applied treatments, especially fertilization. The authors
concluded that overall budworm survival and prevailing trends of the outbreak were probably
determined mostly by natural enemies, and that the ultimate value of thinning and fertilizing
infested forests as a method of pest management must be viewed in the larger context of the
total effect on tree and stand productivity.
Mcgregor, M.D., Amman, G.D., Schmitz, R.F., & Oakes, R.D. (1987) Partial Cutting Lodgepole Pine Stands to
Reduce Losses to the Mountain Pine-Beetle. Canadian Journal of Forest Research-Revue Canadienne De
Recherche Forestiere, 17, 1234-1239.
McHugh, C.W., Kolb, T.E., & Wilson, J.L. (2003) Bark beetle attacks on ponderosa pine following fire in northern
Arizona. Environmental Entomology, 32, 510-522.
This study evaluated relationships between insect attacks and fire damage for ponderosa pine
in the southwestern United States. Tree mortality and insect attacks were measured on 1,367
trees for three years after a spring wildfire (4 May 1996), a summer wildfire (20 June 1996), and
a fall prescribed fire (9 September 1995) in northern Arizona. Western pine beetle,
Dendroctonus brevicomis LeConte, mountain pine beetle, D. ponderosae Hopkins, roundheaded
pine beetle, D. adjuncua Blandford, red turpentine beetle, D. valens LeConte, Ips species, and
wood borers in the Buprestidae and Cerambycidae families were found in fire-damaged trees.
The most frequently occurring insects, listed from most to least frequent, were wood borers,
red turpentine beetle, Ips spp., western pine beetle, roundheaded pine beetle, and mountain
pine beetle. Trees attacked by Dendroctonus and Ips spp. as a group had more crown damage
from fire than unattacked trees. Tree mortality 3 yr postfire was low! until crown damage by fire
exceeded 70 - 80% for unattacked trees, 40 -50% for trees with partial attacks by Dendroctonus
and IPS species, and 30-40% for trees with mass attacks. The authors concluded that several
Dendroctonus and Ips species colonize fire-damaged ponderosa pines in northern Arizona and
colonization is promoted by heavy crown damage from fire.
McLeod & Bunnell, F.L. (2005). Annotated bibliography of information related to conserving fish, wildlife, habitat
and biodiversity values in Mountain Pine Beetle (MPB) affected forests. B.C. Ministry of Water, Land and Air
Protection - Biodiversity Branch.
This report includes current scientific literature on the impacts of salvage logging due to
mountain pine beetle on a variety of other species in forested ecosystems. With the increase in
salvage logging throughout the province due to the MPB epidemic, the authors highlight the
need for conservation strategies in these large-scale salvage areas. This report is intended to
Annotated Bibliography
89
provide easy access to current scientific knowledge so operational foresters may best manage
for fish and wildlife species which may be negatively affected by these large-scale operations.
McMillin, J.D. & Allen, K.K. (2000). Impacts of Douglas-fir beetle on overstory and understory conditions of Douglasfir stands, Shoshone National Forest, Wyoming. USDA Forest Service,Rocky Mountain Region, Golden, CO.
This research focused on changes in both the overstory and understory in forests that have
been affected by Douglas-fir beetle. Significant effects of the Douglas-fir beetle infestation
included: 1) Basal area was reduced by 40 - 70 percent, tree diameter decreased by 8 - 40
percent, and the Douglas-fir component of the overstory decreased by more than 15 percent;
2) Conifer seedling regeneration increased nearly four-fold in the infested plots and 90 percent
of the regeneration was Douglas-fir; 3) The understory vegetation (forbs, grass, and shrubs) had
a three-fold increase in the infested plots compared with uninfested plots. In addition, basal
area of Douglas-fir killed by the Douglas-fir beetle was significantly correlated with initial Douglasfir basal area and percent of Douglas-fir, but not tree diameter or trees per hectare. Significant
inverse relationships were also found between post-infestation basal area and the abundance
of forbs, grass, shrubs, and understory height. The authors conclude that Douglas-fir beetle
infestations, although causing significant short-term impacts in both the overstory and
understory, probably are not changing the long-term successional patterns. Management
alternatives are presented to control Douglas-fir beetle impacts for areas where the beetle is
jeopardizing forest objectives.
Mitchell, J.L. (1994). Commercial thinning of mature lodgepole pine to reduce susceptibility to mountain pine
beetle. Victoria, British Columbia, Canada: FRDA Research Program, Research Branch, BC Ministry of Forests
and Lands.
This study evaluated the influence of commercial thinning and fertilizer application on the
susceptibility of lodgepole pine to mountain pine beetle in 3 sites in southeastern British
Columbia in 1992. It also documents the productivity and costs of the commercial thinning (to
4- and 5-m spacing) and clear felling harvesting operations on 2 of the sites. The authors
compare the productivity of the harvesting equipment and operating practices used during the
felling and skidding phases on each treatment, and they also examine the operational feasibility
of commercial thinning. They conclude that commercial thinning costs more than clear felling
but could reduce the risk of attack and ensure that the stand is available for future harvest if
infestation by mountain pine beetle is likely. Reducing the volume of timber lost to beetle damage
by preventing epidemics could justify the higher cost of thinning as an investment in the future.
Mitchell, R.G. (1990). Effects of prescribed fire on insect pests. In Natural and Prescribed Fire in Pacific Northwest
Forests (eds J.D. Walstad, S.R. Radosevich & D.V. Sandberg), pp. 111-116. Oregon State University Press,
Corvallis, OR.
This book section describes the impact of prescribed fire on insect pests in the Pacific
Northwest. The authors state that fire has long been a part of many northwest ecosystems, and
its suppression has in some forest systems greatly increased the threat by insect pests. He
mentions that in ponderosa pine, crown scorch can invite attack by bark beetles; however, the
pest problems generated by prescribed burning are mostly minor and usually can be avoided
by careful planning to ensure suitable burn intensity.
90
Scientific Basis for Forest Management in the U.S. Inland West
Mitchell, R.G. & Preisler, H.K. (1991) Analysis of Spatial Patterns of Lodgepole Pine Attacked by Outbreak
Populations of the Mountain Pine-Beetle. Forest Science, 37, 1390-1408.
This study analyzed five years of mountain pine beetle attacks on lodgepole pine in an early
outbreak situation. The model showed that the probability of trees being colonized increased
significantly as the outbreak gained momentum, but only as long as the food supply (trees with
dbh greater-than-or-equal-to 23 cm) was abundant. The study found that big trees were
important to outbreaks beyond simply generating beetles, and that many trees were colonized
only because they were close to other trees under attack.
Mitchell, R.G. & Preisler, H.K. (1998) Fall rate of lodgepole pine killed by the mountain pine beetle in central
Oregon. Western Journal of Applied Forestry, 13, 23-26.
The fall rate of nearly 600 lodgepole pines killed by the mountain pine beetle was investigated
in thinned and unthinned stands at 2 sites in central Oregon. Snags began falling 3 years after
death in thinned stands and 5 years in unthinned stands. Small trees fell slightly faster than large
trees in thinned stands, but tree size was not a factor in the fall rate in unthinned stands. In
thinned stands, 50% were down in 8 years and 90% were down in 12 years. In unthinned
stands, 50% were down in 9 years and 90% were down in 14 years. All beetle-killed trees broke
off at the ground when they fell. The authors concluded that the rate that trees fall in different
environments may be related to the speed of bole decay at the ground level.
Murphy, T.E.L., Adams, D.L., & Ferguson, D.E. (1999) Response of advance lodgepole pine regeneration to
overstory removal in eastern Idaho. Forest Ecology and Management, 120, 235-244.
Twenty-two stands of advance growth lodgepole pine released with overstory removal were
sampled to determine height growth response in the Targhee National Forest, Idaho. In the early
1960s, epidemic populations of the mountain pine beetle in the forest had killed thousands of
acres of mature lodgepole pines over 15 yrs. Tree and site characteristics correlated with release
response of the advance growth were identified, and a mathematical model was developed to
predict height growth in years 6 through 10 after release as a function of residual overstorey
basal area, height at release, percentage rock cover, 5-year cumulative growth prior to release,
logging damage, stand altitude, and habitat type. Lodgepole pine responded to release with
increased height growth in 97% of the trees sampled. Growth was similar to that of
unsuppressed trees. Height growth was best when the entire overstory was removed and logging
damage was avoided. Taller trees generally did not respond as well as shorter trees. However,
trees growing fast before harvest continued to grow fast regardless of their height at release.
The authors make recommendations for selecting stands of advance lodgepole pine to release.
Muzika, R.M. & Liebhold, A.M. (2000) A critique of silvicultural approaches to managing defoliating insects in
North America. Agricultural and Forest Entomology, 2, 97-105.
A variety of silvicultural techniques have been suggested for managing forest defoliating insects.
The objectives typically focus on minimizing defoliation or minimizing damage from defoliation.
The authors argue that the theoretical foundations of many approaches have been built upon
observation and correlation, that very little reliable empirical evidence exists to support the
objectives of silvicultural manipulations, and that existing experimental data have yielded
inconsistent results. They review the conceptual framework and underlying assumptions of the
major silvicultural approaches recommended or in use in North America. They recommend that
Annotated Bibliography
91
well-designed, long-term studies are needed to clarify the effect of silviculture on defoliators
and their effect on forests.
Natural Resources Canada, Canadian Forest Service (2004). Mountain pine beetle management: a guide for
small woodland operations. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre,
Mountain Pine Beetle Initiative.
This guide, written for non-foresters, provides recommendations for management of mountain
pine beetle on small-scale woodlands in western Canada. The guide includes a description of
the mountain pine beetle (e.g. life cycle, hosts, natural control factors, dispersal and colonization,
and infestation cycle), mountain beetle management practices, forest management planning,
and a list of contact information for key organizations and government agencies.
Negron, J.F. (1998) Probability of infestation and extent of mortality associated with the Douglas-fir beetle in the
Colorado Front Range. Forest Ecology and Management, 107, 71-85.
This study utilized infested and uninfested areas within Douglas fir stands affected by the
Douglas-fir beetle in the Colorado Front Range, to develop models that predict probabilities of
infestation. Regression trees and linear regression analysis were used to model amount of tree
mortality in terms of basal area killed in infested stands. The data suggests that Douglas-fir
beetle-attacked stands contain a high percentage of the basal area represented by Douglas-fir,
high tree densities, and poor growth during the last 5 years prior to attack. Trees prone to attack
by the Douglas-fir beetle within infested points also exhibited reduced growth rates. Tree and
linear regression analysis indicate that initial amount of Douglas-fir basal area can be used as
a predictor variable for the amount of basal area affected.
Negron, J.F. & Popp, J.B. (2004) Probability of ponderosa pine infestation by mountain pine beetle in the Colorado
Front Range. Forest Ecology and Management, 191, 17-27.
This study utilized data from north-central Colorado to develop and empirical model for probably
of infestation by mountain pine beetle in ponderosa pine of Colorado’s Front Range based on
forest conditions. Mountain pine beetle-infested plots exhibited higher basal area and stand
density index (SDI) for ponderosa pine and for all tree species combined, and higher number
of ponderosa pine trees per hectare. Within infested plots, infested trees were larger in diameter
at breast height and in the dominant and co-dominant crown positions. A classification tree
model indicated that the likelihood of infestation by mountain pine beetle is 0.71 when
ponderosa pine basal area is >17.1 m(2)/ha at the stand level. A second plot-level model
indicated that the probability of infestation increased with increasing ponderosa pine SDI,
ponderosa pine quadratic mean diameter, and total basal area. For individual trees within
infested plots the likelihood of infestation was 0.77 for dominant or co-dominant trees >18.2 cm
in diameter at breast height. Results are consistent with other studies that have documented
increased likelihood of infestation or enhanced mortality levels or both as a result of higher host
type stocking. The simple models developed should help to guide silvicultural treatments and
restoration efforts by establishing stocking levels below which mountain pine beetle-caused
mortality is less likely, particularly in the dry sites and poor growing conditions characteristic of
the Colorado Front Range.
92
Scientific Basis for Forest Management in the U.S. Inland West
Oester, P.T., Emmingham, W.H., & Larson, P. (2005) Thinning alternatives for ponderosa pine: Tools and strategies
for family forest owners. Western Journal of Applied Forestry, 20, 216-223.
This case study examined periodic growth response of ponderosa pine 5 and 13 years after
installation of a trial including three thinning regimes and an unthinned option in the Wallowa
Mountains of northeast Oregon. The authors note that density management of ponderosa pine
forests is critical for control of beetles, reducing risk of wildfire and capturing monetary, aesthetic,
and ecological values. This study analyzed mean tree diameter growth and periodic board foot
volume growth of 8-in. diameter and larger trees for the four treatments applied to 85-100-yearold stands. The authors suggest ways that family forest owners and their advisors whose
management goals include reducing fire and beetle risk and producing timber value can use
the results of this case study with the stand density index (SDI) to evaluate thinning options.
Significant increases were found after 13 years in mean diameter growth of trees and periodic
board foot volume growth per tree in the wide and free treatments compared to narrow and
control. Thinning to 80 ft(2) of basal area or the lower management zone SDI in previously
unmanaged, 85-year-old ponderosa pine stands provided for faster tree growth, lower risk of
mortality from mountain pine beetle, and no appreciable sacrifice in value of stand growth. Total
wood fiber production was better for narrow and control, but with greatly increased fire and
beetle risk. This work substantiates research results that thinning to carefully prescribed stocking
levels can increase volume growth per tree and maintain reasonable stand value growth even
though cubic volume growth is diminished. The authors conclude that resulting changes in
stand structure and reduced beetle and fire threats improve the odds that family forestland will
generate their full potential of monetary and ecological benefits.
Olsen, W.K., Schmid, J.M., & Mata, S.A. (1996) Stand characteristics associated with mountain pine beetle
infestations in ponderosa pine. Forest Science, 42, 310-327.
Stand characteristics associated with mountain pine beetle infestations within a 2.15 acre plot
were analyzed in ponderosa pine stands in South Dakota. Trees per acre, basal area, quadratic
mean diameter, minimum diameter, and the range of diameters in MPB infested groups were
significantly different from those in noninfested groups. Maximum diameter was not different
between infested and noninfested groups. The authors also challenged the work of Mitchell and
Priesler (1991), suggesting that MPBs do not necessarily preferentially attack the largest diameter
trees in a stand. Results are discussed in regard to the mountain pine beetle-host relationship
and stand management. Results should be considered in light of the small area sampled.
Parry, D.L. & Pacific Northwest Research, S. (1996) Lumber recovery and deterioration of beetle-killed Douglasfir and grand fir in the Blue Mountains of eastern Oregon. In General technical report PNW, Vol. GTR-376, pp.
24. U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, Or. 333 S.W. First
Ave., Portland 97208-3890.
This study evaluated the effect of time since death over a 4-year period on the amount of usable
product volume and value, and to determine the species of fungi associated with wood
deterioration in the stems of Douglas-fir and grand fir trees killed by bark beetles in northeastern
Oregon. Two-year-dead Douglas-fir recovered about 8 percent less lumber volume than live
and 1-year dead Douglas-fir and all classes of dead grand fir. Three- and four-year dead
Douglas-fir combined lost another 7 percent in lumber volume. Average lumber value (dollars
per thousand lumber tally) and average log value (dollars per hundred cubic feet) analysis
showed no difference among the live and 1-year-dead Douglas-fir samples. Average log value
Annotated Bibliography
93
decreased about $60 from the live class to the grand fir dead class and another $60 for the
Douglas-fir dead. Contrary to popular belief, the grand fir did not deteriorate as fast as the
Douglas-fir or lose as much value as expected.
Powell, D. (1999). Suggested stocking levels for forest stands in northeastern Oregon and southeastern
Washington: an implementation guide for the Umatilla National Forest. U.S. Department of Agriculture, Forest
Service, Umatilla National Forest, Pendleton, Oregon.
The authors present suggested stocking levels for forest stands in northeastern Oregon and
southeastern Washington, to help guide management in the Umatilla National Forest.
Powers, J.S., Sollins, P., Harmon, M.E., & Jones, J.A. (1999) Plant-pest interactions in time and space: A Douglasfir bark beetle outbreak as a case study. Landscape Ecology, 14, 105-120.
A conceptual model of Douglas-fir bark beetle dynamics and associated host tree mortality
across multiple spatial and temporal scales was developed and then used to study the
association between the occurrence of beetle-killed trees and factors that might render trees
more susceptible to attack. Longterm records of beetle kill showed that beetle epidemics were
associated with windstorms and drought at statewide and local spatial scales. At the landscape
scale, beetle kill was associated with (i) portions of the landscape that were potentially drier
(southern aspects, lower elevations) and (ii) portions of the landscape that had more mature and
old-growth conifer vegetation. At the scale of the individual tree, there was not a strong
relationship between beetle kill and resistance to attack measured by tree growth rate prior to
attack. The results indicate that landscape-scale phenomena and temporal patterns are more
strongly correlated with beetle-kill events than recent grow! th history at the scale of individual
trees. The authors suggest that this multi-scale approach is useful for elucidating the relative
roles of fine- versus coarse-scale constraints on ecological processes.
Preisler, H.K. & Mitchell, R.G. (1993) Colonization Patterns of the Mountain Pine-Beetle in Thinned and
Unthinned Lodgepole Pine Stands. Forest Science, 39, 528-545.
Outbreak populations of the mountain pine beetle in central Oregon were analyzed with an
autologistic regression model to evaluate colonization patterns in thinned and unthinned plots
of lodgepole pine. Results confirmed previous observations that beetle attacks in unmanaged
stands were related to tree diameter and spacing among trees. Beetles showed a decided
preference for colonizing trees with large diameters. Trees with small diameters were rarely
attacked unless they were close to other trees under attack. Thinned plots were initially
unattractive to beetles, but when attacks occurred, colonization was not very different from the
pattern in unthinned plots. Vigor was not a significant covariate for estimating probability of
attack in the unthinned plots. It was significant for one of the thinned plots, however, and
marginally significant for another. Only one tree was colonized in a third thinned plot that had
the widest spacing and the greatest vigor. A surprise was that some of the oldest trees on thinned
plots appeared resistant to attack; their resistance was unrelated to diameter, vigor, or position
relative to other attacked trees.
94
Scientific Basis for Forest Management in the U.S. Inland West
Quigley, T.M., Hayes, J.L., Starr, L., & Daterman, G.E. (2001) Improving forest health and productivity in eastern
Oregon and Washington. Northwest Science, 75, 234-251.
This paper discusses the effects of forest health and productivity decline in eastern Oregon and
Washington, and suggests a framework for integrating the available models and information to
improve the situation. The authors discuss research projects undertaken by the Forest Health
and Productivity Initiative of the Pacific Northwest Research Station to develop options for
managing insect, disease, and fire disturbances in order to improve ecosystem integrity, to
integrate biophysical and socioeconomic considerations, to identify linkages across scales, and
to fill significant knowledge gaps at the mid or broad scale. The authors also discuss the need
for adequate resources to plan and implement actions, and motivation of resource specialists
and the public to undertake the actions, and acceptance by the public, interest groups,
agencies, and policy makers of management actions proposed.
Radeloff, V.C., Mladenoff, D.J., & Boyce, M.S. (2000) Effects of interacting disturbances on landscape patterns:
Budworm defoliation and salvage logging. Ecological Applications, 10, 233-247.
This study evaluates salvage logging in fire-suppressed jack pine stands following insect defoliation
in northwestern Wisconsin. Although outside of the geographic area of the inland northwest, the
methods of evaluating stand responses after salvage logging may be of interest. The study
evaluated landscape pattern changes caused by the interaction of natural disturbances and forest
management. The authors utilized Landsat TM imagery to classify forests prior to insect outbreak,
and clearcuts following outbreaks. The authors concluded that logging rates were highest on the
most infertile soils, and on private, industrial forest land. Annual logging rates of different
landowners were 3-6 times higher during the outbreak than previous to it. Salvage cut sizes were
larger than clearcuts prior to the outbreak. New cuts were mostly located next to previous cuts,
thus increasing the size of openings on the landscape. The authors cite studies indicating that
defoliation and subsequent salvage logging can create new habitat for some declining open-habitat
species. The authors note that landscape pattern changes due to multiple interacting
disturbances have rarely been studied, and that the interaction of jack pine budworm defoliation
and salvage logging have substantially changed landscape patterns in the region.
Ravlin, F.W. (1991) Development of Monitoring and Decision-Support Systems for Integrated Pest-Management
of Forest Defoliators in North-America. Forest Ecology and Management, 39, 3-13.
This paper discusses several computer-aided decision-support tools such as models and GIS
to facilitate integrated pest management and monitoring. This paper reviews the advances made
with monitoring systems and decision-support tools with reference to the major defoliators of
North American forests. Research accomplished by the Douglas-fir tussock moth, spruce
budworm, and gypsy moth programs is reviewed.
Reynolds, K.M. & Hessburg, P.F. (2005) Decision support for integrated landscape evaluation and restoration
planning. Forest Ecology and Management, 207, 263-278.
The authors discuss the range and variation in historical forest spatial patterns in relation to
restoration efforts of inland northwest forests. They highlight the dramatic changes in land use
in the inland northwest over the past two centuries of human settlement and land use. They
describe that spatial patterns of forest structural conditions, tree species composition, snags
and down wood, and temporal variation in these patterns, have been altered to such an extent
Annotated Bibliography
95
that the natural ebb and flow of terrestrial habitats and their linkages has been disrupted. Closely
coupled with these changes, fire and other disturbance processes in most dry and many mesic
forest types have also shifted, with a bias for increased severity and extent. The authors discuss
how the historic range of variation can be used to evaluate current landscape patterns to identify
changes that may have important ecological implications. They describe a decision support
system for integrated landscape evaluation and restoration planning which compares
subwatersheds within an ecoregion and prioritizes watersheds for possible management actions
related to landscape restoration and maintenance. The authors cite advantages to a decisionsupport approach that treats evaluation and planning as distinct but integrated phases: (1) the
overall decision process is rendered conceptually simpler and (2) practical considerations of
efficacy and feasibility of management actions can be easily accommodated.
Ross, D.W. (1995) Short-term impacts of thinning ponderosa pine on pandora moth densities, pupal weights, and
phenology. Western-Journal-of-Applied-Forestry, 10, 91-94.
In studies on the Deschutes National Forest, Oregon, second-growth ponderosa pine (Pinus
ponderosa) stands with outbreak populations of the pandora moth (Coloradia pandora) were
thinned from below, removing about half of the basal area. Thinning had no effect on pandora
moth pupal density or weight, or emerging adult density in the following generation. However,
adult emergence and egg hatch occurred 7-10 days earlier in thinned plots compared with
unthinned plots. Egg and larval densities on a foliage weight basis were not significantly different
between thinned and unthinned plots. Thinning stands infested with pandora moth will not
significantly affect the course of an outbreak for at least one generation. Timing of direct controls
for the pandora moth should consider the effect of stand density on insect phenology.
Ross, D.W. & Daterman, G.E. (1995) Efficacy of an antiaggregation pheromone for reducing Douglas-fir beetle,
Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae), infestation in high risk stands. Canadian
Entomologist, 127, 805-811.
The Douglas-fir beetle antiaggregation pheromone MCH, was applied to stands at high risk for
infestation. Catches of Douglas-fir beetles were significantly lower on MCH-treated plots
compared with untreated plots. In contrast, catches of the most abundant predator, Thanasimus
undatulus (Say), were unaffected by the MCH treatment. The percentage of Douglas-fir
[Pseudotsuga menziesii (Mirb.) France] trees greater than or equal to 20 cm dbh that were
mass attacked was significantly lower on treated plots (0.2%) compared with untreated plots
(8.5%), MCH alone was effective in reducing the probability of Douglas-fir beetle infestations
occurring in high risk stands.
Saab, V.A. & Dudley, J.G. (1998) Responses of cavity-nesting birds to stand-replacement fire and salvage logging
in ponderosa pine/Douglas-fir forests of southwestern Idaho. USDA Forest Service Rocky Mountain Research
Station Research Paper.
In spring 1994, the USFS initiated long-term studies on bird responses to different fire conditions
in ponderosa pine/Douglas-fir forests of southwestern Idaho. The first phase of the project
evaluated effects of high-intensity wildfire on cavity-nesting birds and their associated habitats.
The authors monitored more than 600 nests of nine cavity-nesting bird species and measured
vegetation. Nests and vegetation were monitored in three treatments: standard-cut salvage
logged, wildlife-prescription salvage logged, and unlogged controls. In salvage-logged units about
50% of the trees were harvested. Lewis’ Woodpecker was the most abundant (208 nests) and
96
Scientific Basis for Forest Management in the U.S. Inland West
successful cavity nester on the 2-4 year-old burns, while Black-backed and White-headed
woodpeckers were rare (23 nests). Lewis’ Woodpecker and American Kestrel experienced the
highest nesting success in the salvage-logged units, whereas Northern Flicker and Hairy
Woodpecker were most successful in the unlogged units. All bi! rd species selected nest sites
with higher tree densities than that measured at random sites, and cavity nesters as a group
selected clumps of snags rather than snags that were retained in uniform, evenly-spaced
distributions. The authors discuss management implications of stand-replacement fire and postfire salvage logging for cavity-nesting birds.
Safranyik, L., Linton, D.A., Shore, T.L., & Hawkes, B.C. (2001). The effects of prescribed burning on mountain
pine beetle in lodgepole pine. Victoria, Canada: Pacific Forestry Centre, Canadian Forest Service.
Incidence of attack and brood production by mountain pine beetle in lodgepole pine were
assessed following a 600-ha controlled burning in Tweedsmuir Park in central British Columbia.
Varying levels of fire intensity resulted in various degrees of crown scorch and tree bole charring.
In trees attacked prior to the burn, brood density was significantly reduced in the two highest
burn intensity classes compared to the other classes. On average, beetle production per tree in
burned trees was reduced by almost half compared to trees with no evidence of bole charring,
and population increase in the burned area was reduced to a static level. The year following the
fire, mean attack, egg gallery and brood density taken over all burn intensity classes were
significantly lower than outside the burn. However, on a per attack basis brood survival in trees
within the burn was similar to that in trees outside the burn.
Safranyik, L., Shore, T.L., Carroll, A.L., & Linton, D.A. (2004) Bark beetle (Coleoptera : Scolytidae) diversity in
spaced and unmanaged mature lodgepole pine (Pinaceae) in southeastern British Columbia. Forest Ecology
and Management, 200, 23-38.
This study evaluated variation in the number and diversity of bark beetles in spaced mature
lodgepole pine stands in southeastern British Columbia in relation to location (site), spacing
treatment and years following treatment. It also investigated the incidence of bark beetle attacks
on the remaining trees and the mean dates of emergence from stumps and of capture in flight
traps for the common species. The mean density of bark beetles emerged from stumps was
different among sites and years but not between spacing treatments. There was no statistically
significant variation in the number of bark beetle species captured in flight traps by site, spacing
treatment, years, or spacing treatment and years. Significantly more bark beetles were captured
in the 4 m x 4 m spacing treatment than in the control. The number of bark beetles captured
was the highest in the first 2 years following treatment. Up to 26 species of bark beetles,
excluding ambrosia beetles, were captured in flight barrier traps. There was no difference in
species diversity by site or treatment indicating that species diversity in mature lodgepole pine
is relatively stable over large areas. The majority of infested trees contained Ips sp.,
Dendroctonus valens and D. murrayanae. Of the seven trees attacked by mountain pine beetle,
only one tree was located in a spaced plot.
Safranyik, L., Shore, T.L., & Linton, D.A. (1999) Attack by bark beetles (Coleoptera : Scolytidae) following spacing
of mature lodgepole fine (Pinaceae) stands. Canadian Entomologist, 131, 671-685.
Variation in bark beetle attack following spacing of mature lodgepole pine stands in southeastern
British Columbia was analyzed in relation to stand location (site), spacing treatment, and
harvesting injury. There was no statistically significant difference in the numbers of attacked
Annotated Bibliography
97
trees among sites or treatments. However, in the spaced plots 94.3% of the attacked trees
sustained harvesting injury or were located adjacent to skid trails. Dendroctonus valens LeConte
was the dominant species attacking trees on the two drier sites, and Dendroctonus murrayanae
Hopkins was the dominant species on the third site. There was no statistically significant
variation in the percentage of attacked stumps among sites or spacing treatments. On average,
80.7% of the stumps were attacked; attacked stumps had larger diameters than unattacked
stumps. Thirteen species of bark beetles were found attacking stumps. Hylurgops porosus
LeConte was the most numerous species at all three sites. The! study results indicated that
stand characteristics affected species assemblages and abundances of bark beetle species that
attacked stumps. Management practices that minimize injury to trees during the spacing
operations are emphasized to reduce attack by bark beetles.
Schmid, J.M. & Mata, S.A. (1992) Stand density and mountain pine beetle-caused tree mortality in ponderosa
pine stands. Research Note RM-515, US Department of Agriculture, Forest Service.
Mountain pine beetle-caused tree mortality was monitored in three ponderosa pine plots partially
cut to growing stock levels (GSL) of 60, 80, and 100 and an uncut control. Tree mortality
occurred in all plots prior to the partial cutting. No mountain pine beetle-caused mortality has
occurred in the partially cut plots since cutting, but tree mortality has continued in the uncut
stand. Stands cut to GSL (equivalent to ft^2 basal area) 100 appear less susceptible to attack.
Schmid, J.M., Mata, S.A., & Olsen, W.K. (1995) Microclimate and mountain pine beetles in two ponderosa pine
stands in the Black Hills. Research Note RM-RN-532, US Department of Agriculture, Forest Service.
The authors characterized air and bark temperatures, horizontal wind speed, and solar radiation
for ponderosa pine stands considered susceptible and nonsusceptible to attack by the mountain
pine beetle in the Black Hills of South Dakota. South-side bark temperatures during midday
hours, maximum differences between north-side bark temperatures and air temperatures,
maximum differences between south-side bark temperatures and air temperatures, and solar
radiation were greater in the nonsusceptible stand than in the susceptible stand. Air
temperatures, north-side bark temperatures, and horizontal wind speeds were not significantly
different between the two stands. The potential influence of these factors on stand susceptibility
to beetle attack is evaluated.
Schowalter, T.D. & Withgott, J. (2001) Rethinking insects. What would an ecosystem approach look like?
Conservation Biology in Practice, 2, 10-16.
The authors suggest that, when managers are considering controlling insect pests, they should
ask whether they are treating a cause or just a symptom. They emphasize that destructive
insects outbreaks often result, directly and indirectly, from past human actions that made forests
more susceptible to insect outbreaks. These actions include establishment of monocultures,
fragmentation of habitat, introduction of exotic species, and fire suppression. They emphasize
the role of forest insects in maintaining forest health. They also emphasize that, where risks of
fires are acceptable, insect outbreaks can correct past inappropriate management actions.
98
Scientific Basis for Forest Management in the U.S. Inland West
Scott, D.W. (1996). Insect response to altered landscapes: historic range of variation of insects. USDA Forest
Service Report BMZ-97-2. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, WallowaWhitman National Forest, Blue Mountains Pest Management Zone, LaGrande, OR.
This report draws on previous research to describe the historic range of variability for several
forest insect pest species in the inland northwest.
Scott, D.W. (2000). Population analysis of Douglas-fir tussock moth in northeastern Oregon and southeastern
Washington, 1999. USDA Forest Service, Wallowa-Whitman National Forest, LaGrande, OR.
The author reviews previous papers on Douglas-fir tussock moth biology and stand susceptibility,
and analyzes DFTM populations on forests in northeastern Oregon and southeastern Washington.
Shepherd, R.F. (1994) Management Strategies for Forest Insect Defoliators in British-Columbia. Forest Ecology
and Management, 68, 303-324.
This paper synthesizes outbreak characteristics of common defoliating insects in British
Columbia. The authors distinguish between two types: those with fast-cycling outbreaks and
those with sustained outbreaks. Species with fast-cycling outbreaks rise quickly to visible
defoliation levels, cause significant growth loss, tree deformation and mortality, and disappear
just as quickly. Impact is closely related to the severity of defoliation during the first year of an
outbreak; consequently, the objective of managing these species should be to reduce
populations before defoliation occurs, i.e. to prevent the outbreak. Species with sustained
outbreaks cause significant growth losses only after defoliation continues for a number of years.
Tree mortality usually is not important except where regeneration is being nurtured under a
selective or shelterwood silvicultural system. Impact can be significant over the life of a stand
because of the length and frequency of outbreaks, but treatments effective for only 1 year usually
cannot be justified except where it is important to retain a full crown. Long-term cultural methods
appear to be the preferred management system and, of these, utilizing nonhost species or
resistant or phenologically asynchronous host species may be the best option. The authors
conclude that determining the location of expected outbreaks is an important component of a
management system, and identifying stands by frequency of outbreak within zones of climatic
suitability would be useful in selecting treatment areas.
Speer, J.H., Swetnam, T.W., Wickman, B.E., & Youngblood, A. (2001) Changes in pandora moth outbreak
dynamics during the past 622 years. Ecology, 82, 679-697.
Episodic outbreaks of pandora moth (Coloradia pandora Blake), a forest insect that defoliates
ponderosa pine and other pine species in the western United States, have recurred several
times during the 20th century in south-central Oregon. The authors collected and analyzed treering samples from stands affected by recent outbreaks of pandora moth to develop a long-term
record of outbreaks. Using the pandora moth tree-ring signature, they reconstructed a 622year record of 22 individual outbreaks in 14 old-growth ponderosa pine stands - the longest
regional reconstruction of forest insect outbreak history in North America. Intervals between
outbreaks were highly variable, ranging from 9 yr to 156 yr. Twentieth-century outbreaks were
not more extensive, severe, or longer in duration than outbreaks in previous centuries, but there
was an unusual 60-yr reduction in regional activity during 1920-1980. The changing dynamic
of pandora moth populations highlights the need to evalu! ate historical factors that may have
influenced this system such as climatic variations, forest fires, and human land uses. Although
Annotated Bibliography
99
cyclical dynamics in animal populations have most commonly been attributed to endogenous,
ecological processes (e.g., “delayed density dependence,” predators, pathogens, and parasites)
our findings suggest that exogenous processes (e.g., climatic oscillations) may also be involved.
Starr, L., Hayes, J.L., Quigley, T.M., Daterman, G.E., & Brown, S. (2001) A framework for addressing forest health
and productivity in eastern Oregon and Washington. Northwest Science, 75, 1-10.
This paper proposes a framework for evaluating healthy forests and rangelands in eastern
Oregon and Washington. The authors suggest that, with an improved understanding of
disturbance processes and careful management of the drivers of disturbance, it is possible to
enhance ecosystem resiliency. As an aid to managers in determining actions that may be
successful in restoring resilience to ecosystems, the authors describe linkages among
components that may enable managers to harness beneficial effects of disturbances while
minimizing the adverse effects. A conceptual framework presented here identifies relations
among factors that managers can influence, and that are important to ecological processes and
outcomes. Integrating social and economic components helps managers to balance what the
land will allow, what people want, and what society can afford. Influence diagrams help identify
important linkages and the areas where research may help to weigh tradeoffs.
Steeger, C. & Hitchcock, C.L. (1998) Influence of forest structure and diseases on nest-site selection by redbreasted nuthatches. Journal of Wildlife Management, 62, 1349-1358.
This study focuses on a “weak cavity excavator” ñ the red-breasted nuthatch, rather than on the
more traditionally studied large, strong cavity excavators such as woodpeckers. The authors note
that these birds, though smaller and less limited by the availability of large trees, are more
dependent on suitably softened wood. The authors focused on structural habitat features, and
also other forest health issues, including Armillaria root disease, stemwood decay, mountain
pine beetle infestation, and dwarf mistletoe. The authors found that red-breasted nuthatches
nested at higher densities on cutblocks with more dead trees (snags) and higher levels of root
disease. Cavity nesting of nuthatches was influenced by both forest structure and the disease
agents that contribute to it. They recommend that standing diseased and dead trees be retained
in patches during logging operations, to ensure worker safety and to limit the spread of root
diseases. The authors conclude that wildlife values not only should be incorporated into timber
harvesting regulations but also should be considered when planning activities designed to
improve forest health for timber production.
Stuart, J.D., Agee, J.K., & Gara, R.I. (1989) Lodgepole pine regeneration in an old, self-perpetuating forest in south
central Oregon. Canadian Journal of Forest.Research, 19, 1096-1104.
Historical regeneration patterns and regeneration requirements were studied in a lodgepole pine
forest at 1800 m alt. in the Fremont National Forest. The forest was multi-aged, with episodic
regeneration pulses correlated with mountain pine beetle outbreaks or fire. The amount of
regeneration was a function of disturbance intensity. Tree ring indices showed growth decline
prior to pine beetle outbreaks. Radial tree growth improved following disturbance. Successful
lodgepole pine regeneration was limited by soil moisture and partly by microclimate. Shading
did not inhibit seedling establishment, but, rather, it ameliorated excessive evapotranspiration,
heat and frost. Differences in stand structure among climax lodgepole pine stands in the Rocky
Mountains, Sierra Nevada, and S. central Oregon were shown to be related to disturbance type,
frequency and intensity.
100
Scientific Basis for Forest Management in the U.S. Inland West
Swetnam, T.W., Wickman, B.E., Gene, P.H., & Baisan, C.H. (1995) Historical patterns of western spruce budworm
and Douglas-fir tussock moth outbreaks in the northern Blue Mountains, Oregon, since AD 1700. Research
Paper - US Department of Agriculture, Forest Service.
Dendroecology methods were used to reconstruct a three-century history of western spruce
budworm and Douglas-fir tussock moth outbreaks in the Blue Mountains of NE Oregon.
Budworm outbreaks were more confidently reconstructed than were tussock moth outbreaks.
Since AD 1700, at least eight regional budworm outbreaks have occurred at intervals of about
21 to 53 yrs. Reduced radial growth caused by defoliation lasted from about 13 to 17 yrs. Two
regional budworm outbreaks occurred during the 19th century, and at least three and possibly
four regional outbreaks have occurred during the 20th century.
The Wilderness Society & National Audubon Society (1996). Salvage Logging in the National Forests: an
Ecological, Economic, and Legal Assessment. The Wilderness Society and National Audubon Society,
Washington, D.C.
This report describes widespread damage to national forests from salvage logging, and suggests
ways that forest management can be improved based on sound science.
Torgersen, T.R., Bull, E.L. 1995. Downed logs as habitat for forest-dwelling ants—the primary prey of pileated
woodpeckers in northeastern Oregon. Northwest Science, 69, 294-303.
Torgersen, T.R. (2001) Defoliators in eastern Oregon and Washington. Northwest Science, 75, 11-20.
Four main defoliating insects which are major disturbance agents affecting forest health and
productivity in eastern Oregon and Washington are discussed: western spruce budworm,
Douglas-fir tussock moth, pandora moth, and larch casebearer. The paper discusses interactions
of defoliators with other system components and natural regulatory processes, as well as
monitoring and suppression techniques using pheromone traps, chemical and biological
materials. The author explains that such suppression projects have been largely ineffective in
changing the outbreak behavior of these insects, and that some suppression materials have
undesirable side effects on non-target insects and ecological processes. The author also
describes some decision-support and risk assessment tools, and concludes that for most
defoliators, the recommended strategy is preventative: silvicultural treatment to promote a
diversity of tree species, stand structures, and moderate stocking levels.
Turner M.G., Romme, W.H., & Gardner, R.H. 1999. Prefire heterogeneity, fire severity, and early postfire plant
reestablishment in subalpine forests of Yellowstone National Park, Wyoming. International Journal of Wildland
Fire, 9, 21-36.
Abstract: The 1988 fires in Yellowstone National Park provided an opportunity to study effects
of a large infrequent disturbance on a natural community. This study addressed two questions:
(1) How does prefire heterogeneity of the landscape affect postfire patterns of fire severity? and
(2) How do postfire patterns of burn severity influence plant reestablishment? At three sites,
100 sampling points were distributed regularly in a 1-km x 1-km grid and sampled annually
from 1989 to 1992. Information was recorded on fire severity (damage to trees, depth of ash and
soil charring, and percent mineral soil exposed); pre-fire forest structure (forest successional
stage; tree density; tree species; tree size; and evidence of pre-fire disturbance by mountain pine
beetle [Dendroctonus ponderosae Hopk.] or mistletoe [Arceuthobium americanum Nutt. ex
Annotated Bibliography
101
Engelm.]); post-fire percent cover of graminoids, forbs, and low shrubs; number of lodgepole
pine (Pinus contorta var. latifolia Engelm.) seedlings; and general topographic characteristics
(slope and aspect). Fire severity was influenced by successional stage, with older stands more
likely to be in the more severe burn class, and by tree diameter, with tree damage diminishing
with tree size. Prefire bark beetle and mistletoe damage also influenced fire severity; severe
prefire damage increased the likelihood of crown fire, but intermediate prefire damage reduced
the likelihood of crown fire. Fire severity was not influenced by slope, aspect, or tree density.
Postfire percent vegetative cover and density of lodgepole pine seedlings varied with burn
severity. In lightly burned areas, percent cover returned to unburned levels by 1991. In severely
burned areas, total percent cover was about half that of unburned areas by 1992, and shrub
cover remained reduced. Recruitment of lodgepole pine seedlings was greatest during the
second postfire year and in severe-surface burns rather than in crown fires. Continued m!
onitoring of vegetation dynamics in Yellowstoneís burned forests will contribute to our
understanding of successional processes following a disturbance that was exceptional in its size
and severity.
Wagner, R.G. (1994) Toward Integrated Forest Vegetation Management. Journal of Forestry, 92, 26-30.
The authors compare the less-visible damage to desired trees from surrounding vegetation with
the more clearly visible damage produced by most insect and disease pests. They explain that
such damage from surrounding vegetation results primarily in lost stand development potential.
The authors conclude that vegetation management used throughout the life of a stand not only
reduces this damage but also provides one of the best opportunities to influence the
composition, growth, and form of developing stands.
Wales, B.C. (2001) The management of insects, diseases, fire, and grazing and implications for terrestrial
vertebrates using riparian habitats in eastern Oregon and Washington. Northwest Science, 75, 119-127.
This paper describes the effects of disturbance agents on riparian habitats in eastern Oregon
and Washington - habitats that are essential for many species of vertebrates. Disturbances from
insects and disease likely have strong effects on cavity nesters and insect feeders, and use of
Bt (Bacillus thuringiensis) to control insect pests decreases the food supply for insectivores.
Most fire effects on terrestrial vertebrates are through changes in habitat, food, and competitors,
and responses to fire are variable and species specific. Salvage logging likely has negative effects
for species that use dead and dying trees. There are almost no studies on how landscape-level
vegetation patterns (including riparian corridors) contribute to the viability of wildlife populations.
The authors notes that managers often choose to buffer riparian areas from harvest, spraying,
and prescribed fire, but there are no decision-support tools or guidelines for management of
riparian habitat for terrestrial vertebrates.
Waring, R.H., Savage, T., Cromack, K., & Rose, C. (1992) Thinning and Nitrogen-Fertilization in a Grand Fir
Stand Infested with Western Spruce Budworm. 4. an Ecosystem Management Perspective. Forest Science,
38, 275-286.
Part four of four-part study testing the effects of thinning and nitrogen fertilization in grand fir
stands in Oregon that had been defoliated by western spruce budworm. Thinning combined
with fertilization improved growth efficiency by 140%. Fertilization provided tree roots in the
upper soil horizons access to nitrogen during the spring, increasing the concentration of nitrogen
in emerging foliage from 1 to 1.5% of dry weight and free amino acids levels 4-fold. Foliage
102
Scientific Basis for Forest Management in the U.S. Inland West
enriched in amino acids increased shoot growth 3-fold, more than compensating for any
nutritional benefits to insect larvae. The authors suggest that allowing pine forests to be replaced
with fir through fire protection and selective logging has increased the nitrogen demand beyond
that readily supplied in the ponderosa pine/true fir type. They also suggest that fertilizing with
one application of nitrogen at the time of an insect outbreak may reduce mortality and associated
fire hazard through a period o! f up to 5 years, more so that expensive, repeated insecticide
applications.
Whitehead, R.J. & Russo, G.L. (2005). “Beetle-proofed” lodgepole pine stands in interior British Columbia have
less damage from mountain pine beetle. Victoria, Canada: Pacific Forestry Centre, Canadian Forest Service.
Mountain pine beetle activity was examined in untreated and “beetle-proofed” (thinned or
spaced) portions of mature lodgepole pine stands at five sites in central or southeastern British
Columbia. Patch infestations requiring direct control were present in the untreated portions at
all five sites. Number of attacked trees per hectare, mortality due to mountain pine beetle, and
green to red attack ratios were much lower in treated portions. At the four sites where beetle
pressure resulted only from the growth of resident populations during a period of favorable
weather, no infestations requiring treatment developed in beetle-proofed stands. At the fifth site,
extreme beetle pressure that resulted from immigration of beetles from an uncontrolled epidemic
caused unacceptable damage to the beetle-proofed stand. The authors found that proportion
of attacked trees where beetles successfully established and produced brood was high at all
sites, regardless of treatment, suggesting that effect of treatment on ability to resist attack was
not as important as the large reduction in frequency of attacks in beetle-proofed stands.
Wickman, B.E., Mason, R.R., & Paul, H.G. (1992) Thinning and Nitrogen-Fertilization in a Grand Fir Stand
Infested with Western Spruce Budworm .2. Tree Growth-Response. Forest Science, 38, 252-264.
Part two of four-part study testing the effects of thinning and nitrogen fertilization in grand fir
stands in Oregon that had been defoliated by western spruce budworm. Specifically this part
of the study evaluated tree-growth response. The authors found that thinning and fertilization
did significantly improve tree growth. They also found lighter percent defoliation in fertilized
trees, which was unexpected because Part 1 of the study found higher biomass of budworms
in the fertilized stands. In addition, the study found no significant difference in defoliation
between thinned and unthinned stands. They conclude that fertilization could be effective in
this type of stand, providing a viable alternative to insecticides.
Wilson, J.S., Isaac, E.S., & Gara, R.I. (1998) Impacts of mountain pine beetle (Dendroctonus ponderosae) (Col.,
Scolytidae) infestation on future landscape susceptibility to the western spruce budworm (Choristoneura
occidentalis) (Lep., Tortricidae) in north central Washington. Journal of Applied Entomology-Zeitschrift Fur
Angewandte Entomologie, 122, 239-245.
Current and future western spruce budworm hazard was evaluated for a 400 ha (1000 acre)
landscape in north central Washington state using computerized growth and hazard-rating
models. The landscape had recently suffered extensive overstory lodgepole pine mortality due
to a mountain pine beetle infestation. The study attempted to evaluate the impact of this
lodgepole pine mortality on future susceptibility to western spruce budworm outbreaks, using
computer simulations in which overstory lodgepole pine was retained or removed were
compared. Based on the simulations, the authors found that susceptibility to western spruce
budworm attack increases more rapidly and intensely with overstory lodgepole pine mortality.
Annotated Bibliography
103
Additional scenarios included silvicultural treatments to reduce stand density and alter species
composition. Results suggest that a variety of management options are available to reduce
landscape-level western spruce budworm risk.
Wondzell, S.M. (2001) The influence of forest health and protection treatments on erosion and stream
sedimentation in forested watersheds of eastern Oregon and Washington. Northwest Science, 75, 128-140.
Review of studies that have investigated a variety of forest health and protection treatments that
have been proposed for reducing long-term risks to forests from wildfire, insects, and disease.
The review examines the potential effects of these treatments on sediment production in
watersheds, channel forming processes, riparian vegetation, and risks posed to riparian zones.
The studies suggest that the largest risk of accelerated erosion in riparian areas is expected
from ground-disturbing activities during fuels reduction treatments, such as construction of
roads and firebreaks or salvage logging or thinning. Most of the studies reviewed were conducted
at the site or small-watershed scale, so the authors note that the cumulative effects of forest
health and protection treatments imposed across a large region are difficult to assess. The
authors conclude that given the current state of knowledge, dramatically changing forest landuse practices across eastern Oregon and Washington - including the widespread use of
prescribed fires, salvage logging, and mechanical fuel treatments - is a long-term, landscapescale experiment, the cumulative effects of which are unknown.
Youngblood, A., Max, T., & Coe, K. (2004) Stand structure in eastside old-growth ponderosa pine forests of
Oregon and northern California. Forest Ecology and Management, 199, 191-217.
This study measured horizontal and vertical structural attributes in eastside old-growth
ponderosa pine forests, to guide the design of restoration prescriptions. The age, size structure,
and the spatial patterns were investigated in old-growth ponderosa pine forests at three protected
study areas east of the crest of the Cascade Range: Metolius Research Natural Area and Pringle
Butte Research Natural Area in central Oregon and Blacks Mountain Experimental Forest in
northern California. Stands were multi-aged, with as many as 16 cohorts at Metolius and 22
cohorts at Pringle Butte. Mean diameters of these old-growth trees did not differ among the
three study areas; the overall mean was 60.0+or-1.55 cm dbh. Large dead ponderosa pines
were a common feature at all three study areas. A majority of the logs were in an advanced
stage of decomposition, suggesting that they were in place for considerable time. These results
are discussed in the context of reference conditions for restoration of ecosystem health and
ecological integrity in eastside ponderosa pine forests.
Zausen, G.L., Kolb, T.E., Bailey J.D., & Wagner, M.R. 2005. Long-term impacts of stand management on
ponderosa pine physiology and bark beetle abundance in northern Arizona: A replicated landscape study.
Forest Ecology and Management, 218 (1-3), 291-305.
Abstract: Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests in northern Arizona have
degraded due to overgrazing, logging, and fire suppression that accompanied Euro-American
settlement in the late 1800s. Overstocked stands of suppressed trees with low structural diversity
dominate the landscape. These conditions create high risk of catastrophic fires and insect
outbreaks. We investigated long-term effects (8ñ16 years post-treatment) of thinning and
thinning + prescribed burning on ponderosa pine water stress, leaf carbon isotope discrimination
and nitrogen concentration, oleoresin exudation flow, phloem thickness, radial growth, and bark
beetle abundance relative to unmanaged control stands over 2 years of measurement in 12
104
Scientific Basis for Forest Management in the U.S. Inland West
stands replicated across the landscape. Predawn water potential in late June, phloem thickness,
and basal area increment were lower in unmanaged than managed stands. Oleoresin exudation
flow in July was greater in unmanaged and thinned + burn! ed stands than thinned stands, and
greater in a warm year than a cooler year. Leaf nitrogen concentration differed between years,
but not among treatments. Tree competition and water stress were positively correlated, and
tree competition was negatively correlated with radial growth and phloem thickness. Pheromonebaited trap catches of Dendroctonus spp. (D. brevicomis Leconte pooled with D. frontalis
Zimmerman) were higher in unmanaged than managed stands, whereas catches of Ips spp. did
not differ among treatments. We conclude that thinning with and without prescribed burning can
have long-term effects on ponderosa pine water stress, growth, phloem thickness, resin flow, and
bark beetle abundance. Low levels of tree mortality from bark beetles at our study sites suggest
remarkable resistance of ponderosa pine in mid-elevation forests in northern Arizona, even at
high tree densities.
Yale University’s Global Institute of Sustainable Forestry
105
Interior Douglas-fir series
USFS Region 6
Ponderosa pine series /
medium to high site
Ponderosa pine series / low
site
DNR managed lands in WA,
including eastern WA
Washington DNR 2005
COMMENTS
13 tpa >= 21" and >= 150 years; Hopkins et al. 1992
3 tpa >= 31" dbh and > = 200
years
yes; in larger size class
2
3-6 tpa >= 14"
presence of decadent trees
canopy layers
standing dead trees
These interim definitions were intended to be used
until more rigorous scientific data were developed
Williams et al. 1992
presence of large old trees
2
3-6 per acres at least 14" dbh
canopy layers
standing dead trees
12" diameter / 2 pieces per acre
down logs
yes; in larger size class
1
1 per ac (2.5 per ha) 12" (30cm)
or greater
canopy layers
standing dead trees
presence of decadent trees
2 per ac or 5 per ha
presence of decadent trees
10 tpa >= 21" and >= 150 years;
2 tpa > = 31" and > = 200 years
trees s/b > 150 years old
presence of old trees
presence of large old trees
8 tpa >= 21" (20 tph >= 53 cm)
nothing specified - see comments Committee tasked with coming up with OG
definitions for DNR managed lands were "unable
to make significant progress on characterizing or
defining old-growth forest conditions…" pg. 15
They also found that the USFS definitions "had
almost no value in recognizing old-growth
conditions on the ground." pg. 15
THRESHOLDS
presence of large trees
presence of large old trees
STAND TYPE/STUDY LOCATION CRITERIA
AUTHOR
Old Growth Characterization in Inland Northwest Forests: Synopsis of Scientific Studies on Definition of Old Growth
106
Mosseler et al. 2003
N/A
2
1 per acre >= 14" dbh
5 pieces per acre >= 12" diameter
canopy layers
standing dead trees
down logs
300+ years
Some trees close to maximum
longevity
Minimal evidence of human
disturbance
Catastrophic disturbances recur less
frequently than the maximum
longevity of dominant tree species
Disturbance regime characterized by
gap dynamics
Presence of long-lived shade
tolerant tree species
Natural regeneration of dominant
tree species in gaps or on decaying
logs
Presence of CWD in varying states
of decay
~ 150+ years
Average age of dominant species
approaching half the maximum
longevity for species
Uneven aged or multi cohort
yes
presence of decadent trees
15 tpa >= 21" dbh
5 pieces per acre >= 12" diameter
down logs
Grand fir / white fir series - high presence of large old trees
sites
2
1 per ac >= 14" dbh
canopy layers
standing dead trees
10 tpa >= 21"
yes
Grand fir / white fir series - low presence of large old trees
and medium sites
USFS Region 6
THRESHOLDS
presence of decadent trees
STAND TYPE/STUDY LOCATION CRITERIA
AUTHOR
A general definition for Canada
Hopkins et al. 1992
COMMENTS
Old Growth Characterization in Inland Northwest Forests: Synopsis of Scientific Studies on Definition of Old Growth
107
Ponderosa pine forests of
eastern OR and northern CA
Interior BC forests
McKinnon and Vold 1998
THRESHOLDS
COMMENTS
9.0 (+/- 0.97) per ha; mean dbh
61.7 with a modal distribution
ranging from 25-125 cm
~ 47 logs per ha large end
diameter 37.6, mean length4.2 m;
cumulative length 512.9 +/78.12m
Aggregated or clumped with
clumps > 22 m in diameter; or
randomly distributed
Snags
CWD
Spatial pattern of upper canopy
Based on a study of three old ponderosa pine
stands
> 140 years for species other
An inventory of old growth forests in British
than lodgepole pine; > 120 years Columbia
for lodgepole pine and deciduous
forests
50 (+/- 3.5) trees per ha; mean
diameter 60(+/- 1.55 cm dbh;
modal distribution ranging from
25-125 cm dbh
Density upper canopy trees
Age
> 3 age classes in upper canopy;
youngest age class dating from
before 1900
Stand age
Forest that meets a threshold
Can include one or more of the
General definitions and concepts
determined by some political and(or) following: stand age; minimum
scientific process
age of trees (absolute or relative
to their potential maximum);
minimum size of trees (either
absolute or relative to maximum
potential for the site); stage of
development and succession:
degree of naturalness, such as
lack of past management
STAND TYPE/STUDY LOCATION CRITERIA
Youngblood et al. 2004
Frelich and Reich 2003
AUTHOR
Old Growth Characterization in Inland Northwest Forests: Synopsis of Scientific Studies on Definition of Old Growth
108
Estimated date of last fire more
than 20 years older than in
surrounding plots/stands.
Single cohort of lodgepole pine ~
335 years old; spruce ranging in
age from 295-335 years;
subalpine fir from 39 to 335 years
Depending on forest type,
Concludes that a single, precise definition of old
minimum age of stand 150 - 200 growth is neither possible or desirable. Usefulness
years
of a definition depends on purpose for which it was
designed. Old growth forests vary considerably
within and among forest types and there is
considerable overlap between developmental
stages. Authors propose that forests where gap
dynamics predominate have attained functional old
growth status.
Disturbance history
Subalpine fir forests in southern Age
interior BC
Interior BC forests
Antos and Parish 2002
Wells et al. 1998
Age
Canopy closure > or = 60% AND
at least 3 canopy strata contain
grand fir, subalpine fir, western
hemlock, and/or Engelmann
spruce for unaltered stands. In
previously logged stands canopy
closure > or = 40% AND at least
2 canopy strata with the
abovementioned species.
Structure
The thresholds and criteria were elucidated from
reconstruction of a single stand and were not
developed nor intended for use in identifying old
growth. The paper also reports on spatial
arrangement of live and dead trees.
Presence of grand fir, western
Criteria and thresholds were used to identify fire
hemlock, or Engelmann spruce > refugia and not necessarily old growth
or = 130 years in GF series;
presence of subalpine fir or
Engelmann spruce > or = 150
years in SAF series (aged at
breast height)
Age
Wenatchee Mountains, WA
Camp et al. 1997
COMMENTS
THRESHOLDS
STAND TYPE/STUDY LOCATION CRITERIA
AUTHOR
Old Growth Characterization in Inland Northwest Forests: Synopsis of Scientific Studies on Definition of Old Growth
109
1993
2006
1995
2004
2003
2004
2000
2006
Akay et al.
Beschta et al.
Beschta et al.
Brown et al.
Brown et al.
Carroll et al.
Donato et al.
Date
Agee
Authors
Science
Conservation Biology
Opinion / Review of
literature
truncated field-based
research (published prior
to completion of study)
from Biscuit Fire in OR
Rocky Mountain Research
Station
modeling approach
USDA Forest Service
There is a wide range in acceptable amounts of CWD and this is
based on site and landscape considerations: burn severity, desired
future condition for forest, restoration objectives, and desired
structural diversity. Quantities of CWD change over time, vary with
respect to fire severity and post-fire management as well as pre-fire
conditions.
Conservation Biology
Opinion / Review of
literature
USFS GTR PNW
Discusses various post-fire management practices (salvage,
seeding, etc.) from an ecological perspective and describes postfire restoration considerations wrt soils, wildlife, etc. Primarily antisalvage because they contend that salvage is primarily focusd on
taking the largest trees.
Conclusions of salvage effect on regeneration based on 1 year and
only addresses conifer regeneration
Social assessment of the 1994 fires in Wenatchee, WA.
Documented the reactions of local residents and identified the
diversity of strong beliefs and values about fire and forest
management held by these residents. The take home message is
that these beliefs and values are likely more influential than any
scientific information.
Proposes that low thinning is the most appropriate kind of treatment
for making forests resistant to fire. Leaving large fire-resistant trees
is also necessary.
This white paper was written in response to the 1994 salvage rider
that eliminated NEPA requirement to implement salvage after major
catastrophic fires that year.
Unpublished Work
Opinion / Review of
literature
Calculates value of timber as a function of time since death with
helicopter yarding as the preferred method of extraction
A widely used and well-researched book on fire and fire regimes in
the western US - especially the Pacific Northwest.
Notes
Western Journal of Applied
Forestry
Outlet (P=peer-reviewed)
model parametized with
data from northern CA
book
Research Type
Post-Fire Salvage Logging Papers
110
Date
2003
1988
2001
2005
1999
2006
1997
Authors
Dwire and Kauffman
Hadfield
Haggard and Gaines
Hanson and Stuart
Ice and Beschta
Jain
Jurgensen et al.
Opinion / Review of
literature
Opinion given during a
phone conversation with
Jennifer K.
Opinion of two scientists
with very different
perspectives
Field-based from NW CA
Field-based study from
eastern Cascades Mts.
WA
Forest Ecol. And Mgmt.
Opinion / Review of
literature
Compared to unsalvaged stands, removal of snags and postsalvage broadcast burning altered plant composition and increased
the influence of the fire-created edge environment on the adjacent
unburned forest.
Cavity nesting birds were primarily found in stands with high or
medium snag densities following fire; fewer were found in stands
with low snag densities. Stands with medium densities of snags
were most often used. The number of snags in stands classes as
low, medium, and high density varied greatly and the species
composition of snags may also have been a factor, although that
was not accounted for in the study.
Notes
Asserts that additional data are needed to understand interactions
between fire and riparian ecosystems to prescribe ecologically
sound rehabilitation projects following fire. (Do little or nothing until
we know more approach)
Forest Science
The paper referenced many past studies of the impacts of timber
harvesting on soil organic matter, nitrogen, and soil productivity.
Authors stress that management should consider historical soil
organic matter levels and define these where necessary. Harvesting
impacts on soils need to be addressed when developing fuels
reduction treatments or post-fire salvage harvests. Potential for fire
must be balanced against need for woody debris in fire-prone forest
ecosystems.
Jain is a research forester with the USFS in Moscow, ID
Two forest hydrologists differ with respect to effects of post-fire
management. If nothing else, this paper highlights Carroll's
National Council for Air and
assertion that beliefs and values are as important as scientific
Stream Improvement, Inc.
evidence in framing the answers to questions about the desire,
efficacy, and impacts of salvage.
Forest Ecol. And Mgmt.
Northwest Science
Northwest Environmental
Journal
Outlet (P=peer-reviewed)
Research Type
Post-Fire Salvage Logging Papers
111
2006
2004
2001
2003
1990
2003
2003
2000
2000
Lindenmayer
McIver and Starr
McIver et al.
McNabb and
Swanson
Minshall
Rieman et al.
Robichaud
Robichaud et al.
Date
Kolb
Authors
Notes
Forest Ecol. And Mgmt.
Forest Ecol. And Mgmt.
Opinion / Review of
literature
Opinion / Review of
literature based on Interior
Columbia Basin
Assessment
Journal of Hydrology
USDA Forest Service
Oregon State University
Western Journal of Applied
Forestry
Western Journal of Applied
Forestry
Science
"Significant questions regarding the influence of fire on aquatic
ecosystems, changing fire regimes, and the effects of fire-related
management remain unresolved and contribute to the uncertainty."
Proposes that aquatic ecosystems and terrestrial ecosystems must
be jointly considered in fire-related (pre and post) management.
Fires are not likely to significantly impact stream benthic
macroinvertebrates but post-fire logging can be potentially harmful.
Author asserts that no more than 25% of the merchantable timber
should be removed in salvage operations "unless contradictory
information is available." The 25% figure is nowhere substantiated
and many of the assertions are based on "personal
observation."+E10
Discusses effects of fire - especially Rx fire - on soil erosion
Harvesting increased fine fuels to some extent but removal of larger
fuels changed fuel model to one that would burn less severely and
would be less likely to crown out.
"Salvage harvesting activities undermine many of the ecosystem
benefits of major disturbances."
Fire severity and forest community type affect plant recolonization;
initial recovery and rate of recovery is highly variable; in MT post-fire
veg. recovery generally occurs within the first growing season and
increases at a much slower rate; there are many sources of
Testimony before Congress
recolonizing vegetation; salvaged sites showed similar recovery to
unsalvaged sites; conifer regeneration was correlated with
occurrence of seed producing mature trees and prevelance of
shade from either surviving trees or northerly aspects.
Outlet (P=peer-reviewed)
book chapter
field based study from NE
OR
Opinion / Review of
literature
Based on as yet
unpublished research
Research Type
Post-Fire Salvage Logging Papers
112
2002
2000
2004
2003
1993
Schellhaas et al.
Sessions et al.
Sessions et al.
Stuart et al.
Date
Saab et al.
Authors
Forest Science
Oregon State University
College of Forestry
Opinion / Review of
literature
Field-based from NW CA
Journal of Forestry
USFS GTR- PSW
field based study from SW
ID
database assessment
Outlet (P=peer-reviewed)
Research Type
Post-Fire Salvage Logging Papers
Post-fire treatments were examined in early successional and old
groth Douglas-fir / hardwood forests. Study focus was regeneration
of timber species. Results concluded that hardwoods inhibited DF
establishment on salvaged sites and brush inhibited DF
establishment on unsalvaged sites.
Salvage is proposed as effective for restoring mature conifer forests
on the landscape burned by the Biscuit Fire. Salvage will reduce fuel
loads, reduce ancillary tree death from insect attack, and hasten
recovery. Socially it provides a temporary source of extra revenue.
Basically takes a "wise use" utilitarian approach to post-fire
management.
See below.
Showed that different amounts and sizes of snags were selected by
different cavity nesting birds - from stands with many small snags to
stands with few large snags. Take-home message is that one
management strategy will not be sufficient to insure adequate
habitat for all species and that pre-burn vegetation classification can
be useful in developing post-fire management options.
Notes
113
Date
1995
2001
2004
2001
2001
2003
2000
1997
2001
1999
1999
2001
2005
Authors
Cole and Koch
Hartsough et al.
Ager et al.
Hemstrom
Hemstrom et al.
Hessburg and Agee
Hessburg et al.
Jurgensen et al.
Lehmkuhl et al.
Murphy et al.
Powell
Quigley et al.
Reynolds and
Hessburg
FOREST HEALTH
Cost models for 6 different harvesting systems
Review of past spacing studies and economic recovery and utilization to
inform management options
Notes
Forest Ecol. And Mgmt.
(P)
Forest Ecol. And Mgmt. Found mid seral forests more prevalent than in the past and old forest less
(P)
so (especially old seral forests)
Review of methods to model conifer mortality from I & D and how to
incorporate these into landscape planning models
Discussion of vegetation patterns, disturbances, and forest health for a
Northwest Science (P)
special issue of the journal
USFS GTR
Forest Products J.
USFS GTR
Outlet (P = peerreviewed)
Host
Northwest Science (P) Overview for special issue of journal
USFS GTR
various
Implementation guide for managers using Cochran's 1994 research note on
various
stocking levels for Blue, Ochoco, and Wallowa Mountains forests;
various
interior
Columbia
Basin
interior
Columbia
Basin
various
E OR & WA
ID
Growth of advanced LP regeneration best when entire overstory removed;
shorter trees (<1.6m) responded better than taller trees to release;
Forest Ecol. And Mgmt. damaged trees much less able to respond to release; advance regeneration
(P)
shortens rotation but damage must be minimized; advance regeneration or
retention of overstory necessary on extremely harsh sites to ameliorate site
conditions.
general forest
health
general forest
health
stocking
levels
response of
regen to OS
removal
general forest
health
general forest
health
general forest
health
general forest
health
general forest
health
interior
Columbia
Basin
LLP
multiple
comparison
of harvesting
methods
Other
Forest Ecol. And Mgmt. Model not verified; tracked changes in ungulate habitat with increases over
ungulates
(P)
the next century predicted.
interior
Columbia
Basin
interior
Columbia
Basin
interior
Columbia
Basin
inland west
OR (Blue
Mountains)
across range LLP
Location
impacts of
harvesting on
SOM
Maintenance of soil organic matter critical to maintaining forest health and
productivity and is especially critical and difficult on the driest sites; may
initially increase fire, insect, disease risk; risk can be somwhat mitigated
through management;
Insects
MPB
Organism
inland west
Forest Science (P)
Remote sensing
and modeling
(Columbia River Forest Ecol. And Mgmt. Uses CRB assessment data to develop a decision support tool that
Basin Assessment)
(P)
identifies watersheds most out of historical vegetation conditions.
- decision support
systems
Review and
synthesis
Implementation
guide for managers
Field-based
research
Modeling
Review and
synthesis
Remote sensing
Shifts from earlier to later seral stages; decline in old seral and late seral
and modeling
Forest Ecol. And Mgmt.
forests; decline in initiating phase of forest development; loss of medium to
(Columbia River
(P)
large trees; increase in shade tolerant species
Basin Assessment)
Review and history
Modeling
Review and
synthesis
Review and
synthesis
Modeling
Synthesis
Research Type
Insects and their Management Papers
114
2001
1989
1994
2004
2005
2001a
2001b
2001
2004
Stuart et al.
Wagner
Youngblood et al.
Black
Bull and Wales
Bull and Wales
Bull et al.
Bunnell et al.
Date
Starr et al.
Authors
Notes
Organism
SALVAGE LOGGING
Looks at stand structure of 3 old growth PP forests to inform restoration; old
trees were randomly distributed in one stand, clumped in the other two
Forest Ecol. And Mgmt. stands; stands had multiple cohorts of old trees; study areas probably were
PP
(P)
not heavily influenced by Native Americans prior to European settlement;
excellent discussion that ties stand structures found here to others in the
Inland west and discusses similarities and differences.
Journal of Forestry
Looks at methods to reduce competiton from competing vegetation on
forest stands
Development of a framework to identify knowledge gaps and linkages
Northwest Science (P) among factors influencing forest health; management options were all
identified as elements having critical knowledge gaps
LP reproduction in an old self-perpetuating LP forest in south central OR
limited by soil moisture; shading by overstory provided relief from excessive
Can. J. For. Res. (P)
LPP
evapotranspiration, heat, and frost; extreme site - not representative of LP
forests throughout the inland West
Outlet (P = peerreviewed)
north central
OR
south central
OR
interior
Columbia
Basin
Location
Review
Review
Review
Similar to above but for birds of conservation interest; management has
some benefits and some drawbacks depending on species.
Natural Resources
Canada
carnivores
birds
E OR & WA
E OR & WA
Extensive review of literature documenting the effects of salvage logging on
vertebrates. Focus is the interior BB outbreak in LP dominated forests.
vertebrates interior BC
Excellent summary of stand and landscape implementation of salvage to
mitigate negative effects on vertebrate populations.
Northwest Science (P) Similar to above but for forest carnivores; management mostly detrimental
Northwest Science (P)
"Little or no evidence to support assumption that increased logging will
make forests less vulnerable to insect infestations." Simplification of forests
from fire suppression and logging may increase risk of insect outbreaks.
Xerces Society
Forest with diverse tree species and age classes are less likely to develop
publication supported by large insect outbreaks. No evidence that logging can control an outbreak of
Synthesis of
grants from Bullitt and bark beetles or defoliators once an outbreak has started. Evidence that
Insects
western US
reviewed literature
other foundations that thinning can control bark beetles is mixed. While the tone of the paper is
are against management anti logging, it does bring up many important functional roles of insects that
are often ignored. The paper also summarizes many research papers in an
annotated bibliography. A good paper that counters some of the reviews
from USFS scientists.
Some amphibians of conservation concern could be negatively impacted by
management activities like harvesting (removal of canopy impacts
amphibians E OR & WA
Review
Northwest Science (P)
microclimate), Rx fire (kills outright and removes habitat), pesticide
spraying. For special issue of journal.
Field-based
research
Integration of old
knowledge to new
uses
Field-based
research
Delphic process
based influence
diagramming
Research Type
Insects and their Management Papers
stand
structure
integrated
forest
vegetation
management
regeneration
general forest
health
Other
effects of
disturbance
on organism
effects of
disturbance
on organism
effect of
salvage
logging
following
MPB
effects of
disturbance
on organism
the person
who wrote
this might be
various
a good
person for the
panel
Host
115
2002
2004
2001
2001
2004
2005
2005
1996
2000
Eng
Howell
Hughes and Drever
Lindenmayer et al.
McLeod and Bunnell
Oester and
Emmingham
Parry et al.
Radeloff et al.
Date
Camp
Authors
Western J. Applied
Forestry (P)
USFS GTR
Field-based
research and
subsequent
modeling
Field-based
research with
literature review
Remote sensing
Symposium on MPB
held in Kelowna, BC
Annotated
Bibliography
NW
Wisconsin
DFB / WSB E oR
E OR
Thinning to carefully prescribed stocking levels increases volume growth
per tree and reduces beetle and fire threat. Study followed tree mortality for
PP
13 years after treatments to assess threats from beetles (Ips and MPB).
This was a study in PP stands on private land.
Study documented the effects of time since death on the usable product
volume and value of beetle killed DF and GF trees in the Blue Mts. GF
trees deteriorated less quickly than DF - a surprising outcome contrary to
popular belief.
interior BC
interior BC
Recent and relevant literature directly related to managing large outbreaks
of MPB are limited with respect to wildlife and virtually non-existent with
respect to fish.
Suggests formulating salvage policies prior to disturbances to ensure
ecological considerations are fully addressed.
Jack pine forests in Wisconsin - outside study area. Did show that one areasensitive, open habitat species thrived in large openings created by
slavaging forests killed by pine budworm defoliation. Discusses differences
Ecological Applications
in landscape pattern of opening created by fire verse salvage and
ESB
(P)
addresses impacts of logging on soil nutrients, invertebrates, etc.
Concludes that salvage harvesting should consider larger landscape issues
related to vegetation patterns.
Science (P)
Suzuki Foundation;
Forest Watch of BC;
Canadian Parks and
Wilderness
Conclude that the current BB outbreak in BC is a socio-economic challenge
and not an ecological crisis. Asserts the natural role of BB in forested
ecosystems and concludes management cannot control outbreak but may
have negative ecological consequences. Discusses socio-economic impact
of management as well as ecological and concludes that increases in the
allowable cut may promote economic unsustainability. Promotes an
adaptive approach to mountain pine beetle management and highlights
need for more research on beetle impacts.
E OR & WA
Opinion
Review
Review
NE WA
Location
Review of effects of fire, insects, diseases, management, and other
disturbances on fish populations and habitats; most effects moderate within
Northwest Science (P) a decade; effects from severe fires and floods take longer to recover from fish
(centuries in some instances); management is best implemented outside
critical areas and monitored for impacts
Organism
interior BC
Study documenting wounding of residual trees following thinning to reduce
fire and insect risk in mixed conifer stands. Cut to length less damaging
than whole tree harvest and skyline yarding less damaging than forwarder
yarding. Silvicultural Rx, season of harvest may affect damage levels.
Notes
Provides recommendations for ensuring all forest values are conserved
BC Ministry of Forests
during large-scale salvage of BB killed forests in the interior of BC. Values
Tecchnical Report
considered include hydrological, soils, fire risk and the WUI, and habitat.
Western J. Applied
Forestry (P)
Field-based
research
Review and
synthesis
Outlet (P = peerreviewed)
Research Type
Insects and their Management Papers
policy
discussion on
salvage
effects of
salvage on
ecosystem
effects of
disturbance
on organism
forest
stewardship
and salvage
logging
damage to
residual trees
from different
harvesting
systems
Other
thinning
options
geared to
family forest
owners
deterioration
and recovery
DF / GF of timber
following
outbreaks
Host
116
2001
2001
1996
2005
1994
2002
2001
1996
1995
2000
Wondzell
Wilderness Society
(Gorte and Draper)
Barbour et al.
Filip
Filip et al
Hayes and
Ragenovich
Scott
Torgersen and Bull
Muzika and Liebhold
Date
Wales
Authors
Review and
synthesis
Field-based
research
Implementation
guide for managers
Review and
synthesis
Field-based
experiment
(treatments)
Field-based
research
GIS / FIA / CVS synthesis of
existing data
Review and
assessment
Review
Review
Research Type
Outlet (P = peerreviewed)
Notes
Written to assist foresters with assessing stand risk to loss from insects
and thus candidates for salvage; 8 factors are considered and a decision
system for evaluation is provided.
insects
IAS
multiple
multiple
multiple
esp. fire
Organism
Northwest Science (P)
Discusses the relationships among ant species and characteristics of fallen
ants
logs inhabited by different ant species.
Theoretical foundation of silvicultural approaches to managing defoliating
Agricultural and Forest insects are largely based on observation and correlation, not empirical or
defoliators
Entomology (P)
experimental evidence (which, when it does exist has yielded inconsistent
results).
USFS Report
Very generalized with predictable conclusions - focus treatments in high
Forest Ecol. And Mgmt. high priority areas; lack of merchantable timber will make some areas less
(P)
desirable to treat unless some high value trees are included; best to spread
treatments across a variety of ownerships.
Grand fir that established as a result of fire suppression is being killed by a
variety of agents - bark beetles, defoliators, and root diseases that will
decrease the % of fir and increase soil organic matter in the absence of fire.
Northwest Science (P)
Forest health will decline as grand fir and other fir species increase;
silvicultural treatments can mitigate if less susceptible species are favored
for retention.
Fertilization may have increased health of budworms through increasing N
Western J. Applied For. content of needles. No sig. effects of fertilization on GF or WL mortality,
diameter increment, vigor, or live crown ratios. No sig. impact on larch DM
(P)
severity.
Prevention is the key to invasive species threats to forest health; treatments
Northwest Science (P) that may control or mitigate problems caused by native species will likely
not be effective against ivasive alien species.
INSECT OUTBREAKS
Largest risk of accelerated erosion is expected from ground-disturbing
activities during fule reduction treatments or salvage logging. Most of the
Northwest Science (P)
studies reviewed were from site or small watershed studies. There is a lack
of larger-scale research.
Undertaken as a result of the 1995 salvage rider to examine salvage
logging in National Forests. Salvage is increasing as a management
practice as live timber volume harvesting has declined. 80% of salvage
activity during the 1990s was in the northern Rocky Mountains, the Pacific
The Wilderness Society Northwest, and California. Points out some exemptions and incentives for
using salvage as a harvesting mechanism. Refutes notion that tree
mortality information (at what scale?) suggests unhealthy forest conditions
and quotes Oliver and Larson regarding high natural mortality during stem
exclusion phase of forest development.
For special issue of journal. Looks at what is known about impacts of fire,
Northwest Science (P) salvage, and insects disease on riparian habitats. Concludes that salvage
may negatively impact species that require dead and dying trees.
Insects and their Management Papers
North
America
NE OR
NE OR & SE
WA (Blue
Mountains)
E OR & WA
NE OR
Central OR
NE OR
western US
E OR & WA
E OR & WA
Location
Host
ecological,
ecconomic,
and legal
assessment
of salvage
logging and
the salvage
rider
sedimentation
and erosion
riparian
habitats
Other
117
1991
1994
2001
2005
2001
2001
2004
1999
Shepherd
Torgersen
Fayt et al.
Hayes and
Daterman
Hindmarch and Reid
Safranyik et al.
Safranyik et al.
Date
Ravlin
Authors
Breeding habitat for secondary bark beetles greater in thinned stands of LP
as opposed to unthinned stands but returned to background levels within 3
years. Thinned stands have more and greater diversity of bark beetle
species over the 3 year period of the study. Microclimate may have
increased bark beetle numbers and diversity. (This study contrasts with
BBs
many earlier studies that suggest thinning decreases beetle numbers).
Authors suggest this is because earlier studies focused only on
Dendroctonus species and used tree mortality (not specific counts of
trapped beetles) as the measure of beetle numbers. Greater tree vigor in
thinned stands may offset greater numbers of insects.
Review and
synthesis
Field-based
research
Field-based
research
Field-based
research
E OR & WA
Pesticides, attractants, anti-aggregation pheremones, and trap trees are
useful in specific applications. Salvage or sanitation harvests of wind or fire
Northwest Science (P) damaged trees can prevent bark beetle population buildups if done
BBs
promptly. Integration of these methods with Rx fire and silviculture has
been recommended (in the reviewed literature).
Found that thinning (spacing) LP increased bark beetle numbers but not
number of species but that this increase lasted only 3 years. Beetle
diversity was not influenced by site or treatment. Increase in numbers
reflected greater amount of breeding material (slash etc.). Stand conditions
Forest Ecol. And Mgmt. affect host seeking by bark beetles; secondary bark beetles may
BBs
(P)
predispose attacked trees to co-attack by endemic levels of mountain pine
beetles. Care in avoiding injury to residual trees is important in thinning
because injured trees may be attacked by secondary bark beetles in the
two years following thinning. Attack success, however, will be less than in
unthinned stands.
The Canadian
Similar results to Safranyik et al. 2004 and appears to be essentially the
BBs
Entomologist (P)
same study
SE BC
SE BC
Alberta
over range
Circumstantial evidence that supports role of woodpeckers on population
Forest Ecol. And Mgmt. dynamics of spruce bark beetles. Regulation of BBs by woodpeckers
SBB
(P)
depends simultaneously on density and metabolic requirements of the birds
and on the abundance, availability, and caloric content of the beetles.
Review and
synthesis
Canadian J. Forest
Research (P)
E OR & WA
Review and
synthesis
defoliators
BC
Location
Forest Ecol. And Mgmt. Review of management strategies tied to whether outbreaks of defoliators
(P)
are fast cycle or sustained.
Organism
North
America
Notes
Forest Ecol. And Mgmt. No new information; monitoring and decision support based on pre-existing
defoliators
(P)
knowledge.
Outlet (P = peerreviewed)
Suppression projects (primarily spraying) against defoliators have
prevented some tree mortality and growth loss, but have been ineffective in
Northwest Science (P) changing outbreak behavior of defoliating insects. Key to prevention of
defoliators
outbreaks is silvicultural treatments to promote tree species diversity,
diverse stand structures across landscapes, and moderate stocking levels.
Monitoring and
decision support
system
development
Review and
synthesis
Research Type
Insects and their Management Papers
LPP
LPP
LPP
Host
Other
118
2005
1998
1994
1996
1993
2000
Amman and Logan
Bartos and Booth
Bentz et al.
Bentz et al.
Chojnacky et al.
Date
Zausen et al.
Authors
Field-based
research and
modeling
USDAFS RMRS
Research Paper
Future work on rating bark-beetle impact should consider more than stand
characteristics; increasing mountain pine beetle attacks is correlated with
increasing SDI , but high SDI may not be a significant factor for outbreak
initiation. Factors independent of density may initially bring beetles into a
MPB
stand, but once there the beetles seek out dense pockets within the stand.
No method based on stand characteristics alone is likely to rate the risk of
beetle entry into a given stand.
MPB
MPB
Field-based
research
USDA Forest Service
Tree density affects stand micro-climates which in turn affect MPB
Intermountain Research
behavior.
Station
MPB may switch to a new focus tree prior to the original focus tree being
fully colonized. Inconsistent results using pheromones in management
RMRS Research Paper
attest to insufficient understanding of full complement of MPB chemical
ecology.
Four hazard/risk assessments for MPB were evaluated using data from 105
stands; none of the four adequately predicted mountain pine beetle
mortality in the tested stands. Reasons may be 1) confusion in terminology
Forest Ecol. And Mgmt.
used; 2) no consideration of the population phase of the beetle (endemic or MPB
(P)
epidemic) during development of the rating system; 3) need to include more
information on mountain pine beetle population dynamics; 4) need to
include spatial nature of beetle populations and stand conditions
Field-based
research
Field-based
research
AZ CO UT
northern MT
ID
WY
over range
Review and
synthesis
Location
Compelling body of evidence suggests thinning deters MPB infestations,
mechanistic pathways by which these effects are expressed remain
obscure. Needed is research on how the physical environment (microclimate) affects phermone interactions that lead to switching attack to
adjacent trees and how beetles respond to pheremone plumes. Need to be
American Entomologist able to predict landscape-level impacts of silvicultural treatments over
MPB
(P)
longer timeframes; no longer sufficient to measure impact of silv. Rx on
stand susceptibility and risk to MPB depredation. After nearly 60 years of
attempts to control MPB through silviculture we need to realize we can't
eliminate the beetle from western forests and must develop the ecological
understanding to incorporate natural disturbance events within attainable
and sustainable forest management objectives.
Organism
northern AZ
Notes
Field-based
research
Outlet (P = peerreviewed)
Thinning PP stands decreased water stress compared to untreated stands,
but contrary to expectations also decreased resin flow (one method trees
have to pitch out bark beetles). The authors suggest that effects of thinning
Forest Ecol. And Mgmt. on resin production cannot be generalized without considering tree size and
BBs
(P)
the intensity and duration of thinnings. Theoretically, trees should allocate
more carbon for growth under optimum conditions and more for defense
(resin production) under moderately stressful conditions - this study would
lend credence to this hypothesis.
Research Type
Insects and their Management Papers
PP
LPP
LPP
LPP
PP & LPP
PP
Host
Other
119
Date
1995
2006
2004
2002
2005
2001
1991
2004
2005
Authors
Cochran and Barrett
Dymond et al.
Elkin and Reid
Johnstone
Li et al.
Logan and Powell
Mitchell and Preisler
Negron and Popp
Oester and
Emmingham
Field based
research
Field based
research
Modeling
Empirical model
Simulation
Field-based
experiment
(treatments)
Field-based
experiment
(treatments)
Remote sensing
USDAFS PNW
Research Paper
Field-based
research
Organism
Confirms other studies in PP stands that competition from smaller trees
reduces growth of larger trees in even-aged stands. Reduced vigor of larger
trees increases susceptibility to MPB. Other research papers authored by MPB
Cochran with different co-authors also suggest early spacing control to
increase diameter growth and decrease risk to beetle attack.
Notes
MPB
Looked at MPB success in high elevation whitebark pine forests in the
American Entomologist
Rocky Mountains under a scenario of warming climate. Not particularly
(P)
relevant.
Big trees important to outbreaks beyond simply generating beetles and
many trees are colonized because of proximity to other trees under attack.
Model was developed using assumptions from Geiszler and Gara - that p of
attack is related to diameter of tree and distance from previously attacked
Forest Science (P)
tree and an initial random flight. Big trees are the ones colonized by
pioneers and attract beetles to the stand. (Is this really true or how the
model worked? Paper seems to suggest that w/o big trees there will be no
outbreaks.)
Used CART - SDI (basal area) was most important split between infested
and non-infested stands. Environmental characteristics weren't in model Forest Ecol. And Mgmt.
only stand characteristics and tree characteristics (such as crown class).
(P)
Dominant and co-dominant trees were most likely to be attacked in infested
stands.
Thinning to carefully prescribed stocking levels can increase volume growth
Western J. Applied For.
per tree and maintain reasonable stand value growth even though cubic
(P)
volume growth is diminished.
Host
LPP
LPP
hypothetical
forest in
central BC
CO
E OR
PP
PP
LPP
high elevation WBP
LPP
SE BC
BC (Banff
and Kootnay LPP
NPs)
central BC
NE OR & SE
WA (Blue
PP
Mountains)
Location
MPB, WPB E OR
MPB
MPB
MPB
Ecological Complexity Outputs of model based on assumption that LP stands became susceptible
MPB
(P)
to MPB attack at about 60-80 years of age;
Long term (56 year) study indicates that trees in the most heavily thinned
BC Ministry of Forests - stands were better able to survive mountain pine beetle attacks. Also
Science Program
showed that more diverse stands (species) were less likely to sustain
Working Paper
mortality from mountain pine beetle. Variation in measurement methods
over the duration of the study make it difficult to statistically analyze data.
Environmental
Entomology
Beetles did not preferentially attack fire damaged trees and beetle
reproductive success was not affected by fire damage. At low attack levels,
beetles were more able to overcome defenses of fire damaged trees; at
MPB
high attack levels trees were successfully overcome no matter the
treatment. Fire damage only matters where attacks are at low levels.
Evaluated a risk rating system and compare ratings with remotely sensed
Western J. Applied For. data from infested stands. Found tendency for stands rated highly
MPB
(P)
susceptible to be infested, but some low susceptibility stands were infested
and some highly susceptible stands were not.
Outlet (P = peerreviewed)
Research Type
Insects and their Management Papers
Other
120
1996
1993
2001
2005
1992
2003
1992
1992
1992
1998
2004
Preisler and Mitchell
Safranyik et al.
Whitehead and
Russo
Filip et al
Hummel and Agee
Mason et al.
Waring et al.
Wickman et al.
Wilson et al.
Dodds et al.
Date
Olsen et al.
Authors
Forest Science (P)
Field based
research
GIS / survey data
Removing LP overstory increased susceptibility of understory fir to WSB.
Thinning for WSB control somewhat increased WSB dry mass. Value of
thinning WSB infested forests as a pest control not supported; decision to
thin must be based on tree and stand productivity.
Conversion of pine forests to fir forests because of fire suppression has
increased the N demand beyond what is readily supplied. Fertilizing with
one application of N at the time of a WSB outbreak may reduce mortality
and associated fire risk for up to 5 years. Thinning may increase % of fir,
thus increasing susceptibility to insects.
Where maintaining fir on pine sites is desired over the short term, N
fertilizing might be more effective than spraying to control WSB.
MPB / WSB
WSB
WSB
WSB
With increasing DFB populations, higher tree mortality in high risk (sensu
Western J. Applied For. Randall and Tensmeyer 1999 risk rating system) areas; during endemic
DFB
populations, DFB-caused mortality mostly in stands with recent disturbance
(P)
(brood material available).
Journal of Applied
Entomology (P)
Forest Science (P)
Field based
research
Modeling
Forest Science (P)
Field based
research
WSB
GF
GF
GF
DF / GF
DF
LPP
ID
DF
WA
LLP / DF
(northcentral)
E OR
E OR
E OR
E WA
Forest Science (P)
Field based
research
Northwest Science (P) WSB mortality did not increase the potential for fire severity in study area.
E OR & WA
Study done following defoliation by WSB. Supports use of thinning and
fertilizing to improve grand fir growth and vigor and reduce losses from
stem decay.
Natural Resources
Canada Information
Report
Field based
research
Field based
research
BC (south
and central)
Where beetle pressure resulted from growth of resident populations during
a period of favorable weather, beetle-proofed stands were not attacked.
Where beetle pressure resulted from immigration of beetles from an
uncontrolled epidemic, beetle-proofed stands were heavily impacted. Effect
MPB
of treatment on ability to resist attack was not as important as the reduction
in frequency of attacks in beetle-proofed stands. Stands can be beetleproofed when attack is because of expansion of resident populations, but
does not protect against immigration from an epidemic.
WSB and
DFDM
BC
(Tweedsmuir LPP
PP)
Confirmed earlier studies indicating that Rx fires must be very hot to control
MPB. Differs from earlier studies that suggest that burned areas are highly
MPB
attractive to MPB. [Several sentences indicate that burned PP ARE highly
attractive to MPB]
Natural Resources
Canada Information
Report
Field based
research
LPP
E OR
Forest Science (P)
PP
Host
Field based
research
Location
MPB in LP stands: some of the oldest trees in thinned plots seemed to be
resistent to MPB attack, unrelated to vigor, size, or position relative to other
attacked trees. In general, beetles showed preference for larger trees.
MPB
Smaller trees rarely attacked unless in proximity to larger ones. Thinned
plots were initially unattractive to beetles but when attacks did occur,
colonization was not different from unthinned plots.
Organism
Black Hills
SD
Forest Science (P)
Field based
research
Notes
Attacks of MPB in PP stands tended to occur in clusters. TPA was the most
significant parameter and BA modified the behavior of TPA in the model.
Trees infected by Armillaria were very likely to be attacked, regardless of
MPB
size. Mean stand densities are not very useful when stands are
heterogeneous w/ respect to tree density and size. Within a stand, dense
portions are at greater risk to MPB.
Outlet (P = peerreviewed)
Research Type
Insects and their Management Papers
Other
121
2000
1998
1999
2004
2004
2000
McMillan and Allen
Negron
Powers et al.
Daterman et al.
Dwyer et al.
Greear
Mason and
Wickman
1991
2001
Date
Leslie and Bradley
Authors
Modeling /
theoretical
Project
Linked field and
landscape level
studies
Field based
research
Field based
research
Literature Review
Research Type
Concludes that frequency and severity of epidemics of DFB increase
because of industrial timber management practices. Salvage and trapping
are considered stop gap measures that may be necessary while forests are
DFB
undergoing restoration toward historical composition, structure, and
functioning. Improving stand vigor is important. Reducing stocking and/or reintroducing fire are needed.
Silva Ecosystem
Consultants
Organism
Notes
Outlet (P = peerreviewed)
USFS Project Report
Forest Ecol. And Mgmt.
Favor seral non-host species on high risk sites
(P)
Nature (P)
DFTM
DFTM
defoliators
Prior to attack, stands had high densities, large percentage of DF, and poor
Forest Ecol. And Mgmt.
growth for previous 5 years. Initial amount of DF BA predicts loss of DF BA DFB
(P)
during attack.
Over long timeframes and at the regional scale, DFB outbreaks associated
with windstorms and drought. At the landscape scale, outbreaks associated
with drier sites - south facing slopes, lower elevations and areas with more
Landscape Ecology (P)
DFB
mature and old growth conifer forest. Clustering of mortality occurred at 3
levels: clusters of 2-50+ individual trees; these were clustered at scales of 1
and 4 km.
Western J. Applied For.
DFTM
(P)
Three-fold increase in understory forbs, shrubs, and grasses with DFB
outbreak. Also conifer regeneration - nearly all DF. Reduced DF basal area
and average stand DBH. Higher mortality in stands with initially high DF BA.
USFS Technical Report Where tree mortality is heavy, reductions in BA are 40-70%. Salvage
DFB
harvesting can capture some economic value but does not reduce beetle
populations. DFB attacks are most successful in unmanaged, overstocked
stands with high percentage of large diameter DF.
Insects and their Management Papers
over range
E OR
none
over range
OR
CO
WY
over range
Location
DF / true fir
DF / GF
various
DF / true fir
DF
DF
DF
DF
Host
Other
122
Yale University
Global Institute of Sustainable Forestry
Chadwick Oliver
Faculty Director
Mary Tyrrell
Executive Director
Barbara Ruth
Program Coordinator
Since it's founding in 1901, the Yale School of Forestry & Environmental Studies has been in the forefront of developing
a science-based approach to forest management, and in training leaders to face their generation's challenges to
sustaining forests. The School's Global Institute of Sustainable Forestry continues this tradition, in its mission to integrate,
strengthen, and redirect the School's forestry research, education, and outreach to address the needs of the 21st
century and a globalized environment. The Global Institute fosters leadership through innovative programs, activities,
and research to support sustainable forest management worldwide.
The Global Institute has become the center for forestry at the School, coalescing and coordinating activities through
programs focused on specific areas of research, including Forest Health, Forest Physiology and Biotechnology, Forest
Policy and Governance, Landscape Management, Private Forests, and Tropical Forestry. The Institute is home to the Yale
School Forests, 10,880 acres of managed forests in New England used for education and research; and is host to The
Forests Dialogue, an international group committed to the conservation and sustainable use of forests. The Yale Forest
Forum (YFF) is the convening body of the Global Institute of Sustainable Forestry. Through YFF, the Institute holds
events at the Yale School of Forestry & Environmental Studies involving stakeholders from diverse sectors.
For more information or additional copies of our publications, please contact us at:
Yale Forest Forum
360 Prospect Street
New Haven, CT 06511
Phone: (203) 432.5117 Fax (203) 432.3809
Email: [email protected]
Web: yale.edu/gisf