Reference Concepts in Ecosystem
Restoration and Environmental Benefits
Analysis: Principles and Practices
Sarah J. Miller
Research Ecologist, Fluvial Geomorphologist
U.S. Army Engineer Research and
Development Center
Environmental Laboratory
Bruce A. Pruitt and Craig J. Fischenich, U.S.
Army Engineer Research and Development
Center Environmental Laboratory
Chuck H. Theiling, U.S. Army Corps of
Engineers, Rock Island District
Shawn B. Komlos, U.S. Army Corps of
Engineers, Institute for Water Resources
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July
2014
US
Army
Corps
of Engineers
Conference
on Ecological and
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Ecosystem Restoration
Environmental Benefits Analysis Program References
http://cw-environment.usace.army.mil/eba/index.cfm
Miller, S. J., B. A. Pruitt, C. H. Theiling, J. C. Fischenich, and S. B. Komlos. 2012.
Reference concepts in ecosystem restoration and environmental benefits analysis
(EBA): Principles and practices.” EMRRP Technical Notes Collection. ERDC TNEMRRP-EBA-12. Vicksburg, MS: U.S. Army Engineer Research and Development
Center. http://cw-environment.usace.army.mil/eba/,
http://el.erdc.usace.army.mil/elpubs/pdf/eba12.pdf
Pruitt, B. A., S. J. Miller, C. H. Theiling, and J. C. Fischenich. 2012. The use of
reference ecosystems as a basis for assessing restoration benefits. EMRRP
Technical Notes Collection. ERDC TN-EMRRP-EBA-11. Vicksburg, MS: U.S. Army
Engineer Research and Development Center.
http://cw-environment.usace.army.mil/eba/,
http://el.erdc.usace.army.mil/elpubs/pdf/eba11.pdf
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Ecological Reference Basic Definition
 a conceptual, spatial, or temporal comparison
 a target, benchmark, standard, model, or template
 from which or to which a site, state, process, or
range of ecosystem biological integrity, structure,
function, condition, or relative health are compared
 Institutionally “reference” has commonly come to
represent a high functioning condition or restoration
target, though the functional definition is broader
 First step in characterizing ecosystem reference
condition is classification, from which condition
indices have been developed for rapid asst.
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reference condition
 A reference condition is the set of attribute values or
quantifiable characteristics of the reference ecosystem.
 Physical, chemical, or biological parameters of
ecosystem structure or function can be represented by
a single value or a distribution.
Wetlands
River Basins
SAV
Sea Grass
Coastal
Stream Corridors
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Reference Condition Types Applicable to Aquatic Ecosystem Restoration
(modified from Stoddard et al. (2006)).
Table from S.J. Miller, B.A. Pruitt, C.H. Theiling, J.C. Fischenich, and S.B. Komlos. 2012. Reference Concepts in
Ecosystem Restoration and Environmental Benefits Analysis (EBA): Principles and Practices
Historical Condition
Pre-Agriculture
(HCPA)
Prior to intensive agricultural activity, meaning, "…very low pressure, without
the effects of major industrialization, urbanization and intensification of
agriculture, and with only very minor modification of physicochemistry,
hydromorphology and biology.” (Wallin et al. 2003)
Historical Condition
Pre-Industrial
(HCPI)
Prior to industrialization and urbanization in areas of influence to the
ecosystem (DuFour and Piegay 2009)
Historical Condition
Pre-Disturbance
(HCPD)
Prior to major impact or specific alteration or disturbance in an ecosystem
(DuFour and Piegay 2009)
Minimally Disturbed
Condition (MDC)
A condition representing the absence of local human disturbance, while
recognizing that minimal disturbance may be present due to human activities
affecting regional / global processes (e.g., climate change, deposition of
atmospheric contaminants below the threshold required to have measurable
impact on an ecosystem, etc.).
Least Disturbed
Condition (LDC)
A condition representing the least amount of human disturbance or alteration
in the current landscape context. In other words, “the best of what is left.”
Best Attainable
Condition (BAC)
The BAC represents a potential condition that could be achieved following the
implementation of all available BMPs at a site. The BAC reflects
a desired
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future condition given current constraints.
Future
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Figure from Bruce A. Pruitt, Sarah J. Miller,
Chuck H. Theiling, and J. Craig Fischenich.
2012. The Use of Reference Ecosystems as a
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Basis for Assessing Restoration Benefits ®
Part 2 – Reference Approaches
 A reference approach is a set of assumptions
and techniques for characterizing and
applying reference ecosystems and reference
conditions to practices associated with
ecosystem restoration.
 The reference approach establishes how and
which data are collected and analyzed to
represent selected reference conditions
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 Reference Approach: Historical Reference
 Description Use a selected historical reference condition
within project area (can be applied as off-site analogous
approach if conditions are met)
 Applicable Reference Condition HCPI or HCPA, HCPD if a
specific isolated event caused disturbance
 Requirements / Assumptions Requires the right data type /
resolution to set targets matched to objectives; if on-site, may
not require classification
 Benefits Opportunity to characterize adjustment of processes
to known stressors, if stressors not in flux or pre-disturbance
data are proximal, can represent target reference condition or
MDC
 Limitations Stressors may have changed, other parameters
may be changing, constraints may eliminate historical
reference from consideration as target reference condition
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Using Historical Reference Data to
Calibrate Habitat Models
 Case Study: Missouri River’s
Cottonwood Management Plan
(Omaha/Kansas City Districts)
►
Reference conditions for the model based
upon GLO-based vegetative data and GIS
representation of landuse conversions
over time
►
Data was normalized (scaled 0-1) and
used to calibrate the model
2
3
1.0
Suitability Index (SI)
0.8
1
0.6
0.4
0.2
Overall Study Area
0.0
0.0
0.5
1.0
1.5
2.0
2.5
Relative Complexity of Supporting (Non-Forested/Shrub) Habitats
(INTERSPERS)
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3.0
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 Reference Approach: On-site Analogous Reference
 Description Use present, on-the-ground conditions within
project footprint to determine reference
 Applicable Reference Condition LDC most likely
 Requirements / Assumptions Requires enough on-site
information to determine degree of function and degradation
and to set targets; may require consideration of broader
watershed conditions
 Benefits Low mobilization costs, parallel stressors, many
parameters equal (e.g., hydrology)
 Limitations May not represent target reference condition, may
not represent range of condition, may not represent ecological
trajectory
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 Reference Approach: Off-site Analogous Reference
 Description Use present, on-the-ground, ecologically
representative conditions outside project footprint to
determine reference
 Applicable Reference Condition LDC most likely, MDC possible
 Requirements / Assumptions Requires enough information at
a suitable off-site location to determine degradation and set
target, comparable class of system with parallel stressors,
measurable P/C/B parameters
 Benefits More likely to find reference that can help define
target reference condition with parallel stressors, parameters
 Limitations May not represent range of condition, may not
represent target reference condition, more cost to locate and
characterize another site, may not represent ecological
trajectory
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Project Site Before
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Project Site After
Reference Reach
Project Function
Reference Function
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 Reference Approach: Regional Index
 Description Use a range of existing reference sites to reflect a
continuum of conditions
 Applicable Reference Condition Any available
 Requirements / Assumptions Requires classification and
considerable data to characterize the range of the condition to
evaluate degradation and set targets
 Benefits Highly robust representative of full range of
conditions, puts projects into context, best characterization of
target reference condition, can speed overall assessment time
and reduce cost for subsequent projects once developed
 Limitations Requires sufficient data to develop index. This can
take time and might be too costly for a single project
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Minnesota River Basin Fish IBI
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 Reference Approach: Virtual (or constructed) Reference
 Description Use a combination of sources to represent target
reference condition for given physical setting, other constraints
 Applicable Reference Condition Any of HCPI, HCPA, HCPD,
MDC or LCD in combination with site or other data
 Requirements / Assumptions Typically requires data from
multiple sources, BPJ, and models
 Benefits Highly flexible if good information is available, high
resolution in defining target condition, best for use in settings
with many constraints, costs can be low if existing models, BPJ,
and collaborative processes are used
 Limitations Highly dependent on good information, good
interpretation/analysis of available information, can be quite
reliant on models, and subject to notable debate, costs can be
high if requiring new or extensive modeling
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Using Reference Data to Calibrate Habitat Models


Case Study: Middle Rio Grande Bosque
Ecosystem Restoration Feasibility Study
(Albuquerque District)
Reference conditions for the model
►
►
►
►
►


Quality of
The Fit
Must be politically palatable and reasonable
Must include a large number of sites from the
region
Must represent important aspects of pre-historical
conditions
May use minimal disturbance as the surrogate for
pre-historical conditions, given the difficulty of
establishing pre-historical conditions
Must be uniform across political boundaries and
bureaucracies (e.g., Federal, State, and local).
Reference
Datasets
Step 3:
Calibration
Model
Verification
30 sites were considered either reference
standard (optimal) or sub-optimal and were
chosen to represent the range of conditions
existing within the reference domain
Data was normalized (scaled 0-1) and used to
calibrate the model
Ecosystem
Response
Models
Fitted
Values
Average Native Sedge Canopy for
the Watershed + the Standard
Deviation for the Average Value
35% + 40% = 75%
SI = 1.0
Burks-Copes, K. A., and A. C. Webb. 2009. A Bosque Riparian
Community Index Model for the Middle Rio Grande, Albuquerque,
New Mexico. Model Documentation Draft Report. U.S. Army
Engineer Research and Development Center, Environmental
Laboratory, Vicksburg, MS.
Average Native Sedge Canopy for the
Watershed = 35%
SI = 0.75
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Critical Limitations How to Address Them
 Limitations of all the above reference approaches can be
addressed by
► continuing to compile organized regional reference
datasets
► using intentional documentation and adaptive management
► improving the quality of tools and techniques for defining robust
reference condition databases and models
 More refined characterization of range and quality of
reference condition through a regional approach will
enable better identification and description of functional
thresholds for ecosystem restoration targets
 Regional indices or reference indices that benefit multiple
projects / programs if data collection is implemented
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at the project scale
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Thank You!
Sarah J. Miller
Research Ecologist, Fluvial Geomorphologist
U.S. Army Engineer Research and Development
Center
Environmental Laboratory
[email protected]
601-64-5247
US Army Corps of Engineers
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