Great Basin Naturalist
Volume 49 | Number 1
Article 12
1-31-1989
Effect of timing of grazing on soil-surface
crytogamic communities in a Great Basin lowshrub desert: a preliminary report
James R. Marble
Brigham Young University
Kimball T. Harper
Brigham Young University
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Recommended Citation
Marble, James R. and Harper, Kimball T. (1989) "Effect of timing of grazing on soil-surface crytogamic communities in a Great Basin
low-shrub desert: a preliminary report," Great Basin Naturalist: Vol. 49: No. 1, Article 12.
Available at: http://scholarsarchive.byu.edu/gbn/vol49/iss1/12
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EFFECT OF TIMING OF GRAZING ON SOIL-SURFACE
CRYPTOGAMIC COMMUNITIES IN A GREAT BASIN LOW-SHRUB
DESERT: A PRELIMINARY REPORT
James
R.
1
Marble and Kimball
T.
Harper
—Cover and species
richness of vascular and cryptogamic components of the plant community were
experimental grazing paddocks at the USDA/FS Desert Range Experimental Station, Millard County,
Utah. The grazing treatments considered have been applied continuously for over 50 years. The effects of heavy (ca 17
sheep days/acre) grazing treatment applied in two different seasons (early winter versus a split between early and late
winter) differed significantly between seasons. Cryptogamic cover and cryptogamic species richness both showed
larger decreases under early-late as opposed to early winter only grazing. Vascular plant cover (relative to controls) was
also reduced by early-late winter grazing, but not to a significant degree. Late season grazing, likewise, had no
significant effect on number of vascular species per transect.
Abstract.
inventoried
in
The importance
biological crusts are important in the soil sta-
of cryptogamic plants
mosses, and lichens) as soil stabilizers
on Great Basin rangelands has only recently
been appreciated by range managers. Management strategies that retain the positive effects of these nonseed plants, without eliminating grazing animals from the land, have not
yet been established. It is our purpose here to
report the effects of different seasons of sheep
grazing on cryptogamic plant covers at the
Desert Range Experimental Station in west
bilization process at that site.
(algae,
Communities of nonvascular cryptogamic
grow on or just below the soil surface.
The organisms that coexist in such communiplants
include species of fungi, algae, lichens,
When well developed, the crusts
and mosses.
play an important role in
of the crust resulted in the loss of
derson et al., Factors, 1982). The effects of
cryptogamic crusts on infiltration and sedirelease
were studied by Loope and Gifrecent studies have demon-
More
strated the importance of cryptogamic crust in
reducing
soil
erosion and increasing water in-
Lusby
et
al.
(1963, 1971)
lost
92% more
from control plots and
soil loss.
of species composition of
cryptogamic covers has been facilitated by
the work of Anderson and Rushforth (1976).
They provided photos and/or line drawings
of the major algal, moss, and lichen components of cryptogamic crust communities in the
Intermountain West. The role of cryptogamic
analysis
crusts in nitrogen fixation has
and Lusby
(1979) studied the effect of grazing and sediment yield on western Colorado watersheds.
Although Lusby and collaborators did not
record cryptogamic cover directly, their results are congruent with the hypothesis that
filtration.
1,441% more
The
and Harper 1972, 1977, Loope and Gifford
1972, Anderson et al., Recovery, 1982, An-
ment
sediment release by 31%. Lusby et al. (1963,
1971) and Lusby (1979) could not demonstrate
a significant change in vascular plant cover
associated with the large changes in runoff and
sediment release. Harper and St. Clair (1985)
found that physical disruption of cryptogamic
crusts (as might be caused by trampling by
herds of hooved animals) increased the average loss of water as runoff by 51% and increased soil loss by 686%. Complete removal
water than was
soil stabilization in
deserts (Fletcher and Martin 1948, Kleiner
ford (1972).
that
from winter
long (15 Oct. -15 May) to early winter only
(15 Oct. -15 Feb.) without a change in grazing
intensity reduced water runoff by 23% and
central Utah.
ties
They found
altering the season of grazing
been studied by
Rychert and Skujins (1974). The impact of 40
years of uncontrolled grazing on a soil cryptogam community in Navajo National Monument, Arizona, was studied by Brotherson
et al. (1983). They found considerable damage
to the cryptogamic community and less stable
'Department of Botany and Range Science, Brigham Young University, Provo, Utah 84602.
104
Marble, Harper: Cryptogamic Communities
January 1989
soil
conditions where grazing had been per-
mitted.
They recommended
that future range
research should include analysis of factors that
favor persistence of cryptogamic crusts
and
the impact of established grazing systems on
105
The effect of each grazing treatment was
analyzed in terms of cover and species richness (species per transect) for the following cover parameters: absolute cryptogamic,
absolute vascular, and percent of total contributed by cryptogams (cryptogamic/total).
those microplant assemblages.
The mean value
for
each
class along
each
transect was used as a single
datum to avoid
pseudoreplication. Data were compared us-
Site Description
The study area
is located at the Desert
Experimental Station in Millard
County, southwestern Utah. Since the Forest
ing the paired t-test (Zar 1974).
Range
Results
Department of Agriculture,
established the Desert Experimental Range
(DER) in 1934, the vegetational conse-
The early-late winter grazing treatment
showed significant differences between con-
quences of three intensities of grazing (light,
moderate, and heavy) have been tested in all
possible combinations with three different
grazing seasons (early, mid-, and late winter).
Each combination of intensity and time was
replicated twice. Each treatment was applied
trol and treatment plots in respect to both
cryptogamic cover and number of cryptogamic species as a percentage of total species (Tables 1, 2). The average number of
cryptogamic species per transect and the
average percent of total species contributed
by cryptogamic species were significantly re-
Service,
U.S.
to a separate 240-acre pasture.
Each pasture
contains two exclosures that initially had plant
cover comparable to that on the remainder of
the pasture.
The
1-acre (0.40-ha) exclosures
have been ungrazed throughout the period of
study.
duced
relative to controls
under
early-late
winter grazing (Table 2). Neither vascular
plant cover nor the number of vascular species
differed
significantly
treatment
plots.
between control and
Early winter grazing treat-
ment showed no significant differences for any
variable.
Methods
Within each of two grazed pastures (one
heavily grazed in early winter and the other
grazed at the same intensity but with half of
the use applied in early winter and the remainder in late winter), four sets of paired
transects were read. The heavy grazing treatment consisted of 17 sheep days of use per
acre. Each grazed transect was paired with a
transect approximately 16 m away and within
a control exclosure.
Each
transect consisted of
cover estimates at 10 subsample points. Cover
readings were made using a nested frequency
quadrat with eight points per subsample. The
0.25-m frequency quadrat was subdivided
into three smaller quadrats nested within; the
sizes of the four nested quadrats were 0.25,
2
Cover percent0. 125, 0.0625, and 0.0025
Discussion and Conclusions
A
cover
significant
is
reduction
in
cryptogamic
associated with late winter grazing as
indicated by readings of absolute cryptogamic
cover and cryptogamic cover as a percent of
total living cover. Late winter grazing, however, did not significantly reduce vascular
cover. The early winter grazing treatment, in
showed no significant difference in
any cover type between treatment and control
contrast,
plots.
Species
richness
comparisons show the
same pattern of response
number of points intercepting that type by all
points read along the transect (always 80) and
to grazing season as
cover comparisons. Early-late winter grazing
significantly reduced both absolute cryptogamic species richness and cryptogamic
species as a percentage of total species. Early
winter grazing, on the other hand, did not
significantly reduce either absolute number of
cryptogamic species or cryptogamic species as
a percentage of all species. The number of
vascular species was not significantly reduced
multiplying by 100.
under either grazing treatment.
m
.
ages were based on the number of points intercepting each cover type. Percent cover for
any cover type was computed by dividing the
Great Basin Naturalist
106
Table
1.
Cover values
for
cryptogamic and vascular
Table
2.
Vol. 49, No. 1
Species richness values for cryptogamic and
Grazed
vascular plant species on grazed and ungrazed transects.
intensity (heavy) but in
note significant differences between treatments and con-
Grazed transects are used at the same intensity (heavy)
but in different combinations of seasons. Asterisked t-values denote significant differences between treatments
trols.
and controls.
plant species on grazed and ungrazed transects.
transects are used at the
same
different combinations of seasons. Asterisked t-values de-
Marble, Harper.: Cryptogamic Communities
January 1989
erosion than winter-long (to 15 May) grazing
at
the
same
intensity of use. Thus, avoidance
of late winter use of desert ranges on the
Colorado Plateau and in the Great Basin may
reduce runoff and sedimentation downstream
and prolong the useful
life
of large reservoirs,
and other associated values. Cryptogamic crusts have the potential of slowing soil erosion by both wind
and water, enhancing infiltration of precipitation, and stimulating vascular plant growth
through improved soil water and available
their hydroelectric plants,
Fletcher,
soil
,
zona. Journal of Range
Monument, AriManagement 36: 579-581.
in
southeastern Utah. Journal of
27: 164-167.
C
1979. Effects of grazing on runoff and sedi-
Badger Wash
western Colorado, 1953-73. Geological Survey
Water-Supplv Paper 1532-1.
Lusby,
yield from desert rangeland at
G C V H
..
Reid.
andO D
Knipe. 1971. Effects of
grazing on the hydrology and biology of the Badger Wash Basin in western Colorado, 1953-66.
Geological Survey Water-Supply Paper 1532-D.
G C G T Turner, J R Thompson, and V. H.
Reid 1963. Hydrologic and biotic characteristics
of grazed and ungrazed watersheds of the Badger
Wash Basin in western Colorado, 1953-58. Geological Survey Water-Supply Paper 1532-B. 73 pp.
Rychert, R C and J Skujins 1974. Nitrogen fixation by
Lusby.
,
,
blue-green algae-lichen crusts in the Great Basin
Desert. Soil Science Society of America Proceedings 38: 768-771.
,
crust cover in Navajo National
soils.
in
1982. Factors influencing
Range Management 35: 18-185.
Anderson, D C K. T. Harper, and S R. Rushforth
1982. Recovery of cryptogamic crust from grazing
on Utah winter ranges. Journal of Range Management 35: 355-359.
Anderson, D. C, and S R Rushforth 1976. The cryptogamic flora of desert soil crusts in Utah deserts.
Nova Hedwigia 28: 691-729.
Brotherson. J D S. R. Rushforth, and J R Johansen
1983. Effects of long-term grazing on cryptogam
effects of
and Water Conservation
ment
Literature Cited
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Some
,
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development of crypcrusts in Utah deserts. Journal of
Martin. 1948.
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T.
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1977. Soil properties in relation to cryptogamic
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Loope, W. L. and G. F. Gifford. 1972. Influence of a soil
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