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The Influence of Anchor-Chaining on
Watershed Health in a Juniper-Pinyon
Woodland in Central Utah
M. E. Farmer
K. T. Harper
J. N. Davis
Abstract-In 1990 the U.S. Forest Service anchor chained and
seeded 121 ha ofjuniper-pinyon woodland in Spanish Fork Canyon.
Twenty, 10 m 2 runoff-plots were established in 1991, to quantify
anchor chaining's effect on runoff and soil erosion. Plots were
paired, one in the chained area and one on comparable terrain and
soil type in the untreated juniper-pinyon woodland. Each enclosed
runoff-plot channels runoff water and suspended sediments into
collection containers. During five years of data collection, unchained plots produced 5.8 times more runoff and 9.2 times more
sediment than chained plots. Ground cover values for runoff plots
show that vegetation increased from 27.1 percent in 1991 to
41.3 percent in 1995 on chained plots, while litter increased from
22.6 percent to 51.5 percent during the same time period. Vegetation cover on untreated plots varied from 7.5 percent in 1991 to
3.4 percent in 1995. Litter cover averaged 18 percent. Results
indicate that anchor chaining significantly reduced runoff and soil
erosion by providing more protective ground cover.
Juniper-pinyon woodlands are an important rangeland
type in the western United States where it currently covers
about 24.3 million hectares. In Utah, Juniper-pinyon woodlands cover approximately 6 million hectares. These woodlands have greatly expanded their distribution in the past
150 years because of effective .fire control and heavy grazing
by domestic livestock (West 1984). Without competition
from a vigorous understory of grasses, forbs and shrubs and
occasional wild fires, pinyon-juniper woodlands have become more dense and claimed much of the available nutrient
and water resource previously used by a heavier cover of
understory plants (Doughty 1986). Areas dominated by
pinyon -j uni per prod uce little useable forage for wildlife or
domestic grazers, and the bare inters paces are prone to
erode during high intensity summer storms. Juniper and
pinyon trees can often survive for 600 to 1000 years. Without
some sort of mechanical removal, they may dominate a site
for years and put at risk soils that support the ecosystem
(West 1984).
In: Monsen, Stephen B.; Stevens, Richard, comps. 1999. Proceedings:
ecology and management of pinyon-juniper communities within the Interior
West; 1997 September 15-18; Provo, UT. Proc. RMRS-P-9. Ogden, UT: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research
Station.
M. E. Farmer is a Range Science Specialist, Utah Department of Agriculture, 735 N 500 E, Provo, UT 84606. K. T. Harper is a Professor in the
Departmen t of Botany and Range Science, Brigham Young University, Provo,
UT 84602. J. N. Davis is a Research Biologist, Utah Department of Wildlife
Resources, 735 N 500 E, Provo, UT 84606.
USDA Forest Service Proceedings RMRS-P-9. 1999
Anchor chaining is a tree removal technique that has
been used for the past 50 years. It is an economic method of
converting juniper-pinyon woodland to vegetation rich in
herbaceous perennial plants similar to that existing at the
time of settlement of the region by European peoples. Many
land managers have long assumed that reducing tree cover
and encouraging grass, forb and shrub cover had a positive
effect on infiltration, runoff and soil erosion on watersheds
heavily dominated by juniper and pinyon, but quantitative
data to support that assumption are uncommon. The purpose ofthis study is to quantitatively document the influence
of anchor chaining on watershed health in juniper-pinyon
woodland.
Methods
To determine the effects of chaining on runoff and soil
erosion, 10 paired, 10 m 2 runoff-plots were placed, one in the
chaining and one in a comparable unchained area. The
enclosed plots channel runoff water and suspended sediments down slope into a pipe connecting a series of covered
containers. A storage rain gauge was also placed near each
plot to estimate precipitation on the plot. Runoff water was
collected periodically and its volume recorded. Sediments
were collected, weighed, oven dried and re-weighed. Water
content in sediment samples was added to the runoff total.
Ground cover values were estimated using a modified
Daubenmire (1959) cover estimation procedure. Percent
cover of vascular plants, bare ground, rock, litter and cryptogamic plants was estimated annually at each runoff-plot.
Results --------------------------------------All runoff plots were placed during the summer of 1991.
Data were collected from August through October of that
year. During that period, untreated control plots produced
an average of nearly 6 times more runoff and 9 times more
sediment than chained plots. In 1992 data were recorded
from May through October. Control plots, during that six
month period, generated an average of 5 1/2 times more
runoff and over 6 times more sediment than the chained
plots (fig. 1 and 2). During the summer (May-October) of
1993, control plots produced 3 times more runoff and over
6 times more sediment.
In the first summer after chaining, chained plots averaged
27.1 percent vegetative cover, compared to 6.2 percent on
untreated plots (table 1). Protective ground cover consisting
of vegetation and litter, averaged 49.7 percent on chained
299
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Table 1-Relative percent ground cover of control and chained runoff plots.
Each year's total is an average of 10 measurements.
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1991
1992
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/
1995
1993
Figure 1-Average liters of summer runoff from
1991 to 1995. Each year's total is an average of 10
measurements.
plots and 20.9 percent on control plots. In 1992, vegetative
cover averaged 43.3 percent on chained plots and 7.3 on
control plots. Protective ground cover averaged 70.2 percent
on chained plots while control plots averaged 28.3 percent.
By 1995 vegetative cover on chained plots averaged 41.3
percent and protective cover (vegetation and litter) averaged
92.8 percent. Untreated control plots averaged only 3.4
percent vegetation cover and 18.2 percent protective cover.
Discussions __________
The primary forces which are related to water erosion are,
raindrop energy and surface runoff, which remove and
transport soil particles (Blackburn and others 1986). Vegetation is important in impeding overland flow and reducing
Unchained plots
1991
1992
1993
1994
1995
Average
Bare ground
Rock
Litter
Vegetation
46.6
31.1
14.7
7.5
31.6
40.1
21.0
7.3
39.3
33.5
19.6
7.6
50.6
25.1
19.4
4.8
43.8
33.5
14.8
3.4
42.4
32.7
17.9
6.1
Chained plots
Bare ground
Rock
Litter
Vegetation
43.1
7.2
22.6
27.1
25.1
4.7
26.9
43.3
19.5
6.9
37.9
35.6
27.1
3.8
38.1
31.0
15.4
13.7
51.5
41.3
26.0
7.3
35.4
35.7
raindrop energy. Blackburn and others (1986) state that
the amount of vegetative cover is the primary erosion controlling factor. Control areas on the Spanish Fork Site
during the study period, contained an average of6.1 percent
vegetation cover, 60 percent of which was tree canopy cover.
Simanton and others (1991) discovered that the significance of canopy cover was small compared to ground cover in
soil erosion prediction models. Khan and others (1988) found
that as canopy height increases the soil erosion rate also
increases. Ground cover of understory vegetation is most
effective at reducing soil erosion. Anchor chained sites in the
Spanish Fork study provided more uniform protective vegetation cover closer to the ground surface than untreated
juniper-pinyon sites.
Conclusions __________
Over the five year period of study, Anchor Chaining
allowed vegetative cover to increase 6 times on the average
plot and litter cover to increase an average of 2 times.
Runoff, on the chained plots, was reduced an average of
6 fold and erosion reduced an average of9 fold. Results show
that anchor chaining significantly reduced runoff and erosion by providing more protective ground cover.
////
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300
200
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1991
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1992
1993
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1994
Figure 2-Average grams of sediment yield from
10 plots during the summers of 1991-1995.
300
<fl. 15
,.---
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~
1995
/
Chained
Unchained
/
•
Grass
fZI
Forb
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Shrub
~
Tree
Figure 3-Average relative percent vegetation cover by
class of unchained and chained runoff plots from 1991-94.
USDA Forest Service Proceedings RMRS-P-9. 1999
Acknowledgments
This work was facilitated in active cooperation with the
Brigham Young University, Utah Division of Wildlife Resources, USDA Forest Service, Uinta National Forest, and the
Intermountain Research Station, Shrubland Biology and
Restoration Research Work Unit. Research was partially
funded by Pittman Robertson Agreements W-82-Rand W-135- R.
References ---------------------------------Blackburn, W. H., T. L. Thurow and C. A. Taylor, Jr. 1986. Soil
erosion on rangelands. In: Proceedings, Range Monitoring Symposium, Society of Range Manage. Denver, CO: 31-39.
USDA Forest Service Proceedings RMRS-P-9. 1999
Daubenmire, R. 1959. A canopy coverage method of vegetational
analysis. Northwest Sci. 33: 43-66.
Doughty, J. W. 1987. The problems with custodial management of
pinyon juniper woodlands. In: Proceedings, Pinyon-juniper
Conference, USFS Gen. Tech. Report INT-215: 29-33.
Khan, M. J., E. J. Monke, and G. R. Foster. 1988. Mulch cover
and canopy effect on soil loss. Trans. of the Amer. Soc. Agr.
Engr. 31: 706-711.
Simanton, J. R., M. A. Weltz, and H. D. Larsen. 1991. Rangeland
experiments to parameterize the water erosion prediction
project model: vegetation canopy cover effects. J. Range Manage. 44(3): 276-282.
West, N. E. 1984. Successional patterns and productivity potentials
ofpinyon-juniper ecosystems. In: Developing Strategies for Rangeland Management. Westview Press, Boulder: 1301-1332.
301