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United States Department of Agriculture

Agricultural Research Service


Location: Range Sheep Production Efficiency Research

2008 Annual Report

1a. Objectives (from AD-416)
The overall objectives are to develop accurate and efficient monitoring methods, management guidelines, and decision support tools for use on rangelands. These methods, guidelines, and tools will help rangeland managers maintain or improve the health of the nation’s rangelands. The following are our specific objectives. Objective 1: Evaluate newly developed monitoring technologies for landscape-scale assessment of the effects of rangeland management activities, including grazing and fire, on vegetation, ground cover, and herbivore selectivity. Subobjective 1.A: Quantify the accuracy, precision, and efficiency of very-large-scale-aerial (VLSA) and close-to-earth (CTE) imagery for measuring rangeland vegetation. Objective 2: Develop science-based grazing management strategies and decision support systems that can be used to guide managers to maintain or improve the ecological function of western rangelands. Subobjective 2.A: Assess the effect of shifts in plant species composition due to grazing and fire disturbance on ecological functions such as productivity, nutrient cycling, and hydrological function. Subobjective 2.B. Develop parameterization algorithms for the Rangeland Hydrology and Erosion Model (RHEM) from existing and newly collected rangeland hydrology data sets. Subobjective 2.C: Assess the indirect effects of sheep grazing activity, such as bedding and stream crossing, on infiltration, soil erosion, and water quality.

1b. Approach (from AD-416)
Subobjective 1.A. CTE imagery will be collected in 2 yr before and after grazing to determine whether this imagery can be used to accurately assess changes in vegetation due to grazing. The CTE method will be compared with more conventional methods. VLSA imagery will be collected at several scales from pastures that differ with respect to burning and postfire grazing rest to determine the efficiency and degree of specificity that vegetation classification can be accurately made with this methodology. Likewise the VLSA method will be compared with conventional methods. Subobjective 2.A. Prescribed fire in the spring, fall, or an unburned control will be the main plot treatments, and the burns will cause a shift in vegetation composition for the mountain big sagebrush community at the research location. Following the fire disturbances, different periods of postfire grazing rest will be imposed on subplots which may alter the rate of succession toward the preburned state for the burned main plots. Measurements of soil erosion due to wind and simulated rainfall, soil nutrient dynamics, and plant productivity, and animal productivity and behavior will be measured in each burn/postfire grazing rest treatment combination to determine what effect the resulting shifts in vegetation composition have on ecological function of this plant community. Subobjective 2.B. Data from Subobjective 2.A and other collaborators' data will be used to develop parameterization algorithms for RHEM. Multiple regression techniques will be used to develop algorithms that utilize plant and soil characteristics to estimate soil erodibility and hydraulic roughness. Subobjective 2.C. Sheep will be bedded on bedgrounds at our summer range. Measurements of infiltration, erosion, and runoff water quality will be measured from three treatments. The three treatments will be within the bedground and bedded in the measurement year, within the bedground but not bedded in the measurement year, outside the bedground in a similar site but only grazed in the measurement year.

3. Progress Report
Rangeland disturbances, such as herbivory and fire, influence plant communities and ultimately the performance of ecological processes. U.S. Sheep Experiment Station (USSES) research focuses on determining whether new technologies, such as digital imagery, can better enable rangeland managers to make reliable assessments, characterizing how well ecological functions are performed over a range of plant community phases, and developing grazing and fire management strategies that shift plant communities to target states and phases in a mountain big sagebrush site. USSES scientists and collaborators used Systeme Pour l’Observation de la Terre-5 (SPOT-5) imagery to develop a spectral mixing model to classify shrub cover in mountain big sagebrush communities. One model was based on postfire (SPOT-5) imagery only, and the other model was based on prefire and postfire SPOT-5 imagery. The models were evaluated and compared using a burned area at the USSES. The results of the research indicate that satellite imagery can be used successfully to estimate shrub cover in mountain big sagebrush communities, and shrub cover in mountain big sagebrush is fully recovered within 27 years after fire. The research addresses NP 215 Pasture, Forage, Turf and Rangeland Systems Action Plan for 2007 through 2012. Component 1: Rangeland Management Systems to Enhance the Environment and Economic Viability; Problem Statement A: Need for economically viable rangeland management practices, germplasm, technologies and strategies to conserve and enhance rangelands ecosystems.

4. Accomplishments
1. Monitoring invasive weeds: Spotted knapweed rapidly invades and destroys native rangelands. Cost-effective, landscape-scale monitoring tools are needed to accurately and rapidly identify spotted knapweed plants in sagebrush ecosystems. In cooperation with scientists at the ARS, Rangeland Resources Research Unit, Cheyenne, Wyoming, scientists at the U.S. Sheep Experiment Station, Dubois, Idaho, have established that very-large-scale-aerial imagery is an effective tool for monitoring spotted knapweed occurrence and frequency in various sagebrush steppe terrains. Successful publication of these data will result in monitoring tools that are more suited for landscape scale monitoring of extensive rangelands. This research contributes to NP 205, Rangeland, Pasture, and Forages: Component I, Ecosystems and Their Sustainable Management, Problem Statement B, Monitoring and Assessment Technologies and Problem Statement E, Managing Degraded Systems; Component IV, Grazing Management: Livestock Production and the Environment, Problem Statement B, Grazing Impacts on Ecosystems; and Component V, Integrated Management of Weeds and Other Pests, Problem Statement A, Invasive and Noxious Weeds.

5. Significant Activities that Support Special Target Populations

Review Publications
Mitchell, R., Moffet, C.A., Sosebee, R. 2007. A physiological basis for controlling leafy spurge on nebraska rangeland. Rangelands 29(6): 12-14.

Pierson, F.B., Robichaud, P.R., Moffet, C.A., Spaeth, K.E., Hardegree, S.P., Clark, P.E., and Williams, C.J. 2008. Fire Effects on Rangeland Hydrology and Erosion in a Steep Sagebrush-Dominated Landscape. Hydrological Processes: 22, 2916-2929.

Pierson, F.B., Robichaud, P.R., Moffet, C.A., Spaeth, K.E., Williams, C.J., Hardegree, S.P., and Clark, P.E. 2008. Soil water repellency and infiltration in coarse-textured soils of burned and unburned sagebrush ecosystems. Catena 74:98-108.

Last Modified: 10/19/2017
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