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United States Department of Agriculture

Agricultural Research Service

Research Project: NEW MONITORING TECHNOLOGIES FOR IMPROVING RANGELAND MANAGEMENT
2010 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
Spotted knapweed rapidly invades and destroys native rangelands. Scientists at the U.S. Sheep Experiment Station have established that aerial digital imagery is an effective tool for monitoring the frequency and density of spotted knapweed plants in various sagebrush steppe terrains. This research has resulted in monitoring tools that are better suited for landscape-scale monitoring of extensive rangelands. A manuscript describing this research was submitted to a peer-reviewed scientific journal.

Wildfires are part of rangeland ecosystems, and prescribed fires are part of programs to manage rangeland ecosystems, including shrub dynamics. Scientists at the U.S. Sheep Experiment Station and their collaborators used data from very-large-scale-aerial imagery to characterize the changes in horsebrush, bitterbrush, and sagebrush cover after wildfires and prescribed fires. A manuscript describing this research was submitted to a peer-reviewed scientific journal.

Wild and prescribed fires remove vegetation that could have been used for livestock grazing, but grazing too soon after a fire may compromise ecological processes. U.S. Sheep Experiment Station scientists conducted prescribed fires in the autumn of 2008 and spring of 2009 to initiate a long-term study of the effects of season of fire (i.e., autumn vs. spring) and postfire dormant-season grazing on plant community recovery rates and various ecological processes. Postfire data have been collected for rainfall simulations, soil nutrient dynamics, wind erosion, and very-large-scale-aerial-imagery validation experiments. Grazing treatments were imposed during the autumn of 2009 and will be imposed during the autumn of 2010 to determine sheep grazing behavior and performance and the effects of grazing on vegetation recovery.


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. Scientists at the U.S. Sheep Experiment Station have established that aerial digital imagery is an effective tool for monitoring the frequency and density of spotted knapweed plants in various sagebrush steppe terrains. This research has resulted in monitoring tools that are better suited for landscape-scale monitoring of extensive rangelands.

2. Shrub recovery after fire: Wildfires are part of rangeland ecosystems, and prescribed fires are part of programs to manage rangeland ecosystems, including shrub dynamics. Scientists at the U.S. Sheep Experiment Station and the ARS-Rangeland Resources Research Unit, Cheyenne, WY, used data from very-large-scale-aerial imagery to characterize the changes in horsebrush, bitterbrush, and sagebrush cover after fires. Shrub cover and composition changed for approximately 18 yr after the last fire. Horsebrush cover increased to approximately 3% over the first 9 yr and then decreased to approximately 0.2% over the next 9 yr, whereas bitterbrush and sagebrush cover increased for 6 and 18 yr, respectively, and then remained in a steady-state condition for the remainder of the 70-yr period studied. Steady-state cover for sagebrush, bitterbrush, horsebrush, and total shrub was 30, 3, 0.2, and 40%, respectively. This information will help land managers predict the optimal interval for prescribed burns and to plan landscape-scale prescribed fires to manage shrub cover.

3. Fire and ecological processes: Wild and prescribed files remove vegetation that could have been used for livestock grazing, but grazing too soon after a fire may compromise ecological processes. U.S. Sheep Experiment Station scientists conducted prescribed fires in the autumn of 2008 and spring of 2009 to initiate a long-term study of the effects of season of fire (i.e., autumn vs. spring) and postfire dormant-season grazing on plant community recovery rates and various ecological processes. Postfire data have been collected for rainfall simulations, soil nutrient dynamics, wind erosion, and very-large-scale-aerial-imagery validation experiments. Grazing treatments were imposed during the autumn of 2009 and 2010 to determine sheep grazing behavior and performance and the effects of grazing on vegetation recovery. The results of this research will enable land managers to better plan autumn and spring prescribed fires and improve land management after fires, including making a science-based decision about whether to permit moderate grazing within 1 yr after a prescribed fire.


Review Publications
Pierson Jr, F.B., Moffet, C.A., Williams, C.J., Hardegree, S.P., Clark, P. 2009. Prescribed-Fire Effects on Rill and Interrill Runoff and Erosion in a Mountainous Sagebrush Landscape. Earth Surface Processes and Landforms. 34:193-203.

Wei, H., Nearing, M.A., Stone, J.J., Guertin, D.P., Spaeth, K., Pierson Jr, F.B., Nichols, M.H., Moffet, C.A. 2009. A new Splash and Sheet Erosion Equation for Rangelands. Soil Science Society of America Journal. 73:1386-1392.

Last Modified: 10/21/2014
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