Comparison of Medusahead-Invaded and Noninvaded Wyoming Big Sagebrush Steppe in Southeastern Oregon |
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| Institution: | 1. Rangeland Scientist, United States Department of Agriculture–Agricultural Research Service at the Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, OR 97720, USA;2. Research Leader, United States Department of Agriculture–Agricultural Research Service at the Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, OR 97720, USA;1. Rangeland Scientists, US Department of Agriculture, Agricultural Research Service, Burns, OR 97720, USA;2. Associate Professor, Oregon State University, Department of Animal and Rangeland Sciences, Burns, OR 97720, USA;3. Southeast Oregon Project Manager, The Nature Conservancy, Burns, OR 97720, USA;4. Research Leader, US Department of Agriculture, Agricultural Research Service, Burns, OR 97720, USA.;1. Graduate Research Assistant, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA;2. Research Associate, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA;3. Professor and Extension Specialist, Bioagricultural Sciences and Pest Management Department, Colorado State University, Fort Collins, CO 80523, USA;1. Ecologist, US Department of Agriculture, Agricultural Research Service, Burns, OR 97720, USA;2. Rangeland Scientist, US Department of Agriculture, Agricultural Research Service, Burns, OR 97720, USA;4. Research Leader, US Department of Agriculture, Agricultural Research Service, Burns, OR 97720, USA;3. Restoration Ecologist, MPG Ranch, Missoula, MT 59870, USA.;1. Rangeland Scientists, USDA-ARS, Burns, OR 97720 USA; and;2. Research Associate, Oregon State University, Burns, OR 97720 USA;1. Research Ecologist, US Forest Service, Rocky Mountain Research Station, Reno, NV 89509, USA;2. Sagebrush Ecosystem Specialist, USDA Natural Resources Conservation Service, Redmond, OR 97756, USA;3. Research Ecologist, US Geological Survey, Forest & Rangeland Ecosystem Science Center, Corvallis, OR 97331, USA;5. Rangeland Ecologist, USDI Bureau of Land Management, Boise, ID 83709, USA;6. Presidential Management Fellow, US Forest Service, Rocky Mountain Regional Office, Golden, CO 80401, USA;1. Research Ecologist, US Department of Agriculture (USDA)−Agricultural Research Service (ARS) Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, OR 97720, USA;2. Rangeland Ecologist, US Department of Agriculture (USDA)−Agricultural Research Service (ARS) Eastern Oregon Agricultural Research Center, 67826-A Hwy 205, Burns, OR 97720, USA |
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| Abstract: | Medusahead (Taeniatherum caput-medusae L.] Nevski) is an exotic, annual grass invading sagebrush steppe rangelands in the western United States. Medusahead invasion has been demonstrated to reduce livestock forage, but otherwise information comparing vegetation characteristics of medusahead-invaded to noninvaded sagebrush steppe communities is limited. This lack of knowledge makes it difficult to determine the cost–benefit ratio of controlling and preventing medusahead invasion. To estimate the impact of medusahead invasion, vegetation characteristics were compared between invaded and noninvaded Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis Beetle & A. Young] S. L. Welsh) steppe communities that had similar soils, topography, climate, and management. Noninvaded plant communities had greater cover and density of all native herbaceous functional groups compared to medusahead-invaded communities (P < 0.01). Large perennial grass cover was 15-fold greater in the noninvaded compared to invaded plant communities. Sagebrush cover and density were greater in the noninvaded compared to the medusahead-invaded communities (P < 0.01). Biomass production of all native herbaceous functional groups was higher in noninvaded compared to invaded plant communities (P < 0.02). Perennial and annual forb biomass production was 1.9- and 45-fold more, respectively, in the noninvaded than invaded communities. Species richness and diversity were greater in the noninvaded than invaded plant communities (P < 0.01). The results of this study suggest that medusahead invasion substantially alters vegetation characteristics of sagebrush steppe plant communities, and thereby diminishes wildlife habitat, forage production, and ecosystem functions. Because of the broad negative influence of medusahead invasion, greater efforts should be directed at preventing its continued expansion. |
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