Author
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Davies, Kirk |
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Svejcar, Anthony |
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Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/18/2008 Publication Date: 11/1/2008 Citation: Davies, K.W., Svejcar, A.J. 2008. Comparison of medusahead invaded and non-invaded wyoming big sagebrush steppe in southeastern oregon. Rangeland Ecol Manage 61:623-629 Interpretive Summary: Medusahead 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 non-invaded 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 non-invaded Wyoming big sagebrush steppe communities that had similar soils, topography, climate, and management. Non-invaded plant communities had greater cover, density, and biomass production of all native herbaceous functional groups compared to medusahead invaded communities. Sagebrush cover and density were greater in the non-invaded compared to the medusahead invaded communities. Species richness and diversity were greater in the non-invaded than invaded plant communities. 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. This information is useful to land and wildlife managers for determining the benefit of preventing and controlling medusahead invasions. This information is also useful to policy makers in determining the allocation of resources for and value of preventing and controlling medusahead. Technical 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 non-invaded 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 non-invaded Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh) steppe communities that had similar soils, topography, climate, and management. Non-invaded 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 non-invaded compared to invaded plant communities. Sagebrush cover and density were greater in the non-invaded compared to the medusahead invaded communities (P < 0.01). Biomass production of all native herbaceous functional groups were higher in non-invaded compared to invaded plant communities (P < 0.02). Perennial and annual forb biomass production was 1.9 and 45-fold more, respectively, in the non-invaded than invaded communities. Species richness and diversity were greater in the non-invaded 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. |
