Moderate grazing during the off-season (fall-winter) reduces exotic annual grasses in sagebrush-bunchgrass steppe

Authors: Davies, Kirk; Boyd, Chad; Copeland, Stella; Bates, Jonathan - Jon

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: 3/28/2022
Citation: Davies, K.W., Boyd, C.S., Copeland, S.M., Bates, J.D. 2022. Moderate grazing during the off-season (fall-winter) reduces exotic annual grasses in sagebrush-bunchgrass steppe. Rangeland Ecology and Management. 82:51-57. https://doi.org/10.1016/j.rama.2022.02.003.
DOI: https://doi.org/10.1016/j.rama.2022.02.003

Interpretive Summary: Management is needed to reduce exotic annual grasses to prevent sagebrush-bunchgrass communities from transitioning to exotic annual grasslands. Some evidence suggests that grazing in the fall-winter may reduce exotic annual grasses, but has not been evaluated in sagebrush-bunchgrass communities. We investigated the effects of fall-winter grazing by cattle in sagebrush-bunchgrass communities. Fall-winter grazing reduced exotic annual grass cover and abundance and increased Sandberg bluegrass, a native perennial grass, abundance. Abundance of other vegetation was not influenced by fall-winter grazing. These results suggest that fall-winter grazing can be a valuable tool for reducing exotic annual grasses in sagebrush communities. This study is of interest to land managers, policy makers, and other scientists.

Technical Abstract: Exotic annual grass invasion and dominance of sagebrush-bunchgrass steppe is a concern because it decreases biodiversity and promotes frequent wildfires. Management is needed to reduce exotic annual grasses to prevent sagebrush-bunchgrass communities from transitioning to annual grasslands. Grazing during the off season (fall-winter) has shown promise at reducing exotic annual grasses, but it has not been evaluated in plant communities dominated by sagebrush and native bunchgrasses. We compared moderate grazing during the off season with not grazing in five Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & A. Young] S.L. Welsh)-bunchgrass communities in the northern Great Basin. Treatments were applied annually for 10 yr (2009-2010 through 2018-2019). Plant community characteristics were measured after treatments had been applied from 6 to 10 yr. Off-season grazing reduced exotic annual grass density and cover. After a decade, annual grass cover was twofold greater in ungrazed areas. Sandberg bluegrass (Poa secunda J. Presl) density increased with off-season grazing, but large bunchgrass density was similar between off-season grazed and ungrazed areas. Perennial and annual forb density and cover were similar between off-season grazed and ungrazed treatments. Biological soil crust cover was also similar between off-season grazed and ungrazed areas. The results of this study provide strong evidence that off-season grazing has application for managing exotic annual grasses in sagebrush-bunchgrass steppe. Considering the vast scope of the exotic annual grass problem, properly applied grazing may be the most cost-efficient tool to mediate the impacts of annual grass invasion.