Effects of Ventenata dubia removal on rangelands of northeast Wyoming

Abstract Ventenata [Ventenata dubia (Leers) Coss.] is one of several annual grass invaders of the western United States. Ventenata dubia is documented reducing the forage availability for livestock and wildlife as well as lowering biodiversity in the Great Basin. This species has recently spread to the Great Plains, where it could bring these impacts with it. We attempt to answer questions on whether or not conservation practices, in this case removal of V. dubia with herbicide, result in recovery of forage resources and biodiversity. We answer these questions by measuring biomass, cover, and nutrient content 1-yr posttreatment at 9 sites in Sheridan County, WY, conducted in two years. Perennial grasses have higher crude protein and total digestible nutrients than V. dubia, and removal of V. dubia resulted in a positive perennial grass response both years. Further, the differences in pattern of growth between perennial and annual species, with annual grasses quickly senescing early in the year, make perennial grasses a more dependable forage base with higher available nutrients. Interestingly, total biomass and nutrient mass did not change after V. dubia removal due to equal replacement with perennial grasses. Species richness and diversity were unaffected by removal of V. dubia. Our results suggest that managing invasive annual grasses, particularly V. dubia, in the Northern Great Plains can improve forage resources for livestock and wildlife while maintaining species diversity. Therefore, proactive monitoring and management efforts to prevent spread should be prioritized in this region.