Quantifying the efficacy of management methods to control Bromus tectorum in the Centennial Valley of Southwest Montana
Bromus tectorum, more commonly known as cheatgrass, is the epitome of an aggressive invader. It has been widely documented to create monocultures in the Great Basin. However, there is a paucity of research on B. tectorum in the north-eastern sagebrush steppe ecosystem – such as southwest Montana. The environmental impacts of dense cheatgrass stands primarily result in the degradation of rangeland, including loss of native species, changes in disturbance regimes, nutrient cycling, and though less documented, shifts in belowground communities. The corresponding changes in ecosystem function associated with loss of biodiversity is often quantified in terms of financial detriment to ranchers, who lose valuable native communities that provide nutrient rich forage for livestock, and negative impacts to native fauna such as sage grouse and pronghorn antelope.
Managing B. tectorum has proved challenging and three main management approaches are prevalent: herbicide application and seeding, both of which are costly, and targeted grazing. My research explores the effect of herbicide and seeding. Focusing specifically on three objectives, to: 1) quantify the effect of herbicide (imazapic) on B. tectorum and native plant communities; 2) evaluate the benefits of seeding infested patches after herbicide application to help prioritize seeding efforts based on invaded patch size; and 3) investigate the success of different seeding strategies. My research will improve our understanding of methods to control B. tectorum in this region of the sagebrush steppe, and as a result glean valuable insight for ranchers and land managers, allowing them to prioritize resource allocation most effectively to reduce the negative impacts of cheatgrass, and restore native ecosystem function.