Cheatgrass (Bromus tectorum) is an exotic annual grass that is increasingly degrading Southwestern forests and rangelands. It out-competes many native plants and as populations expand, continuous and highly flammable fine fuels develop that further threaten native ecosystems. Land managers are confronted with the challenge of maintaining ecosystem function and resiliency to cheatgrass invasion. In 1996 the Bridger-Knoll fire complex on the north Kaibab Plateau burned through critical mule deer (Odocoileus hemionus) native winter range and a majority of this area is now invaded by cheatgrass. We set up a field experiment to test the effectiveness of applications of Imazapic PLATEAU herbicide to control cheatgrass and seeding to restore native shrubs. The shrubs included Wyoming big sagebrush (Artemisia tridentata) and cliffrose (Purshia mexicana). We also set up experiments at the Rocky Mountain Research Station greenhouse to test the effects of PLATEAU on the seeded shrub species (also including saltbush (Atriplex canescens) because it was seeded on a larger scale) and cheatgrass at different growth stages.

Results/Conclusions Preliminary results from the greenhouse experiments suggest that PLATEAU is effective at killing cheatgrass (98% or greater mortality) regardless of growth stage, but may reduce native shrub germination by up to 90%. Established 4-month old native shrub seedlings are less sensitive to the herbicide. Post-treatment data from the field experiment will be collected in 2009, and will provide insights into the effectiveness of herbicide treatments and shrub seeding in restoring native plant communities. Given the vast acreages of cheatgrass infestations across the Intermountain west, studies quantifying the effectiveness and unintended consequences of potential control measures are critical for developing successful management to promote native plant sustainability.