Seed mix performance and cheatgrass suppression on arid rangelands.
The accidental and subsequent invasion of cheatgrass throughout millions of hectares of Intermountain West rangelands has truncated secondary succession by providing a fine-textured, early maturing fuel that has increased the chance, rate, spread, and season of wildfire. The restoration or rehabilitation of degraded rangelands throughout the Intermountain West is very challenging due to annual invasive species that exhibit high growth rates and seed production. The use of the pre-emergent herbicide, Imazapic, decreased cheatgrass densities >95% during the fallow year and before sowing seed the following fall during this study, which significantly reduced the cheatgrass competition for seedlings of seeded species. Seed mix performances were significantly higher in herbicide-treated plots than control plots for both sites for both years. Native, introduced, and native/introduced seed mixes were significantly more successful in the treated plots at the Bedell Flat site compared with the Antelope site for both years. Cheatgrass densities were significantly higher in the control plots at both sites for both years compared with herbicide/seed mix-treated plots. Success and failure of establishing perennial grasses in restoration or rehabilitation practices is highly dependent on proper seed and seed mix selections, seeding methodologies, and rates as well as favorable precipitation.