Indaziflam for Cheatgrass (Bromus tectorum) control increased native species richness for up to 8 years in Colorado Front Range (United States) shrub‐steppe

Boulder County Open Space (BCPOS) manages properties in Colorado Front Range's shrub‐steppe with a high diversity of native species. BCPOS ecologists are concerned with the loss of habitat and diversity of native plant species and communities from Cheatgrass ( Bromus tectorum ), an invasive winter annual that seriously threatens biodiversity. Yearly evaluations were conducted for six to eight consecutive growing seasons after indaziflam herbicide application to assess long‐term effects of Cheatgrass and indaziflam on native species diversity at 12 locations in Boulder County, Colorado. A single application of indaziflam maintained 70–98% control of Cheatgrass up to eight summers after treatment. Species richness for forb, short‐lived, and total species groupings in treated plots increased over time, more than doubling compared to the non‐treated plot groupings. There were no significant treatment‐SAT effects in shrub or grass/sedge richness, although richness increased in treated plots over time. Indaziflam did not reduce desirable species richness, a concern for some land managers. The increase in desirable species in treated plots most likely resulted from an existing and resilient diverse native species seed bank. When restoring less degraded native plant communities, one indaziflam application was effective for long‐term Cheatgrass control, which likely increased resources available for the germination and establishment by the in situ native seed bank and existing plants. This case study demonstrates how controlling Cheatgrass increased native species richness on the Colorado Front Range shrub‐steppe. Indaziflam is an effective restoration tool that led to more diverse and resistant plant communities.