RMRS scientists have teamed up with managers and researchers at Bridger-Teton National Forest and Colorado State University to compare herbicide treatments to reduce cheatgrass seedlings, allowing restoration of native sagebrush grassland plant communities. An herbicide currently in use for cheatgrass control (imazapic) is being compared to indaziflam (not currently labeled for use on rangelands) for efficacy in selective reduction of invasive annual grass abundance over a three to five year period on shallow rocky south-facing slopes in the Wind River mountain range.
The Region 4 Science Partner Program has enabled RMRS scientists to join a team that has been conducting studies addressing the above-mentioned management needs. RMRS personnel have reviewed experimental design and protocol to ensure that the data collected can be used to address National Forest System (NFS) specific management challenges. They have visited the study site and participated in data collection efforts in order to understand the management history and current conditions of both the study site and the larger management areas potentially affected by the project outcome. RMRS personnel further assisted in a project presentation to Regional Leadership Team members responsible for approving proposed funding to complete the study.
Currently available herbicides and ground application methods for control of annual invasive grasses such as cheatgrass have come under scrutiny for non-target species impacts and logistic constraints. The available herbicide imazapic (Plateau®) has been found to cause damage to native perennials and requires frequent reapplication to maintain control of cheatgrass. There is a need to identify an effective long-term (>3 yrs) ground applied herbicide treatment to selectively reduce invasive annual grass abundance while minimizing harm to established native plants in sagebrush grasslands. There is a concurrent need to determine the effectiveness of aerial applications of indaziflam (Esplanade®) herbicide to selectively reduce invasive annual grass abundance while maintaining or increasing the abundance of established native plants in sagebrush grasslands.
The project is expected to identify effectiveness, relative impacts to non-target species, specific application rates, optimal treatment dates, re-treatment interval, and feasibility of aerial application for an herbicide with significant potential to bolster restoration efforts on annual invasive grass infestations NFS-wide. The approach involves management/research collaboration to solve problems, with multiple organizations contributing to the project.
The study will quantify relative impacts of the herbicides indaziflam and imazapic on non-target vegetation species, which will inform future cheatgrass treatment in western Wyoming. Collected data will be used to address NFS specific management issues, such as effects to sage grouse habitat, and an EIS for invasive species management (in progress) for the Bridger-Teton NF.