Regional invasive annual grass simulation models and invaded cover across the sagebrush biome (2022-2042)

This data release contains spatially explicit state-and-transition simulation model (STSM) packages, simulation results, and projected invaded cover layers of Invasive annual grasses (IAG). IAGs continue to spread within the sagebrush biome of the western United States, and managers need ways to scope IAG management strategy effectiveness for long-term strategic planning. We developed a simulation model and regional sampling framework that allows local-scale actions to be ‘scaled up’ to evaluate large-scale regional and biome-wide management strategy outcomes. We worked with natural resource managers and experts to co-develop a spatially explicit state-and-transition simulation model (STSM) of IAG dynamics in sagebrush landscapes to evaluate alternative management strategies.

The STSM represented the vegetation dynamics of IAGs in sagebrush ecosystems and included natural transitions (seed dispersal, cover establishment, and patch cover increase) and management transitions (inventory and treatment). STSMs were built as paired model extents (A/B) for five regions across the sagebrush biome that differed in underlying site conditions, susceptibility to invasion, and the amounts of IAG cover present (seedbank, less than 8% cover, 8-15% cover, 15-50% cover, greater than 50% cover, uninvaded), representing a range of simulated IAG outcomes across the biome. We ran two IAG management scenario simulations to establish a baseline for comparison with future analyses, one without management actions (No Management) and one where management was based on allocating treatments at a higher rate to areas with more invasive grass (Reactive Management). Management actions and treatment effort levels were based on historic treatment area polygon data for IAG management and represented treating approximately 1% of IAG infested areas of a landscape. Sagebrush Conservation Design (SCD; Doherty et al. 2022) classifications of the landscape were included in STSMs to track simulated outcomes relative to areas of importance and were also used for extrapolating results up to the sagebrush biome scale.

This data release is organized by landscape scales into two general datasets: the STSM libraries and projected invaded cover spatial layers. Invaded cover layers illustrate 5-year end-of-simulation average cover (2038-2042) for 10 model extents in 5 regions, and extrapolated invaded cover layers for the biome (2042) by management scenario. The structure of these data follow: A) RegionID_IAG.ssim – contains model libraries, input, and output files for the region, B) RegionID_InvadedCover – contains 5-year average invaded cover data for the region. Region 1 - contains datasets for model extents 1A (southwest Idaho) and 1B (southeast Oregon) in the Great Basin climate cluster (Intermountain West ecoregion), Region 2 – contains datasets for model extents 2A (northcentral Montana) and 2B (eastern Wyoming) in the Eastern Range climate cluster (Great Plains ecoregion). Region 3 – contains datasets for model extents 3A (northcentral Wyoming) and 3B (southwest Wyoming/northeast Utah) in the Wyoming climate cluster (Intermountain West ecoregion). Region 4 – contains datasets for model extents 4A (northeast Nevada) in the Great Basin climate cluster and 4B (central Utah) in the Eastern Range climate cluster (Southern Great Basin ecoregion). Region 5 – contains datasets for model extents 5A (Nevada/California) in the Bi-State climate cluster (Southern Great Basin ecoregion) and 5B (central Washington) in the Washington climate cluster (Intermountain West ecoregion).