Cheatgrass (Bromus tectorum) distribution in the intermountain Western United States and its relationship to fire frequency, seasonality, and ignitions

摘要: Cheatgrass (Bromus tectorum) is an invasive grass pervasive across the Intermountain Western US and linked to major increases in fire frequency. Despite widespread ecological impacts associated with cheatgrass, we lack a spatially extensive model of cheatgrass invasion West. Here, leverage satellite phenology predictors thousands field surveys abundance create regional models distribution percent cover. We compare presence probability, seasonality ignition source. Regional cover had low predictive power (34% variance explained), but based on threshold 15% differentiate high from overall accuracy 74%. achieves ≥ 15% over 210,000 km2 (31%) These lands were twice as likely burn those abundance, four times more multiple between 2000 2015. Fire probability increased rapidly at (1–5%) remained similar higher cover, suggesting that even small amounts ecosystem can increase risk. Abundant was also 10 days earlier interacted strongly anthropogenic ignitions. particularly human activity, awareness danger invaded areas could reduce This study suggests much abundant than previously documented greatly frequency,