Rates of change in invasive annual grass cover to inform potential management opportunities across the sagebrush biome of the western United States

We used Rangeland Condition Monitoring Assessment and Projection (RCMAP) maps of annual herbaceous fractional components (mostly invasive annual grasses) to calculate mean rate of change in invasive annual grass cover over five-year time periods (ratesOfChange1987_2021.zip). We also created a map that identifies zones of the sagebrush biome that could be prioritized for different management goals (managementOpportunities.zip). The invasion of annual grasses has altered fire regimes and has contributed to the decline of sagebrush ecosystems. The vast expanse of annual grass invasions has required land managers to prioritize treatments in locations where they expect to be able to make a meaningful impact on invasion outcomes. Maps of invasive annual grass cover are useful in that they show the extent and severity of the invasion, but on their own, cover maps do not illustrate context such as how invasive cover is changing over time (i.e., increasing, stable, decreasing). The rate of change in invasive annual grass cover describes the trajectory of invasion. This information can be used by land managers to fine-tune priority locations and strategies for invasive species treatments in addition to other data sources (e.g., invasive annual grass cover maps).

本研究借助牧场状况监测评估与预测（Rangeland Condition Monitoring Assessment and Projection）生成的一年生草本组分占比分布图（以入侵性一年生草本为主要组分），计算了1987至2021年间五年时段内入侵性一年生草本覆盖度的平均变化速率（数据集文件：ratesOfChange1987_2021.zip）。同时，本研究还绘制了可针对不同管理目标划定优先处置区域的蒿灌丛生物群落分布图（数据集文件：managementOpportunities.zip）。一年生草本入侵已改变火灾发生格局，并加剧了蒿灌丛生态系统的衰退。大范围的一年生草本入侵事件迫使土地管理者优先在有望对入侵治理成效产生显著积极影响的区域开展处置工作。入侵性一年生草本覆盖度分布图虽能展示入侵的范围与严重程度，但仅靠此类覆盖度分布图无法体现诸如入侵覆盖度随时间的变化趋势（即增长、稳定或下降）这类背景信息。入侵性一年生草本覆盖度的变化速率可反映入侵的动态轨迹，土地管理者可结合该信息与其他数据源（如入侵性一年生草本覆盖度分布图），进一步优化入侵物种治理的优先区域与处置策略。