This indicator measures the numbers and geographic ranges of rare or “at-risk” species that occupy rangeland habitats for a significant portion of their life cycle, as well as the presence and extent of rangeland plant communities of concern. Trends in the number of at-risk species and communities help identify potential loss of historical and natural rangeland ecological functioning, as well as the loss of associated values and benefits. There are several metrics that could be used to describe the indicator. For species, metrics include the number of species, the number of populations per species, the abundance (number of individuals) per population, and the geographic range. For communities, metrics include the presence and number of at-risk communities, the number of stands of each community, the size of the stands, and the geographic range of the community.