Community Rank Explanation
Conservation ranks are assigned to species and communities so that at-risk elements can be prioritized for conservation efforts. The international network of Natural Heritage Programs employs a standardized ranking system to denote global (G -- range-wide) and state status (S) (NatureServe 2003). Ranks range from 1 (critically imperiled) to 5 (demonstrably secure), reflecting the relative degree to which they are “at-risk”. Rank definitions are given below along with rank qualifiers. A number of factors are considered in assigning ranks -- the number, size and distribution of known occurrences, and the threat to their integrity or existence. For more information see NatureServe Explorer Conservation Status Ranks.
For example, Baltic rush (Juncus balticus) Herbaceous Vegetation is ranked G5 S5, common, abundant and not vulnerable throughout both its range in Montana and elsewhere. It occurs in every western state except Arizona.