Conservation status assessments use a standardized method developed by NatureServe to determine the degree of rarity for plants, animals, and ecosystems. The NatureServe methodology ensures rank consistency and transparency between all rare species/ecosystems within Alaska and other U.S. states and Canadian Provinces. Alaska Center for Conservation Science is responsible for assigning a state conservation rank (S rank), while NatureServe assigns a global conservation rank (G rank). The conservation state ranks, symbolized by an S# or S#S#, represent the conservation status of the ranked species in Alaska. The number following the ‘S’ assigns the degree of rarity or imperilment.
A conservation status rank is calculated for a species based on its range extent, area of occupancy, number of occurrences, population sizes and trends, and threats to the species. Ecosystems are ranked based on similar criteria. Data supporting the ranks are gathered from field inventories, publications, reports, herbaria specimens, and the knowledge of species specialists, ecologists, and taxonomic experts. The data inform the criteria required by the NatureServe Rank Calculator to produce a preliminary rank. Based on expert review, that preliminary rank is either adjusted or accepted.