The Arctic Species Trend Index
ASTIThe Arctic Species Trend Index (ASTI) was developed to provide a pan-Arctic perspective on trends in Arctic vertebrates. Tracking this index will help reveal patterns in the response of Arctic wildlife to growing pressures and thereby facilitate the prediction of trends in Arctic ecosystems. A total of 965 populations of 306 species were used to generate the ASTI. Overall, the average population of Arctic species rose by 16% between 1970 and 2004, although this trend is not consistent across biomes, regions, or groups of species. The terrestrial index shows an overall decline of 10%, largely a reflection of declines (-28%) in terrestrial high Arctic populations such are caribou, lemmings, and the high Arctic brent goose. Declines in terrestrial high Arctic populations may be partly due to the northward movement of southern species in combination with increasing severe weather events in the high Arctic and changing tundra vegetation. Although both freshwater and marine indices show increases, the data behind the freshwater index is currently too sparse in terms of species and populations, while the marine index is not spatially robust.