Vad är rödlistan och hur bedöms växter och svampar?

In April 2015, the Swedish Species Information Centre launched the fourth Swedish Red List according to the criteria and categories of IUCN, covering plants, fungi, invertebrates and vertebrates. A total of 4 274 species are now nationally red listed. Here, the criteria and categories are presented, and also how the assessments are done. Emphasis is put on how to calculate more realistic population changes when data is in the form of occupied grid squares (e.g. 5 × 5 km) in repeated surveys. This includes 1) correction for errors caused by the grid resolution, where errors are most marked for abundant species and those with a clumped distribution, 2) correction for efforts between surveys, and 3) how to calculate the most realistic decline, within ten years or three generations, given a species' estimated generation time.