Bedreigde en kwetsbare vaatplanten in Nederland. Basisrapport met voorstel voor de Rode Lijst

In this publication five classes are treated: Lycopsida, Equisetopsida, Pteropsida, Pinopsida and Magnoliopsida. The present proposal replaces the “FLORON-Rode Lijst 1990” (Gorteria 16, 1990, 2-26). It meets the requirements of the IUCN criteria. Species are classified according to a combination of rareness and decrease into eight categories: ‘Not Evaluated’ (NB), ‘Data Deficient’ (OG), ‘Actually Not Threatened’ (TNB; IUCN: ‘Low Risk/Least Concern’), ‘Near Threatened’ (GE), ‘Vulnerable’ (KW), ‘Endangered’ (BE), ‘Critically Endangered’ (EB), and ‘Disappeared’ (VN; IUCN: ‘Regionally Exctinct’), the latter five forming together the Red List (RL2000). For this purpose 1490 species have been considered. The new List (Rode Lijst 2000) counts 499 species (38% of all relevant species): GE: 114 (23%), KW: 136 (27%), BE: 102 (20%), EB: 90 (19%), VN: 50 (10%). RL2000 is the result of treatments of the two national flora databases FLORIVON and FLORBASE, giving a picture of the decreasing and rare part of the Dutch flora between ca. 1935 and ca. 1999. The numbers of records presented are based on the 1x1 kilometer grid of the topographical map, which internationally is comparable with a singlepopulation size. RL2000 could largely be based on sound calculations. In comparison with the former List (RL90) 191 species changed in status: 74 are new, 117 species do not return on RL2000. After correction for differences in criteria, RL2000 is 10% longer than its predecessor. In a comment on RL2000 the species are treated according to habitat type. The most threatened habitat types are (number of species between brackets): all habitats on calcareous soil [arable fields (91%), wetlands (89%), grasslands (74%), forest edges (69%), woodlands (51%)], fen meadows (88%), heath land [wet (80%), dry (76%)], nutrient-poor waters (70%) and salt marshes (52%).