Range size variation and diversity distribution in the vascular plant flora of the Eurasian Arctic

The distribution ranges of Eurasian arctic vascular plants are studied to identify and characterise significant range types and their distribution along longitudinal and latitudinal gradients, and to analyse the range size distribution of arctic plants. We also address the distribution of plant diversity in the Eurasian Arctic and possible environmental reasons for the patterns observed. Cluster and correlation analyses are conducted on a distribution database established for 1690 vascular plants observed in the Eurasian Arctic. The database records occurrences of the species separately for each of 184 partial areas encompassing almost the entire Holarctic. Highest species numbers of Eurasian arctic plants were observed outside the Arctic, namely in the high mountain ranges of Europe, Siberia and the Far East. Within the Eurasian Arctic, highest species numbers were observed in the European Arctic and Chukotka. The species of the entire Eurasian Arctic could be affiliated with 15 range types. These range types revealed that the Eurasian arctic flora has three major constituents: endemics and sub-endemics, species of three southern high mountain ranges, and widespread species. A principal ‘source of origin’ contributing to the diversity of the Eurasian arctic flora was not evident. Widespread species are more abundant in the western than in the eastern Eurasian arctic flora, where endemics and sub-endemics prevail. The current climate of the northern hemisphere, not only vegetation history, is identified as an important factor in shaping these patterns.