PHYTOGEOGRAPHIC DIVERSITY OF THE PUTORANA FLORA (N SIBERIA)

567 vascular plants occurring in the Putorana Plateau (N Siberia) were subdivided into 7 main phytogeographic groups (chorotypes) through a numerical classification of their total distribution ranges. The distr ibution patterns of chorotypes are illustrated by chorograms, i.e. iso pleth maps obtained by programs of automatic mapping, showing the join t distribution of the species in the Northern Hemisphere, north of the Tropic of Cancer. The main chorotypes of the Putorana flora are: circ umboreal (28.2%), Amphi-Beringian (25.6%), central Siberian (13.1%), b oreal Eurasiatic (9.9%), E Siberian arctic (8.0%), NE Yakutian (7.8%) and circumarctic (7.4%). Some main distribution centers are evident fo r the plants of the Putorana flora; they are: a) central Siberia, part icularly the area around Lake Baikal (mainly species of boreal forest) , b) mountains of E Yakutia (mainly species occurring from the alpine to the forest belt), c) several narrow areas on the arctic coast of N Siberia (species of the alpine belt), d) the Amphi-Beringian region. T hese areas correspond to some main refugia for the boreal and arctic f lora during the Quaternary period. The results suggest that the Putora na Plateau can be considered as the westernmost extension of the Berin gian phytogeographic region in Eurasia.