Virtual Posters

Extensive data on vascular plant species composition in 150 localities (“local floras”) in the Asian part of the Russian Arctic was obtained by the authors. Similar in size (100 km2) localities were studied very thoroughly, therefore species lists are highly comparable and any changes in diversity can be traced. They were chosen for biodiversity monitoring network. As the present scheme of floristic delimitation of the Arctic (Yurtsev, 1994) was produced (using extrapolation) earlier than the database had been created, our aim was to check if the local floras data support it. For this purpose we used both taxonomic and geographic characters of the floras. Existence of more or less sharp gradients in the presence and abundance of different longitudinal groups and fractions in local floras confirmed certain boundaries and revealed others, not reflected in the scheme (Figure). Among the latter the boundary separating Eastern Gydan from the rest of Yamal-Gydan subprovince and the border at the base of the Chukchi peninsula (marked by the distribution of 7 groups!) are the most important; the boundary along the Pyasina river which separates Western Taimyr and the border separating Beringian coast are of lower rank. Clusterisation on the base of similarity of geographical spectra proved the separation of 2 western subprovinces, rather high floristic unity of Taymyr’s subprovince, heterogeneity of Yamal-Gydan’s. In Chukotka’s province clustering showed: high similarity of floras of the Wrangel island and the coast of Continental Chukotka; essential difference between the coastal Beringian floras and ones from the inland of Chukchi peninsula, similarity of the latter with Southern Chukotka’s floras. These features were not reflected in the scheme. Study of local floras contributed in the investigating of the spatial differentiation of the plant cover and producing more accurate scheme of the floristic delimitation of the Russian Arctic.