Floristic changes among vascular plants in the lower reaches of the Kolyma river on the latitudinal gradient.

摘要

Gradual changes of floristic complexes from the stripe of northern open forests to the subzone of the arctic tundras are followed along the unique for the Arctic compact (110 km) latitudinal profile in the Kolyma River lower reaches. The total floraof the region numbers 531 species and subspecies of the vascular plants, but only 111 species (20.9%) are present constantly in the mainland part of the profile and the form the "core" of the massive regional flora. The massive loss of the species is the main floristic change along the profile, whereas taxonomic and geographical diversities increase northwards. The most abrupt changes in the flora's composition take place on the border between typical and arctic tundra subzones. The changes are essentially weaker on the borders between southern and typical tundras and between tundra and taiga zones (at the tree line). The changes in the composition and structure of the local floras show that the main factor which determines the regional flora's changes along the latitudinal gradient is the temperature during the vegetation period.