USE OF GIS-APPROACH IN SEASONAL DYNAMICS OF ABOVEGROUND PHYTOMASS IN ARCTIC ECOSYSTEMS - FAD OR NECESSITY

Combinative method, describing the dynamics of above-ground living phy tomass of different ecosystems, was for the first time applied to the most representative region of world tundra biome (Taymyr peninsula, Ru ssia). The available field data, approximation models of phytomass sea sonal dynamics and the computation system with electronic map were use d. This allows to get correct seasonal spatial distribution of the mai n dynamic characteristics of tundra ecosystems. Its accuracy is up to 1 day over the territory in study (23.5 km(2); 73 degrees 15' N, 90 de grees 46' E). The new estimate of averaged seasonal aboveground phytom ass in Taymyr typical tundra is 3,7 tons per hectare of dry organic ma tter. The maximum seasonal increase of aboveground phytomass (1,2 tons . hectare(-1). year(-1)) estimated to be twice less than averaged Net Primary Production (2,4). Two basic patterns of phytomass seasonal dy namics in typical tundra were found. The grass-moss type (1) is charac terized with rapid growth, strongly marked maximum, and rapid decline at the end of the season. This type is mostly determined by changes in grass components of ecosystems. The lichen-shrub-moss type (2) has mo re gradual growth and decline, with poorly expressed maximum. This pat tern, in contrary, is mainly defined by changes in green parts of shru b components. The latter type occupies considerable part of territory (57,5%) and predominates in total phytomass (55%), but contributes les s to overall production (40% v. 60%). In typical tundra mosses are fou nd to be absolute predominants in overseasonal phytomass formation (71 ,7%). Besides, grasses participance in Production is proved to be the most important (52,9%). The absolute and relative abundance of grasses and grass-moss communities is the most important factor, determining overall phytomass dynamics and production in typical tundra.