Structure dependence of plant communities phytomass of Tuva highlands on slope exposure

The study is devoted to revealing of structure dependence of plant communities phytomass in the highlands of Tuva on the slope exposure. As a re-sult of analysis the author first points out that the total reserves of phytomass gradually increases from the tops of the mountains and from the west-ern slopes (3000 g/m2) to the north (5500 g/m2). The largest reserves of shrubs, sedges and mortmass are formed just on the eastern slopes, which is apparently due to more favorable hydro-thermal conditions. Shrub fraction participation is significant in dry, willow and crowberry tundras, confined to the limited tops of mountains and the north slope exposure (110-120 g/m2) and the west slope exposure (100 g/m2). It is interesting to note that in the spore-bearing plants the greatest re-serves of subterraneus biomass of lichen fractions formed on the southern slopes and on mountain tops (250-310 g/m2), the lowest are on the eastern, northern and eastern slopes of the mountains (140-160 g/m2). According to the reserves distribu-tion of subterraneus phytomass of plant communi-ties it is apparent that a significant amount of subterraneus plant organs is characteristic of the northern slopes (from 3800 to 4500 g/m2), on the other hand, the smallest were on western slopes and tops of the mountains (up to 2400 g/m2). Spe- cial attention is paid to the ratio of subterraneus and terraneous phytomass of which is on the northern slopes and the tops of the mountains ranges from 4.5 to 5.2, on the eastern, southern and western slopes are from 6 to 6.5, indicating a shift in the subterraneus phytomass environment in general.