[Relation of the snow cover to the structure of vegatation in the alpine communities of the eastern Tsinghai-Tibet Plateau].

The type of snow cover considerably influences the sctructure of vegetation and production-related processes in alpine communities of diverse regions. The relation of snow cover thickness to the structure of apline plant communities in the eastern Tsinghai-Tibet Plateau (Sichuan, People's Republic of China) was studied by analyzing the vegetation in 251 sample areas grouped in five transects along the gradient of mesotopographic conditions and wintertime snow cover thickness. Considerable differentiation of plant communities related to snow cover thickness in revealed along the line from the northern to the southern slope. It is shown that the influence of snow cover on the distribution of particular plant species is significantly greater than the influence of soil properties (pH, content of humus, total phosphorus, potassium, and ammonia nitrogen in the upper strata of soil). Among the 56 herbaceous plant species and 7 shrub species studied, 52 herbaceous and all the 7 shrub species showed significant (P < 0.05) correlation (positive or negative) to snow cover thickness. Snow cover thickness appeared also significantly correlated to a number of soil properties: soil thickness, content of water, total phosphorus, and humus. But, in contrast to the alpine communities of the Caucasus and the Alps, no considerable acidification of the soil under snowflakes, due to perpetual removal of cations by melt water, was observed.