Changes in Community Biomass along Snow-melting Gradient in Alpine Meadow*

Abstract

In an alpine snowf ield on the eastern Qinghai-Tibetan Plateau,three sites were chosen along snow-melting gradient for this study,and the environmental factors and biomass of these sites were measured and compared. The result indicated that the snow melting time,soil water content and amplitude of diurnal temperature variance at soil surface were signif icantly different in the three sites,while no signif icant differences in soil nutrient contents (total N,total P,total K,soluble N,soluble P) and pH were found. From early-to late-melting sites,aboveground biomass,total biomass and ratio of below-to aboveground biomass increased,but underground biomass decreased. Comparison with late-melting site,the aboveground biomass in early-melting site largely distributed in a range of 0～10 cm above ground,indicating that plants in the early-melting site were shorter than those in the late-melting site. Unlike the aboveground biomass,the underground biomass in the early-melting site almost distributed evenly in soil at different depths. Underground biomass in the late-melting site mainly distributed in a layer of 0～10 cm below ground. All the results suggested that the changing trend of biomass was principally affected by soil water content and diurnal soil surface temperature variance in each site. Fig 5,Tab 2,Ref 33