高山草甸群落生物量在融雪梯度上的变化

在青藏高原东部的一个高山雪床,沿融雪从早到晚的顺序设置3个融雪梯度部位,并对每个梯度部位的环境因子和该部位上的地上与地下生物量进行了测量和比较.3个梯度部位间的融雪时间、土壤含水量和温度日较差有显著不同,而土壤营养成分及pH无明显变化.从早融部位到晚融部位,地上生物量增加,地下生物量降低,地上与地下总生物量降低,地下生物量与地上生物量的比值增大.与晚融部位相比,早融部位的地上生物量主要集中于地上0～10 cm范围内,表明在早融部位植物地上部分有变矮的趋势;早融部位的地下生物量在土壤各深度分布相对较均一,而晚融部位地下牛物量则主要集中于地下0～10 cm范围内.雪场中各部位的土壤水分含量及地表温度差异对生物量的变化有较大的影响.图5表2参33

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

In an alpine snowfield 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 significantly different in the three sites, while no significant 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