放牧对青海湖北岸高寒草原植物群落特征的影响

Effects of grazing on community characteristics of alpine meadow on the northern shore of Qinghai Lake,China

基于青海湖北岸高寒草原连续3年放牧控制试验,研究了暖季和冷季放牧草地植物群落特征的变化。结果表明,暖季和冷季放牧草地群落地上生物量均随放牧强度的增加呈现下降趋势,禾本科地上生物量的变化趋势基本与群落地上生物量的一致;中度放牧对暖季放牧草地植被的影响程度高于冷季放牧草地;围栏封育区和冷季重度放牧草地的优势种均为紫花针茅(Stipapurpurea)和矮嵩草(Kobresia humilis),暖季放牧各放牧小区和冷季放牧草地轻度和中度放牧处理优势种均为紫花针茅和披针叶黄华(Thermopsis lanceolata);随放牧强度的增加,暖季放牧草地群落物种多样性指数和均匀度指数表现出先降低后增加的趋势,冷季放牧草地群落物种多样性指数和均匀度指数表现出增加的趋势,但是多样性指数在暖、冷季放牧草地均以重度放牧区最高。

A three year grazing trial was conducted in a two seasonal grazing （warm-season and cold-season） pasture in alpine meadow to study the variations of the plant community characteristics in the warm-season pas- ture and winter pasture. In the two seasonal grazing pasture, the aboveground biomass of plant communities decreased with grazing intensity increasing, and the aboveground biomass of graminoid had similar performance with plant community. The influence of grazing treatments in warm-season pasture was higher than that in win- ter pasture. The dominant plant species under no grazing, heavy grazing in cold-season pasture were Stipa purpurea and Kobresia hurnilis, whereas the dominant species under the other grazing treatments were S. purpurea and Therrnopsis lanceolata. The diversity index and evenness index of the plant community in warm-sea- son pasture firstly decreased and then increase with grazing intensity increasing, however, these two indices of the plant community in cold-season pasture increased with grazing intensity increasing. For warm-season pasture and cold-season pasture, the diversity index was the highest under heavy grazing intensity.