为了探索青藏高原湿润地区草地的演变规律和未来对气候变化的响应,以雅家埂高山带不同海拔草地为对象,研究了草地群落特征沿海拔梯度的变化,并分析了气候因子和土壤因子对群落特征的影响。结果表明:(1)沿海拔梯度草地群落特征具有明显分异,地上生物量随海拔升高呈现显著降低,而地下生物量和群落的根冠比呈现显著增加。群落多样性指数在较低海拔间呈现显著变化,而在较高海拔间变化不明显。总体而言,随海拔升高群落多样性增大,均匀度增大。(2)不同海拔群落特征差异主要由气候因子控制,且温度起主导作用,土壤因子的解释度可忽略。(3)整个海拔梯度上群落多样性指数与生物量呈负相关关系,支持根竞争和光竞争假说。

To explore the evolvement pattern of grasslands in humid Tibetan Plateau region and its responses to on-going climate change,we selected the alpine grasslands with different altitudes along the sunny slope of Yajiageng mountain in the eastern Tibetan Plateau,and studied the variation in small-scale characteristics of grassland communities along the elevation gradient,and analyzed the effects of climate and soil variables on community characteristics. Our results showed that aboveground biomass decreased significantly with the altitude increasing,while the underground biomass and the root-shoot ratios of community increased significantly. Community diversity indexes showed significant change between lower altitude sites,but did not change significantly between higher altitude sites. Overall community diversity and evenness increased with the altitude increasing. The variation in community characteristics of different altitudes was mainly controlled by climatic factors,and the temperature played a leading role. The interpretation of the variance from soil factors could be ignored. Community diversity indexes showed negative correlations with aboveground biomass along the elevation gradient,which supports root competition hypothesis and light competition hypothesis.