长江源区植物群落特征与环境因子的关系

Relationship between Plant Community and Environmental Factors in the Source Regions of Yangtze River

分析了长江源区冬克玛底流域典型多年冻土区植物群落特征与环境因子的关系.结果表明:1)TWINSPAN将112个植被样方划分为5个主要植物群落,物种生活型组成以多年生草本为主(87种),其次是1～2年生草本(19种);2)植物群落特征与环境特征累计解释量高达88.5%,盖度和生物量对环境梯度变化响应较明显,其次是Patrick、Shannon-Wiener和Simpson指数,而Pielou指数对土壤环境变化响应不明显;3)冻土活动层厚度较小时,土壤有机质和全氮等养分含量较高,植物生物量、盖度及物种多样性较高;反之则具有降低趋势.这说明冬克玛底流域植被盖度、生物量和物种多样性分布格局是各环境因子综合作用的结果,但土壤有机质含量和冻土活动层厚度是影响其变化的关键环境因子.

The relationship between the characteristics of plant community and the environmental factors in the Dongkemadi River basin was studied.The results show that,the 112 vegetation plots were divided into five plant communities by TWINSPAN,and,for the compositions of species life forms,the perennial herbs（87 species） come first and annual or biennial herbs（19 species） second.The cumulative explanation percentage of the biodiversity,biomass,coverage and the environmental characteristics reaches 88.5%.The response of coverage and biomass to environmental factors is most obvious,followed by the indexes of Patrick,Shannon-Wiener and Simpson,and the response of Pielou index to environmental factors is not obvious.When the permafrost active layer is shallow,the soil nutrients such as organic matter and total nitrogen are higher,and the plant biomass,coverage,and species diversity are also larger,and vice versa.These suggest that the distribution patterns of vegetation coverage,biomass,and species diversity in the Dongkemadi River basin are caused by the integrated action of all environmental factors,of which soil organic matter and depth of active layer of permafrost are the two key environmental factors.