长江源区紫花针茅草原群落数量分类与排序

选择长江源地区典型的紫花针茅草原作为研究对象，以大量的群落学样方调查为基础，采用TWINS-PAN、DCA、物种多样性，相关分析等多元数量分析方法，系统研究了紫花针茅草原的群落特征、物种多样性、群落与环境因子的关系.结果表明：(1)所调查的紫花针茅草原是物种组成相对简单、菊科和禾本科植物最多、北温带分布属为主体的草原群落；(2)长江源区紫花针茅草原群落可划分为四个群丛类型：紫花针茅＋密丛棘豆群丛，紫花针茅＋梭罗草群丛，紫花针茅＋伊凡苔草群丛，紫花针茅＋弱小火绒草群丛；(3)影响群丛分布的主要环境因子首先是海拔、经纬度等空间因子，其次是湿润度、降雨量等水分因子的影响；(4)紫花针茅＋伊凡苔草群丛的物种多样性是研究区四个群丛中最高的.Simpson指数和均匀度指数受海拔、经纬度、平均降雨量、均湿润度等环境因子影响显著.该研究揭示了紫花针茅草原群落的内在规律.

Quantitative classification and ordination of Stipa purpurea steppe community in source region of the Yangtze River

The typical Stipa purpurea steppe in the source region of the Yangtze River was selected as subject. Multivariate statistics methods including TWINSPAN, DCA and correlation analysis were used to calculate the data on the basis of investigating a large number of vegetation communities in this region, in order to investigate the community characteristics, community diversity, and the relationship between community and environment factors. The results were as follows:(1)The species composition of S. purpurea steppe in the study area was relatively simple. The dominant families of seed plants were Gramineae and Compositoe, and the dominant areal types of genera were North temperate type;(2)The S. purpurea steppe community in the source region of the Yangtze River could be classified into 4 ecological associations:Ass. Stipa purpurea + Oxytropis densa, Ass. Stipa purpurea + Kengyilia thoroldia, Ass. Stipa purpurea + Carex ivanovae and Ass. Stipa purpurea + Leontopodium humilum;(3)The major environmental factors influenced the distribution of Stipa purpurea steppe ecological associations in source region of the Yangtze River firstly were space factors(altitude, longitude and latitude), then water factors(precipitation, wetness);(4)Ass. Stipa purpurea + Carex ivanovae hold the three highest indexes of the 4 ecological associations in the study area. Both evenness index and Simpson index were influenced by space factors and water factors. The present study proclaim the inner ecological rules of Stipa purpurea steppe in source region of the Yangtze River,and will play a very important role in maintaining the ecosystem equilibrium of ecologically fragile zones