黄河源区沼泽湿地退化过程中植物群落特征的变化

利用空间序列代替时间序列的方法，研究了黄河源区沼泽湿地退化过程中植物群落空间分布特征的变化。结果显示：在湿地退化过程中，经沼泽化草甸、高寒草甸到退化草地，1）群落内物种发生更替，优势种藏嵩草(Kobresia tibetica)逐渐退出群落，多年生杂类草则逐渐增多并演变成优势种；2）物种丰富度、均匀度和多样性指数先升后降，优势度指数先降后升，峰值均出现在高寒草甸阶段；3）群落生产力呈现下降态势，多年生杂类草所占比例随演替年限的增大而急剧增加；4）物种－多度格局由生物统计型的对数正态分布逐渐转变为生态位型的Zipf Mandelbrot分布。

Changes of community characteristics in the degradation process of the alpine swamp wetland in the Yellow River Source area

Based on the method of replacing time series with spatial sequence, the changes of plant community spatial distribution characteristics in the degradation process of the alpine swamp wetland were investigated in the Yellow River Source area in Qinghai Tibetan Plateau of China. The results showed that the degradation process of the wetland experienced from swamp meadow to alpine meadow, and to degraded grassland. During this progress, the species component in plant communities had succession and hygrophytes were replaced by mesophytes and xerophytes, the dominant plants, Kobresia tibetica, gradually disappeared and forbs became constructive species. Species richness index, evenness index and diversity index firstly increased and then decreased whereas dominance index inversely decreased and then increased which peaked at the alpine meadow stage. As the succession proceeded, the above ground biomass showed a unimodal decreased curve, the proportion of perennial forbs increased dramatically and the species abundance distribution gradually changed into a Zipf Mandelbrot model from the early log normal model.