黄河源头高寒草原植被退化特征分析

Feature analysis of vegetation degradation on Alpine Grassland in Yellow River source region

以紫花针茅Stipapurpurea ,早熟禾Poaannua为优势植被的高寒草原是黄河源头区典型植被类型之一。由于自然环境变迁以及人为活动的影响 ,黄河源头以扎陵湖北岸地区为中心的紫花针茅草原和早熟禾草原植被退化十分明显 ,2 0 0 2年通过样方调查和植被数量分析的方法 ,对该地区的退化草地特征进行了系统的调查和分析 ,结果表明 :退化草地植被盖度比未退化区下降 10 %～ 5 5 % ;优势物种变化 ,紫花针茅、早熟禾等植物种生长势减弱 ,物候期推迟 ,群落优势植物逐步演替为以菊科、豆科等杂类草植物为优势种的群落 ;物种多样性指数下降 5 5 %～ 79%。由于高寒植被的退化 ,导致了植被群落整体生态功能的下降 。

Alpine grassland and alpine meadow is the main steppe vegetation in Yellow River source region, of which Stipa purpurea var. arenopsa and Poa annua are dominant and typical. Under the effect of human activity, the Stipa purpurea var. arenopsa was clearly degenerated. In 2002, we used the vegetation quality method to analyze the succession process of alpine steppe vegetation. The results showed that in degenerated vegetation region, the percentage of community coverage and indexes of biodiversity decreased 10%～55% and 55%～79%, respectively, compared with the primitive vegetation. At the same time, dominant vegetation was also clearly changed, the growth potential of Stipa purpurea var. arenopsa and Poa annua decreased, composite and legume plants became the dominant species. Because of the degenerated vegetation, the ecological function of the community vegetation declined, which further led to the ecological environment deterioration.