祁连山区退化草地植被群落结构特征的研究

在以针茅和扁穗冰草为优势种的山地草原,由于放牧强度的加大,狼毒的个体数量及其在群落中的作用加强。伴随着狼毒分盖度的增加,针茅和扁穗冰草的地上生物量、密度、盖度和重要值明显下降,毒杂草呈上升趋势。草地的Shannon＿Wiener多样性指数和Pielou均匀度指数随狼毒生物量的增加呈现出由低到高再到低的变化趋势,Simpson优势度指数则呈现出相反的变化趋势;植物群落主要种的优势地位发生了明显的变化,狼毒由伴生种成为优势种,天然草原由禾本科牧草为优势种的顶级群落演替为狼毒为优势种的植被群落。初步提出了恢复该类退化草地生产力水平的对策。

Study on the Vegetation Community's Structure of Degraded Grassland in Qilian Mountains

On the mountain grassland with Stipa krylovii Roshev and Agropyron cristatum Gaertn.as the dominant grass species,vegetation structure has a relative stability.But due to increase of grazing intensity,the composition of different kind plants was changed.As a result,the number of Stellera chamaejasme L increased step by step in the vegetation community.With the increase of the Stellera chamaejasme L.,the out-puts over the ground and the density of the eatable grass such as Stipa krylovii Roshev and Agropyron cristatum Gaertn.decreased.With the increase of the Stellera chamaejasme L,the diversity index Shannon-Wiener and the equality index Pielou were all changed from low to high and then to low again,but the superiority index Simpson took on a opposite trend.At last the dominant grass species of the vegetation community had been changed. Stellera chamaejasme L.changed from minor to major.So the natural grassland had been degraded by the Stellera chamaejasme L.On the basis of the above research,some countermeasures to resume and enhance the production of such degraded grassland were suggested.