放牧强度对江河源区垂穗披碱草(Elymus natans)/星星草(Puccinellia tenuflora)混播草地群落和高原鼠兔(Ochotona curzoniae)的影响

Effects of Grazing Intensity on Mixed-sown Community of Elymus natans and Puccinellia tenuflora and Ochotona curzoniae in Yangtze and Yellow River Headwater Region

在江河源区披碱草（Elymus natans）／星星草（Puccinellia tenuflora）混播人工草地上进行了两个放牧季（2003年6月29日～9月20日和2004年6月29日～9月20日）的牦牛放牧试验，研究了放牧强度对混播草地群落特征和高原鼠兔（Ochotona curzoniae）种群密度的影响。结果表明：在两个放牧季内，随着放牧强度的提高，草地群落的盖度、地上现存量和优势种植物（披碱草和星星草）的株高降低，且放牧强度与其呈极显著负相关关系；对照处理组群落的物种多样性指数、丰富度指数和均匀度指数最低，中度放牧组最高，该结果支持“中度干扰理论”。随着放牧强度的提高，高原鼠兔的种群密度增加，且放牧强度与其呈极显著的正相关关系；不同放牧强度下群落的物种多样性指数、丰富度指数和均匀度指数与高原鼠兔的种群密度之间存在着一定的相关关系。

This study was conducted in mixed-sown grassland of Elymus natans and Puccinellia tenuflora by 4 yak-grazing intensity gradients and one control in Yangtze and Yellow river headwater re gion for two grazing seasons （from 20th of June to 20th of September in 2003 and 2004） in order to determine the effect of grazing intensity on mixed-sown community and Ochotona curzoniae population density. The result showed that： with the increased grazing intensity during 2 grazing seasons, the coverage of mixed-sown community, standing crop and height of dominance plant （Elymus natans and Puccinellia tenuflora） decreased, and they were significantly and negatively correlated with grazing intensity; plant species diversity, abundance and evenness index was maximized in moderate grazing group, and minimized in control group, which supported ＂intermediate disturbance＂ hypothesis. Moreover, with increasing grazing intensity, Ochotona curzoniae population density increased, and it was significantly and positively correlated with grazing intensity; plant species diversity, abundance and evenness index, to the certain extend, was correlated with Ochotona curzoniae population density under different grazing intensities.