Relationships of Rumex nepalensis distribution and plant species diversity ofalpine rangeland in northwestern Yunnan Province

The spatial distribution of 4 different kinds of Rumex nepalensis cover community in Sewalongba Valley, an important alpine summer rangeland in Dimaluo village, Gongshan County，northwest Yunnan Province, were investigated with the point quatrats in September 2009; their community diversity and species diversity were analyzed by Shannons Diversity Index (H) and Equitability (evenness) (EH). The research found that there were 25 species within the study plots. The cover of Rumex was positively correlated with Carex inanis and Potentilla leuconota, whereas it was negative correlated with Galium aparine var. echinospermu Cufodontis and Oenanthe sinense. The moderate and moderate high Rumex areas had the highest species richness and diversity and high species evenness, followed by the high Rumex areas. The lowest species richness and diversity was in the low Rumex sites, but it had the highest total species density. These results indicated that the effect of Rumex on plant species diversity is not quite so clear, and the main reasons for the rangeland plant diversity losses are the grazing intensity and frequency.