Effects of Over Grazing on Plant Species Diversity of Alpine Kobresia (Kobresia Pygmaea) Meadow in Tibet
With the persistent increase of livestock the Alpine kobresia meadow has suffered from intensive grazing and had led to the wide-spread degradation of grasslands in Nagqu prefecture, Tibet. In this study, according to the actual grazing densities and grazing capacity of un-grazing grassland, the study area was divided into three over-grazing gradient (extremely over-grazing, highly over-grazing, medium over- grazing) and a enclosure Plot along the grazing route. Census in total 20 samples has shown the results as follows: (1) The ratio of area of EOG, HOG, and MOG came at 9.02％, 25.4％, and 65.58％, respectively, and a average over-grazing ratio in study area was 131.47 per cent. (2) The composition and structure of Alpine kobresia meadow in over- grazing differed significantly with UG, the more intensity of grazing pressure, the more simple kind of structure, the Kobresia pygmaea and species of Grass family are absolute dominant species in the over-grazing sites and in the un-grazing grasslands, respectively. (3) The grassland UG had significantly greater mean number of species, Richness index values, Shannon-Wiener index values, and Evenness index values than three over-grazing sites, but had significantly lower greater Simpson index than over- grazing sites. The grassland EOG had significantly lower mean number of species and Richness index values but it had significantly lower Simpson index than both of HOG and MOG. The grasslands EOG and HOG had significantly greater Shannon-Wiener index than grassland MOG (4) The grassland UG had significantly higher cover percentage than over-grazing grasslands, the MOG had more than both of HOG and EOG, and HOG had more than EOG; the over-grazing grasslands had significantly lower dry matter weight than the grassland UG It suggested that prohibit to the increase of livestock, contract the pasture resources to families, extend to the technique of grazing rotation and return the animal manure to grasslands are essential for increase the biodiversity of Alpine kobresia meadow.
diversity over-grazing alpine kobresia meadow Tibet
WEI Xinghu YANG Ping LI Sen DONG Yuxiang ZHANG Chunlai
Department of Resources and Environmental of Foshan University, Foshan 528000, Guangdong, China Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Science, Department of Geography of Zhongshan University, Guangzhou 510275, Guangdong, China Beijing Normal University, Beijing 100875, China
国际会议
2007年中国科协科技年会(The Annual Conference of the China Association for Science and Technology)
武汉
英文
190-197
2007-09-08（万方平台首次上网日期，不代表论文的发表时间）