中文摘要：

通过2年的连续放牧试验,采用比较样地法,调查了不同放牧强度对环青海湖高寒草原生物多样性和生产力的影响,并探讨了植物物种多样性与草地生产力之间的关系,为高寒草原的合理利用提供基础资料。结果表明：物种丰富度和多样性指数随放牧强度的增加基本呈单峰变化,即在中度放牧下多样性最高,重度放牧下群落物种丰富度、多样性指数和均匀度指数均表现为最小;群落生产力随放牧强度的增加而降低（P〈0.05）;莎草科地上生物量差异不显著,禾本科和豆科生产力降低（P〈0.05）,杂类草生物量有增加趋势;禾草和豆科比例减小,莎草和杂类草比例增加;草地生产力与Simpson多样性指数和Alatalo均匀度指数呈显著的单峰函数关系（R2=0.910,P=20.027;R2=0.953,P=20.010）,结合Simpson多样性指数和Alatalo均匀度指数才能更好地反映维持草地生产力水平的多样性指标。放牧强度是影响群落物种多样性和生产力及其关系的重要因素。

英文摘要：

The impact of different grazing intensities on biodiversity and productivity of alpine grassland in Qinghai lake region was investigated using comparative sampling plots.The relationship between plant species diversity and productivity was explored through two years continuous grazing trials.Results showed that species richness and diversity index had a single peak change with the increase of grazing intensity.Species diversity was supreme under moderate grazing intensity.Species richness,diversity index and evenness index were minimum under high grazing intensity.Along with the increase of grazing intensity,community productivity decreased（P0.05）.The aboveground biomass of cyperaceous plant was not significantly different between different grazing intensities,whereas the productivities of gramineous plant and leguminous plant significantly decreased（P0.05）.The yield ratios of both gramineous plant and leguminous plant decreased,whereas the yield ratios of both cyperaceous plant and weeds increased with the increase of grazing intensity.There were significantly unimodal functional relationships between aboveground productivity and Alatalo evenness index,and Simpson diversity index（R2=0.910,P=0.027;R2=0.953,P=0.010）.Therefore,grazing intensity is an important factor to affect species diversity and productivity.