中文摘要：

为了阐明高寒草甸退化过程中植物群落物种多样性、生产力与土壤特性的关系,在青藏高原东缘的玛曲县沿着高寒草甸退化梯度选取了轻度退化草甸、中度退化草甸、重度退化草甸和沙化草甸,测定了高寒草甸退化过程中植物群落物种多样性、生产力与土壤理化性状.结果表明：从轻度退化到中度、重度和沙化草甸,植被地下生物量分别降低了36%、48%和91%,总生物量分别降低了34%、47%和91%,土壤有机碳分别下降了18%、81%和97%,全N分别下降了25%、82%和95%,全P含量分别下降了14%、33%和41%.随着高寒草甸的退化,植被群落的生物多样性和地上生物量呈先稳定后降低的趋势,土壤砂粒含量、pH值和全K含量呈增加趋势,黏粉粒呈降低趋势,速效N、速效P和速效K呈先增加后降低的趋势.相关分析表明,群落物种多样性和生产力与土壤有机碳、全N、全P、速效N、速效P、速效K、黏粒含量、粉粒含量、水分含量均呈显著正相关（P〈0.01）,而与土壤砂粒、全K和pH值均呈显著负相关（P〈0.05）.因此,高寒草甸退化过程中,土壤质地、养分和水分等的复杂变化及其相互关系共同决定着高寒草甸群落物种多样性和生产力的变化.同时,植被生产力和土壤碳、氮的降低产生明显的正反馈效应,导致在重度退化阶段和沙化阶段,植被生产力和土壤碳氮的急剧下降.

英文摘要：

To clarify the changes of species diversity and biomass in relation to soil properties of alpine meadows in different degradation stages,mild degraded meadow,moderate degraded meadow,severe degraded meadow and serious sandy meadow were chosen to measure species diversity,biomass and soil properties. The changes of vegetation and soil properties,followed by degraded process of alpine meadow,show the following trends： 1）vegetation diversity and biomass decrease gradually; 2） contents of soil moisture,soil clay,silt,soil organic carbon,total nitrogen（ N）,total phosphorous（ P）,available N and available potassium（ K） decrease consistently,while content of soil sand and total K as well as pH value increase consistently. The correlation between species diversity or biomass and soil factors such as soil moisture,soil clay,silt,soil organic carbon,total N,total N,available N,available P and available K is significant positive,while the correlation between species diversity or biomass and soil factors such as content of soil sand and total K as well as pH value is significant negative. Therefore,changes of species diversity and biomass are governed by soil texture,soil nutrients,soil water content,pH and electrical conductivity.