不同退化程度高寒草地植物群落与土壤性质变化及相关性分析

为探究退化高寒草地植物群落组成及土壤性质的变化规律，本研究选择铁卜加、河南县不同退化程度高寒草地为研究对象，对轻、中、重度退化高寒草地的植物群落结构组成和土壤理化性质进行了分析研究。结果表明：随退化程度加剧，植被群落优势种由莎草科为主逐渐转变为杂类草为主；植被高度、盖度、地上-地下生物量逐渐减小；Patrick指数、Shannon-Wiener指数、Simpson多样性指数与Pielou指数呈先增后减趋势；土壤含水量、全碳、有机碳、硝态氮含量明显减小且土壤pH值逐渐偏弱碱性，促使土壤养分含量不断流失，贫瘠化加剧；经相关系数矩阵图分析，退化草地群落植被生物量受土壤含水率和氮含量变化影响较为严重。总之，高寒草地退化接替过程中，杂类草逐渐占植物群落组成的主导地位，土壤含水率和氮含量变化是致使这2个地方草地退化的关键性因子。

Characteristics and Interrelationship of Plant Community and Soil Properties in different Degraded Alpine Grasslands

To explore the change rule of plant community composition and soil properties in degraded alpine grasslands,this study selected alpine grasslands with different degradation degrees in Tiebuga and Henan counties as research objects,and analyzed the plant community composition and soil physical and chemical properties of light,medium,and severe degraded alpine grasslands. The results showed that the dominant species of vegetation community gradually changed from sedge to forbs with the aggravation of degradation. Vegetation height,coverage,and both above andbelow ground biomass decreased. Patrick index,Shannon-Wiener index,Simpson diversity index,and Pielou index increased first and then decreased. Soil moisture,total carbon,organic carbon,and nitrate nitrogen decreased significantly,and soil pH value gradually turned weak alkaline,which led to continuous loss of soil nutrient content and the intensification of barrenness. By analysis of the correlation plot,the vegetation biomass of the degraded grassland community was seriously affected by the changes in soil moisture content and nitrogen content. In brief,in the process of alpine grassland degradation,Forbs gradually dominate the composition of the plant community,and changes in soil moisture content and nitrogen content are the key factors causing grassland degradation in two regions.