青藏高原高寒矮嵩草草甸退化演替主成分分析

摘要

Alpine Kobresia humilis meadows were extensively distributed in Qinghai-Tibetan plateau. The alpine Kobresia humilis meadows were degraded by human disturbing. Using space scale instead of time scale, the plant communities quantity characteristics and soil physical and chemical properties were analyzed at typical alpine Kobresia humilis meadows degradation succession stage. The results showed that, firstly, the alpine Kobresia humilis meadows degradation succession process could be divided into four stages by using Euclidean Distance Clustering method and Fisher's Discriminant Analysis. Fisher's Discriminant Analysis could discriminate the Kobrecia pygmaea community's stage into three phases. So those indexes could be used as index system to divide typical alpine Kobresia humilis meadows degradation succession stages. Secondly, it could draw four principal components (all principal components eigenvalues were grater than 1) by using Principal Component Analysis. All those principal component factors together could explain 97. 6% variance of the sums squared lading. Grassland degradation succession is a process that all factors cooperatively change in the system, and is asynchronism. It also showed that there were two important factors in grassland degradation succession process, one was sensitive factors, which can rapidly change while the grassland ecological system has been changed, another one was buffer factors which play the role in delaying grassland ecological system change. But that how the factors feedback the ecological change and which one is the sensitivity factor, which one is the buffer factor need to be further researched.%选取青藏高原高寒矮嵩草草甸典型退化演替阶段代表样地为研究对象,以空间尺度代替时间尺度的方法,对其植物群落和土壤理化性质(19个指标)进行数量特征分析.结果表明:欧式聚类分析和Fisher's判别分析可以明确划分高寒矮嵩草草甸退化的4个演替阶段,且Fisher's判别分析能够明确区分小嵩草草甸的3个重要时期,说明可以此指标组构建高寒矮嵩草草甸退化演替阶段划分的指标体系.主成分分析(PCA)提取出4个特征值大于1的主成分因子,其载荷能力依次为44.8％、28.3％、17.2％和7.2％,对演替过程总变异的解释能力累计达97.6％.草地退化是一个系统内各因子协同变化的过程,且它们具有不同步性,进而导致了原有变量对草地退化演替细微阶段划分的不完全性.说明草地生态系统存在两种作用因子,即敏感因子(其数量特征随草地发生变化而迅速变化)和缓冲因子(对生态系统变化的反应具有一定的滞后性和缓冲性),但这两者如何应对生态系统干扰,其协同及分异特征以及其对草地退化反应的敏感程度还需要深入研究.