基于主成分分析的青藏高原多年冻土区高寒草地土壤质量评价

土壤质量评价是提高对土壤质量理解的关键环节。为了了解青藏高原多年冻土区高寒草地土壤质量的基本情况，在青藏高原腹地西大滩至安多地区，根据不同海拔梯度和植被盖度共采集了154个土壤样品。通过主成分分析（PCA）法确定了影响青藏高原多年冻土区高寒草地土壤质量的最小数据集（MDS）：全氮、全磷、全钾。根据影响土壤质量的最小数据集对青藏高原多年冻土区高寒草地土壤质量进行评价，得出了不同海拔、不同植被盖度下的土壤质量指数（SQI）。通过对不同海拔、不同植被盖度的土壤质量指数进行对比研究表明：随着海拔的升高，SQI呈增加的趋势，即海拔4 300～4 600 m（0.270±0.043） < 海拔4 600～4 900 m（0.326±0.061） < 海拔4 900～5 200 m（0.410±0.075）；随着植被盖度的增加，SQI也呈现增加的变化趋势，即植被盖度小于50%（0.262～0.265） < 植被盖度大于50%（0.336～0.344）。在分别考虑了有机质、盐分、土壤水分对土壤质量的影响下得出的土壤质量指数值与基于最小数据集得到的土壤质量指数相一致，说明基于主成分分析的最小数据集可以对青藏高原多年冻土区高寒草地土壤质量做出较准确的评价。

Soil quality assessment of alpine grassland in permafrost regions of Tibetan Plateau based on principal component analysis

Soil quality assessment is a key step for comprehending soil quality. In order to understand the soil quality of the alpine grassland in permafrost regions of the Tibetan Plateau, 154 soil samples were collected from different altitudes and different vegetation coverages from Xidatan to Anduo in the hinterland of the Plateau. Principal component analysis (PCA) was employed to determine the minimum data set (MDS):total nitrogen, total phosphorus and total potassium, which affected the soil quality on the Plateau. The soil quality of alpine grassland in permafrost region of the Tibetan Plateau was evaluated according to the MDS of soil quality, and the soil quality index (SQI) was obtained under different altitudes and vegetation coverages. The comparative study of the soil quality index under different vegetation coverages and different altitudes showed that SQI increases with increase of vegetation coverage, that is to say, SQI in altitude range of 4 300~4 600 m(0.270±0.043)