不同放牧强度对高寒草甸植被群落结构和土壤理化性状的影响

放牧是青藏高原高寒草甸最基本的利用方式。高寒草甸生态系统能否可持续利用与放牧强度紧密相关。本研究通过在青藏高原东缘碌曲县设置三个放牧强度处理和一个对照，分析了植被群落结构和土壤理化性质对放牧强度的响应。结果表明，植被盖度、高度和地上生物量均随放牧强度增加而降低，物种丰富的在中度放牧下最高；适度放牧能显著增加莎草比例，杂草随放牧强度增加而增加；土壤含水量和有机质随放牧强度增加而降低，pH和全磷无显著性变化，土壤容重无规律性变化；全氮、全钾和速效钾随放牧强度增加呈先增加后降低的趋势；速效磷随放牧强度增加而增加。综合分析认为，适度放牧能显著改良植被群落结构和土壤理化性质，有利于高寒草甸的可持续利用。

Effects of Different Grazing Intensities on Vegetation Community Structure and Soil Physical and Chemical Properties in Alpine Meadow

Grazing is the most basic utilization method of alpine meadows on the Qinghai Tibet Plateau. The sustainable use of alpine meadow ecosystem is closely related to the intensity of grazing. In this study, three grazing intensity treatments and one control were set up in Luqu County on the eastern edge of the Qinghai Tibet Plateau, and the responses of vegetation community structure and soil physical and chemical properties to grazing intensity were analyzed. The results showed that vegetation cover, height and aboveground biomass all decreased with the increase of grazing intensity. Species richness was highest under moderate grazing. Moderate grazing can significantly increase the proportion of sedge. Weeds increased with grazing intensity. Soil water content and organic matter decreased with the increase of grazing intensity. There was no significant change in pH and total phosphorus, and the soil bulk density changed irregularly. Total nitrogen, total potassium and available potassium increased first and then decreased with the increase of grazing intensity. Available phosphorus increased with the increase of grazing intensity. According to the comprehensive analysis, moderate grazing can significantly improve the vegetation community structure and soil physical and chemical properties, which is beneficial to the sustainable use of alpine meadows.