中文摘要：

放牧通过家畜的啃食、践踏、排泄干扰草甸环境，使草甸的物种组成发生改变，植物种群的优势地位发生更替。在样带和样地调查基础上，获取草地群落组成和样地环境数据，通过CCA排序对五台山高、亚高山草甸在经历放牧后的退化状况进行数量化评价，辨识草甸退化的不同等级。结果表明：共划分出5个退化等级，随着退化加剧：①群落环境因子牛马粪数量增加、土壤紧实度加大，土层厚度降低。极度退化草甸与其他4个退化等级之间的环境因子差异显著；②群落数量特征总盖度、生物量、物种丰富度、多样性指数降低，同时一二年生植物所占百分比升高；③放牧干扰草甸的优势种是嵩草、高原嵩草和直梗高山唐松草，轻度干扰草甸中嵩草、高原嵩草（亚高山草甸），珠芽蓼、高山嵩草、发草（高山草甸）为优势种，中度退化草甸高原嵩草依然为优势种，重度和极度干扰草句中优势种被鹅绒委陵菜和平车前取代。放牧已对五台山高山、亚高山草甸群落外貌造成了严重的不良影响，是草甸退化的重要影响因素。为防止草甸资源进一步退化，促进草甸植被恢复，实现资源的可持续利用，建议对中度退化以上草甸采取严格限制家畜数量、分期围封和人工建植乡土植被等措施。

英文摘要：

Wutai Mountain, a high and isolated alpine environment in Shanxi Province in northern China, has numerous subalpine and alpine meadows around its peaks. The alpine meadow zone with diverse meadows has large areas of high-quality grasses suitable for cattle grazing. However, over-grazing in recent years has exerted heavy pressure on the meadow vegetation, leading to serious deterioration in species composition and dominant species succession. This paper, through quantitative analyses of field survey data, describes the grazing impacts on alpine meadow communities and shows the features of degraded meadows under grazing influences, with the goal of improving both the utilization and conservation of the meadow resources. Based on data from 85 quadrats obtained from field investigations using a radial transect, we assessed the degree of degradation of the alpine and subalpine meadow communities under grazing pressure in Wutai Mountain by applying Canonical Correspondence Analysis （CCA）. Comprehensively considering changes in community structure and the corresponding features in environmental conditions by CCA, degradation of the meadow vegetation could be classified into 5 groups： conventional interference, light degradation, medium degradation, heavy degradation and extreme degradation. The results of analysis showed that, along with the aggravating degradation, environmental factors such as animal dung quantity and soil compaction significantly increased, while soil depth decreased. This was especially true for the extreme degradation group. Quantitative features of communities such as coverage, aboveground biomass, species richness and diversity were reduced, whereas the percentage of annual and biannual plants in species composition increased. The dominant species of Kobresia myosuroides, K. pusilla and Thalictrum alpinum under conventional interference were replaced by species of K. myosuroides and K. pusilla （in subalpine meadow） and Polygonum viviparum , K. pygmaea , and Deschampsia caespitosa （in