Abstract: Biological soil crust (biological crust) is an important surface covering of degraded alpine grassland,which has the function of regulating soil nutrient cycling and affecting plant community structure and characteristics. In this study,the biological crust of different coverage,herbaceous plant community and soil chemical properties were studied. In July 2018,the experimental investigation and sampling were carried out in the alpine grassland of Guinan County,Qinghai Province. The results showed that the change of the coverage of biological crust significantly affected the structure of herbaceous communities,and reduced the proportion of grasses and the average height of plant communities (P<0.05). There was an extremely significant negative correlation between biocrust coverage and soil pH (P<0.01),an extremely significant positive correlation between biocrust coverage and soil total nitrogen content (P<0.01),and a significant positive correlation between biocrust coverage and soil organic carbon content (P<0.05). It indicated that the existence and coverage change of biological crust significantly affected the herbaceous community and soil nutrient cycle of alpine grassland,and might play an important role in the management of alpine grassland degradation.

Key words: Alpine grassland, Biological crust, Coverage, Community structure, Soil chemical properties

摘要： 生物土壤结皮（生物结皮）是退化高寒草地重要的地表覆盖物，它具有调控土壤养分循环和影响植物群落结构和特征的作用。本研究以不同盖度生物结皮、草本植物群落和土壤化学性质为研究对象，于2018年7月份在青海省贵南县高寒草地展开试验调查和取样。结果表明：生物结皮盖度的变化显著影响了草本植物群落的结构，降低了禾本科植物的比例和植物群落的平均高度（P<0.05）；生物结皮盖度与土壤酸碱度呈极显著的负相关关系（P<0.01），与土壤全氮含量呈极显著的正相关关系（P<0.01），与土壤有机碳含量呈显著的正相关关系（P<0.05）。可见，生物结皮的存在和盖度变化会显著影响高寒草地草本植物群落和土壤养分循环，在高寒草地退化问题的治理中可能扮演着重要的角色。

关键词: 高寒草地, 生物结皮, 盖度, 群落结构, 土壤化学性质