Abstract: Land desertification is one of the important ecological problems in the Qinghai Lake basin,and the evolution characteristics of plant communities at different desertification stages is helpful for desertification control in this region. In this study,we conducted the field survey,and investigated the dynamic patterns of plant composition at potential,slight,moderate,heavy,and severe desertification stages,based on the ANOVA,principal component,and correlation analysis. The results showed that with increasing desertification degrees,the dominant species in the plant community changed from mesophytes of Kobresia humilis,Poa pratensis,and Elymus nutans to xerophytes of Orinus kokonorica,Krascheninnikovia ceratoides,and Artemisia desertorum. Meanwhile,plant coverage,height,aboveground biomass and abundance decreased with increasing desertification degrees. Species richness,Shannon-Wiener,Simpson,and Pielou index all increased first and then decreased,with the highest at moderate desertification stage,which was consistent with "intermediate disturbance hypothesis". The diversity index were ordered for impact of desertification process,i.e.,Shannon-wiener>Species richness>Simpson>Pielou,and all the diversity indexes were significantly correlated with vegetation characteristics,except for Pielou index. The results provided a basis for the studies on desertification control and community diversity in Qinghai Lake basin.

Key words: Qinghai Lake basin, Plant community, Diversity, Desertification

摘要： 土地沙漠化是青海湖流域重要的生态问题之一，明晰区域内不同沙化阶段植物群落的演化特征，有助于为该区沙漠化防治工作有效开展提供科学依据。本研究通过野外样方调查并应用方差分析、主成分分析和相关性分析，厘清该区潜在、轻度、中度、重度和极重度沙化阶段植物组成特征与变化规律。结果表明，随沙化程度加剧，植物优势种从矮生嵩草、草地早熟禾和垂穗披碱草演替为青海固沙草、驼绒藜和沙蒿，生活型从中生向旱生演替；植物盖度、高度、地上生物量和多度依次降低；物种丰富度、Shannon-Wiener指数、Simpson指数与Pielou指数均为先升后降，轻度沙化阶段最高，符合“中度干扰假说”。沙化过程对多样性指数影响为Shannon-Wiener指数>物种丰富度>Simpson指数>Pielou指数，除Pielou指数外，其余多样性指数与植被特征相关性显著。研究结果可为青海湖流域沙化防治及群落多样性研究提供参考。

关键词: 青海湖流域, 植物群落, 多样性, 沙化