Abstract: Alpine grassland of Qiangtang in northern Tibet was selected to study the effects of grassland degradation on plant community structure and reproductive allocation of 16 species in this paper. Results showed that the dominant plant communities changed significantly and the indicators of community structure decreased with the degree of grassland degradation increasing. The degradation degree significantly affected both individual species biomass and allocation of most species biomass. The absolute reproduction input was affected insignificantly, whereas the reproductive allocation was increased significantly with the degree of grassland degradation increasing. Plant reproductive allocation was increased, whereas both stem and leaf allocations were decreased in community levels. Species within the same plant community affected differently by different degradation degrees indicated that the reproductive allocation was related with degradation degrees and reflected the plasticity of plant reproductive strategies and reproductive characteristics in the life cycle.

Key words: Degradation, Alpine meadow, Plant communities, Community structure, Reproductive allocation

摘要： 以西藏北部羌塘草原高寒草甸为研究对象,研究不同退化阶段草地植物群落特征及16种主要组分种的繁殖分配,试图揭示多年生草本植物及其繁殖分配与草地退化程度的关系。结果表明:随着退化程度的加剧高寒草甸植物群落内优势植物发生明显变化,草地群落的各项指标随着草地退化程度的增加而降低;退化程度对群落内物种个体生物量大小和生物量分配有着显著影响,伴随退化程度的加剧各物种对繁殖的绝对投入所受影响不明显,但繁殖投入升高。在群落水平上,草地退化使植物群落繁殖分配增加,茎分配和叶分配减少。不同植物群落内共有种繁殖分配存在差异,表明其繁殖分配跟退化程度有关;植物繁殖投入随退化程度的变化,反映了植物繁殖对策和繁殖投入在生活史特征中的可塑性。

关键词: 藏北, 退化程度, 高寒草甸, 植物群落, 群落特征, 繁殖分配