祁连山东段干旱草原2种群落物种构成及稳定性研究

Research on the Vegetation Composition and Community Stability of Arid Grassland in the East of Qilian Mountains

芨芨草作为干旱、半干旱草原建群种,其群落植被构成和稳定性影响草原荒漠化程度,研究其群落物种构成及稳定性,可表征草原演替动态和发展方向。该研究以甘肃天祝松山滩干旱草原芨芨草群落和针茅群落为对象,定量分析其群落物种组成和多样性、功能群生物量构成、Raunkiaer频度和种间Spearman秩相关,探究物种构成和种间关联与群落稳定性的关系。结果表明:(1)针茅群落物种多样性较芨芨草群落丰富,其物种更替程度相近。(2)2个群落均处于退化状态,随退化程度加剧,丛生禾草和杂类草分别占据芨芨草群落和针茅群落主要地位。(3)2个群落主要植物种对的正负关联比皆小于1,其植物种间联结性松散,群落稳定性较低。(4)高物种多样性不利于针茅群落稳定。研究认为,群落功能群构成及其均匀度和干旱扰动比多样性对群落稳定性影响更大。

Achnatherum splendens is a constructive species in arid or semi-arid grassland, vegetation composition and community stability of its community can affect the desertifieation degree of grassland, which represents successional dynamics and development direction of community. The aims of this study is to ex- plore the relationship between vegetation composition, interspecific association and community stability by analyzing the composition, and diversity of species, functional group biomass composition, Raunkiaer fre- quency coefficient, and Spearman rank correlation of A. splendens and Stipa communities in Songshantan grassland in Gansu Tianzhu. The results indicated that, （1） the species diversity of Stipa community was richer than that of A. splendens community,and the degree of species replacement was similar in these two communities. （2） The two communities were degraded, with the grassland degradation increased, A. splendens and Stipa communities dominated by grasses and forbs, respectively. （3） The positive to nega- tive association ratio of species-pairs in two communities was less than one, and the interspecific associa- tion was loose, and they had a low community stability. （4） The high species diversity was not benefit for the stability of Stipa community. The study suggests that biomass composition of functional group, even- ness of species and drought disturbance had higher effects on the community stability than that of the species diversity.