关键词: 高寒草甸, 蘑菇圈, 物种组成, 功能群生物量, Raunkiaer频度系数, 演替度, Spearman秩相关

Abstract: Fairy rings is a common ecological phenomenon in alpine meadows on the Qinghai-Tibet Plateau and is an important site for vegetation regeneration. In order to explore the effects of fairy ring formation on vegetation change and community stability in the Plateau’s alpine meadows, we studied the vegetation characteristics of different ring zones, functional group biomass composition by economic category, the life form and succession climax component, the Raunkiaer frequency coefficient, succession degree and Spearman rank correlations within the plant community surrounding the fairy ring zone. The results indicated that: 1) fairy ring formation significantly changed species composition. The dominant species on the fairy ring were Elymus nutans and Aneurolepidium dasystachys but there were no clearly dominant species either within and outside the rings; 2) fairy ring formation significantly increased the biomass ratios of grasses, geophytes and decreaser on the fairy ring, but reduced its species diversity; 3) the community on the fairy ring was at a higher successional stage, and the importance value of plant species accorded with their economic category and succession climax component type’s biomass composition; 4) on the fairy ring, the positive to negative associations ratio of the main species-pairs was 0.89, the interspecific association of most species-pairs was not significant and the community was in a lower stable state; while within and outside the fairy rings the ratios were both >1, the association between most species-pairs was stronger and the community was more stable. The respective associated species-pairs occurred mainly between sub-dominant species or companion species and the companion species of fairy ring communities. This research shows that fairy ring formation can encourage alpine meadow succession from sedges/forbs communities to grass/forbs communities, but that they also reduce the stability of alpine meadows.

Key words: alpine meadow, fairy ring, species composition, functional group biomass, Raunkiaer frequency coefficient, succession degree, Spearman rank correlation