关键词: 高寒草甸, 退化阶段, 生物多样性, 植物功能性状

Abstract: The living state of representative plants and plant community is one of the important indicators for grassland degradation. With a gradient of nondegraded, lightly degraded, moderately degraded, heavily degraded, and extremely degraded alpine meadows in Maqin County, Guoluo Prefecture, Qinghai Province, we analyzed the responses of plant communities, aboveground traits of representative plants and vegetation living state to degradation. Species composition transitioned from Gramineae and Cyperaceae to weeds with intensified degradation. The Shannon diversity index, Simpson dominance index, and Pielou evenness index changed steadily first and then decreased. The community average height and Patrick abundance increased first and then decreased. The total coverage of plant community decreased sequentially. The values of community characteristic indicators were the lowest when communities were extremely degraded (P<0.05). Compared with the lightly degraded plots, plant height of moderately degraded plots, heavily degraded plots, and extremely degraded plots decreased by 6.8%, 36.8%, and 31.6% respectively (P<0.05). The living state index of Kobresia pygmaea gradually decreased. The living state index of Elymus nutans was the highest in moderate degradation. The living state index of Poa orinosa was the highest in light degradation. The living state index of Lancea tibetica was the highest in heavy degradation, while Ligularia virgaurea grew best in the extremely degraded plot. Our results indicated that the degradation of alpine meadows resulted in the changes of community characteristics, the decrease of biodiversity, the decline of living state and dominant position of Cyperaceae and Gramineae, as well as the gradual increase of living state and dominant position of weeds.

Key words: alpine meadow, degradation stage, biodiversity, plant functional trait.