东祁连山高寒杜鹃灌丛群落结构和物种多样性对海拔梯度的响应

Structure and species diversity of alpine Rhododendronshrub-herb community and its response to altitudegradients in eastern Qilian Mountains

摘要:

以东祁连山不同海拔梯度(3 030 ~3 280 m)高寒杜鹃灌丛草地为研究对象,探讨高寒杜鹃灌丛灌下草本。灌木及其灌丛植物群落特征和物种多样性在垂直梯度上的变化规律。结果表明:高寒杜鹃灌丛灌木高度,密度和生物量均随海拔升高呈先增加后降低的单峰变化趋势,在海拔3 130 m达最高。灌下草本高度随海拔升高呈先增加后降低的单峰变化趋势,在海拔3 080 m处达最高。灌丛群落总地上生物量随海拔升高呈先显著增加后显著降低的变化趋势,在海拔3 130 m处达最高。灌下草本,灌木和灌丛群落的Shannon-Wiener多样性指数和丰富度指数均随海拔升高呈先增加后减小的变化趋势,最大值均出现在海拔3 080 m处。在调查海拔范围内,草本,灌木和灌丛群落的Shannon-Wiener指数,草本均匀度指数、灌丛群落丰富度指数均和海拔呈显著负相关,灌木丰富度指数和灌丛群落均匀度指数与海拔呈显著正相关,草本和灌丛群落Shannon-Wiener指数与地上生物量呈显著正相关。因此,中海拔区域(3 080~3 130 m)物种多样性丰富,生产力较高。

Abstract:

The variation of height,coverage,density,aboveground biomass and diversity of Rhododendron shrub-herb communities along an altitude gradient (from 3 030 m to 3 280 m) was studied in the eastern Qilian Mountains on the Qinghai-Tibetan Plateau.The results showed that the height,density and aboveground biomass of shrub showed a curvilinear change with altitude increasing,and reached the highest at 3 130 m.The height of herbs showed a curvilinear change with altitude increasing,and reached the highest at 3 080 m,while the coverage,density and biomass of herbs decreased with the increase of altitude.And the coverage and density of the shrub-herb communities decreased with the increase of altitude,while the total biomass first increased and then decreased significantly with the increase of altitude,and reached the highest at 3 130 m.The Shannon-wiener index and richness index of herbs,shrubs and communities initially increased and then decreased with altitude increasing and the highest value appeared at 3 080 m.At altitude of 3 080 to 3 130 m,Shannon Wiener index of herbs,shrubs and community,and the evenness index of herbs,and the richness index of community were significantly negatively correlated with altitude,and the evenness index of community and the richness index of the shrubs showed significant positive correlation.The Shannon-wiener index of and shrub-herb community showed significant positive correlation with the aboveground biomass.Therefore,the shrub-herb community possessed abundant species and higher productivity in middle elevation (3 080 to 3 130 m) area.