雅鲁藏布江河岸植物物种丰富度分布格局及其环境解释

Plant species-richness and association with environmental factors in the riparian zone of the Yarlung Zangbo River of Tibet,China

沿环境梯度物种多样性的分布格局及其环境影响因子的研究是生态学研究的重点内容之一。雅鲁藏布江是我国海拔最高的大河,目前还没有针对其流域的河岸植物群落物种丰富度分布格局的系统研究。作者沿海拔梯度从雅鲁藏布江上游源头区至下游共设置了15个海拔样带,在每个海拔样带随机取6个5 m×5 m样方,共对90个样方的河岸植物群落物种组成和植被类型进行了调查,共记录到238种维管束植物。DCA排序结果表明物种组成变化主要受海拔和经度控制。CCA排序区分出5种大的植被类型,即高寒草甸或高寒草原、高山草原、两种亚高山灌丛草原和林缘灌丛植被。各植被类型的分布和变化主要受海拔和经度影响。雅鲁藏布江河岸植物物种丰富度沿海拔和经度梯度呈浅"U"形分布格局,物种丰富度与年均降水量和植被盖度成显著正相关。

Studying patterns of species richness and their causal factors remain important topics in ecology.How species composition,richness and vegetation type change along environmental gradients within the riparian zone of Yarlung Zangbo River have been relatively little studied.Here,a total of 90 plots（6 plots×15 altitudinal transects） were sampled along an altitudinal gradient within this riparian zone.A total of 238 species of vascular plants were recorded,and results of a Detrended Correspondence Analysis indicated that both altitude and longitude play important roles in determining species composition.Canonical Correspondence Analysis showed that the 90 plots could be divided into five vegetation types,and that these vegetation types were affected most by altitude and longitude.We found a slightly inverted U-shaped relationship between species richness and altitude and longitude.Species richness was positively correlated with precipitation and vegetation cover.