四川卧龙岷江冷杉天然林生物多样性随海拔梯度的响应

Response of Species Diversity in Natural Abies faxoniana Forest Along an Elevation Gradient in Wolong Nature Reserve,Sichuan Province

采用典型样带调查法,在卧龙自然保护区邓生阴坡的岷江冷杉天然林内设置不同海拔梯度的样带,分析岷江冷杉天然林的生物多样性随海拔梯度的响应规律。研究结果表明:岷江冷杉天然林乔木和草本植物的物种丰富度、Shannon-Wiener多样性指数、Pielou均匀度指数和均优丰多样性指数随着海拔升高呈下降趋势,而生态优势度指数呈上升趋势;灌木种随着海拔梯度上升物种丰富度下降,Shannon-Wiener多样性指数、Pielou均匀度指数和均优丰多样性指数则呈现出先降低后升高的趋势,生态优势度指数的变化与之相反;群落所有植物的α多样性随海拔梯度的变化规律与乔木层一致。从β多样性变化来看:随着海拔上升,岷江冷杉林内乔木、草本和所有群落所有植物的相异系数CD和Cody指数均呈下降趋势;而灌木层因为物种数和优势种的改变形成β多样性的双峰变化,这与灌木植物的实际分布是相符的。群落整体的物种差异和更替速率受物种数较多的植被类型影响较大,随海拔升高呈逐渐减小趋势。

Using the typical transect survey method,five sample zones along an elevation gradient were set up in the Abies faxoniana natural forest on the dengsheng shady slope of Wolong nature reserve to analyze the response law of the species biodiversity of Abies faxoniana natural forest with altitude gradients.The results showed that the species richness,Shannon-Wiener diversity index,Pielou evenness index and integrated diversity index of natural Abies faxoniana forest in the tree layer and herb layer showed a decreasing trend with elevation gradient,while the ecological dominance index showed an increasing trend.The species richness of shrub species decreased with the elevation gradient,while the Shannon-Wiener diversity index,Pielou evenness index and integrated diversity index decreased first and then increased,and the variation of ecological dominance index was opposite.Variations ofα-diversity of all plants in the community with elevation were consistent with that of the tree layer.In terms ofβ-diversity,the dissimilarity coefficient CD and Cody index of trees,herbs and all plants in all communities in Abies faxoniana forest showed a downward trend with the rising elevation.However,due to the change of species number and dominant species,the shrub layer formed a bimodal change ofβ-diversity,which was consistent with the actual distribution of shrub species.The species difference and turnover rate of the Abies faxoniana community were greatly influenced by the vegetation types with more species,and gradually decreased with the elevation.