三峡水库澎溪河消落带植物群落物种丰富度格局

通过样地调查和Spearman相关分析，研究了澎溪河消落带植物群落物种丰富度格局. 结果表明:沿河流纵向梯度，总物种丰富度、灌木层和草本层物种丰富度均表现出抛物线型，乔木层物种丰富度表现出直线型；沿河流侧向梯度，总物种丰富度和草本层物种丰富度随高程的增加先升高后降低；乔木层和灌木层物种丰富度随高程的升高而增加. 在纵向梯度上，底质类型与物种丰富度显著相关，距河口的空间距离对物种丰富度有重要的控制作用；在侧向梯度上，淹水时间、土壤含水量、底质异质性对群落空间格局有重要影响. 总体来说，消落带植物物种丰富度格局仍受原河流地貌及洪水格局的影响，但由于水位季节性变动，已形成与水位变动相适应的分布格局. 

Patterns of Plant Community Species Richness in the Fluctuating Water Level Zone along the Pengxihe River of the Three Gorges Reservoir

The spatial pattern of plant community species richness in the fluctuating water level zone along the Pengxihe River of the Three Gorges Reservoir was studied by sample-plot survey and Spearman correlation analysis. The results showed that along the longitudinal gradient, species richness, longitudinal shrub species richness and longitudinal herb species richness showed significant quadratic relationships with distance to the estuary along the river, while longitudinal tree species richness exhibited a linear relationship with distance to the estuary along the river. Along the lateral gradient, species richness and herb species richness increased first and then decreased along with elevation, while tree and shrub species richness increased with elevation. Correlation analysis showed that along the longitudinal gradient, significant positive correlation existed between species richness and substrate types, and distance to the estuary was critical in the control of species richness. Along the lateral gradient, submergence time, soil moisture and substrate heterogeneity had important impacts on spatial pattern of species richness. On the whole, the pattern of plant species richness in the fluctuating water level zone was still influenced by fluvial geomorphology and flood pulse, but had gradually formed with seasonal water level fluctuation of the Three Gorges Reservoir.