南亚热带河流底栖硅藻β多样性及其对空间距离与环境梯度的响应——基于广义非相似性模拟的分析

β diversity of benthic diatoms and its responses to spatial distance and environmental gradients in a subtropical river,southern China:GDM based analysis

β多样性指不同生境间群落物种组成的差异,其空间格局及影响因素是生物多样性维持研究的重要内容。以典型的南亚热带中小型河流—广州流溪河为对象,在对底栖硅藻进行季节调查的基础上,采用Baselga对β多样性的分解框架,基于Sørensen相异性系数将底栖硅藻的β多样性分解为周转和嵌套两个组分,运用广义非相似性模拟(Generalized Dissimilarity Modelling,GDM)分析了空间与环境因子对β多样性及其组分的影响。结果表明:底栖硅藻β多样性、物种周转和嵌套组分无明显季节差异,物种周转是流溪河底栖硅藻β多样性的主要组分(>75%);环境与空间过程共同影响流溪河底栖硅藻β多样性和物种周转组分格局,但环境选择是主要的驱动因子;与枯水期相比,丰水期的空间因素对β多样性和物种周转组分的影响程度降低。作为一种非线性距离回归方法,GDM能较好地识别底栖硅藻β多样性及其组分对环境梯度和空间距离的响应。

βdiversity refers to the spatial variation of species composition,and its pattern and the potentially driving factors are important issues of understanding biodiversity.In the present study,we seansonlly investigated benthic diatoms in a subtropical medium river-Liuxihe River in southern China,Guanggzhou,Guangdong Province.In Baselga′s framework partitioningβdiversity,the Sørensen dissimilarities among sampling sites were decomposed into two complementary components:species turnover and nestedness.The relative importance of environmental and spatial processes onβdiversity and its components were explored by using generalized dissimilarity modelling(GDM).The results showed thatβdiversity,and its two components:species turnover and nestedness had no significant seasonality.βdiversity was dominated by species turnover(>75%)in all the four investigated seasons.Both environmental selection and spatial process shaped theβdiversity and its turnover component in Liuxihe River.Environmental selection plays a major role in influencing theβdiversity and its turnover component.The importance of dispersal limitation increased in the dry season compared to that in the wet season.As a distance-based nonlinear regression method,GDM well identified the community variation of benthic diatoms(i.e.,βdiversity)and its two complementary components along both spatial and environmental gradients.