水淹干扰下水库水滨带植物群落谱系结构与物种多样性格局

Phylogenetic structure and species diversity pattern of plant community under flooding disturbance in the riparian zone of reservoir

群落谱系结构将物种系统发育信息整合到群落中,给生物多样性研究提供了全新视角。为探讨水淹干扰下水库水滨带植物群落物种多样性维持机制,以丹江口水库水滨带为研究区域,以南水北调中线一期工程运行前的原有水滨带植被为研究对象,分析不同水淹干扰强度下群落谱系结构和物种多样性及其与环境因素的关系。结果表明:(1)随着水淹干扰强度增加,群落物种丰富度、物种多样性和谱系多样性显著降低。谱系结构指数虽无显著差异,但随着水淹干扰强度增加呈现由发散到聚集的变化趋势。表明水滨带植物群落物种多样性维持机制是生境过滤和生态位分化共同驱动的结果,并且随着水淹干扰强度增加呈现生境过滤作用增加、物种间竞争排斥作用减弱的生态过程影响规律。(2)坡度、土壤质地、速效氮和全氮含量对整个水滨带植物群落物种丰富度、物种多样性和谱系多样性影响显著。此外,土层厚度和速效磷对物种丰富度和土层厚度对谱系多样性也影响显著。而仅有速效氮含量对谱系结构指数影响显著;轻度水淹干扰下坡向、速效磷含量与多样性指数显著相关;中度水淹干扰下坡度、土层厚度、土壤质地、土壤总氮含量与多样性指数显著相关,土壤pH、全氮和全磷含量与谱系结构指数显著相关;重度水淹干扰下土壤质地、土壤全氮和速效氮含量与多样性指数显著相关。结果表明不同水淹干扰强度下的水滨带环境异质性导致了植物群落物种多样性维持机制的差异。研究结果可为水库水滨带生物多样性保护提供理论依据。

Phylogenetic structure incorporating phylogenetic data in the studies of community provides a new perspective for biodiversity research.To explore the maintenance mechanisms of species diversity of riparian plant communities under the flooding disturbance,the original riparian vegetation in Danjiangkou Reservoir before the first phase of the Middle Route of the South-to-North Water Diversion Project was investigated.The phylogenetic structure and species diversity of riparian communities and their relationship with environmental factors under the flooding disturbance were analyzed.The results indicated that:(1)with the increase of the intensity of flooding disturbance,the species richness,species diversity,and phylogenetic diversity of the riparian communities decreased significantly.Although there was no significant difference in the net relatedness index of communities,the phylogenetic structure communities showed a trend from divergence to aggregation with the increase of flooding disturbance intensity.The results indicated that the maintenance mechanism of species diversity in the riparian plant community was driven by habitat filtration and niche differentiation.And the ecological process effect of habitat filtering increased and the competition between species weakened with the increase of flooding disturbance intensity.(2)The species richness,species diversity,and phylogenetic diversity of all plant communities in the riparian zone were significantly affected by slope,soil texture,available nitrogen content,and total nitrogen content.In addition,the species richness was significantly affected by soil thickness and available phosphorus content,and the phylogenetic diversity was significantly affected by soil thickness.However,only available nitrogen content had a significant effect on the net relatedness index.Slope aspect,available phosphorus content,and the three diversity indices were significantly correlated under the light flooding disturbance.Slope,soil thickness,soil texture,total nitrogen content,and three diversity indices were significantly correlated,and soil pH,total nitrogen content,available phosphorus content,and net relatedness index were significantly correlated under the moderate flooding disturbance.Soil texture,available nitrogen content,total nitrogen content,and the three diversity indices were significantly correlated.The environmental heterogeneity under different flooding disturbance intensities resulted in different mechanisms of community construction and diversity maintenance in riparian zones.The study provides the theoretical reference and a scientific basis for biodiversity conservation in the riparian zone of the reservoirs.