摘要:
等级性的树枝状结构造就了溪流网络中底栖硅藻独特的多样性格局及群落构建方式。于2004年6月对香溪河溪流网络进行底栖硅藻群落及生境调查,选择7个亚流域,在每个亚流域中选择2个干支流汇合点,分别位于河网边缘和河网中心,采用群落分析及β多样性分解的方法,探究树枝状结构中干支流的相互作用及其等级性对底栖硅藻群落及多样性格局的影响。研究结果显示树枝状干支流汇合点上下游之间的栖息地环境、生物密度、物种丰富度、群落组成均不存在显著差异。然而,对位于网络边缘与中心的汇流点上下游进行比较,发现树枝状结构在群落构建中的作用具有等级性。河网边缘与中心的干支流群落β多样性组分存在显著的差异:在河网边缘,β多样性的周转组分显著高于河网中心,因此,河网边缘的干支流群落格局主要受物种在干支流间的物种周转所影响;河网中心β多样性的嵌套组分更高,这说明群落格局更多由干支流间物种的增减所造成。
Abstract:
The hierarchical dendritic structure of stream network created unique diversity patterns and community assembly of benthic diatoms. Aiming at exploring the effects of interaction between mainstream and tributary and its hierarchy on benthic diatom community and diversity patterns in a dendritic stream network, we investigated 7 sub-basin in Xiangxi River network, and selected two confluences (one located in peripheral and the other one in central position of the network) in each sub-basin, where diatoms and habitat samples were collected on the upstream and downstream of each in June 2004, and then a series of community analyses and β-diversity partitioning were performed. The results showed that there were no significant differences in habitat conditions, density of diatoms, species richness and species composition between upstream and downstream of confluences both in peripheral and central position of the network. However, comparing upstream and downstream of confluences between peripheral and central position of the network, hierarchy of dendritic stream network was found in community assembly. There was significant differences in β diversity components between peripheral and central confluences:for peripheral confluences, β diversity were influenced by species turnover between tributary and mainstream; and for central confluences, β diversity patterns were resulted from the loss and gain of species between tributary and mainstream.
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