为了解植物群落在多尺度下的空间变异规律及其对空间尺度的依赖,以川西南山地阔叶混交林为对象,在有代表性的地段设立100m×100m样地,采用传统的罗盘仪对树体的相对空间位置进行定位,运用主轴邻距法(principal coordinates of neigh...为了解植物群落在多尺度下的空间变异规律及其对空间尺度的依赖,以川西南山地阔叶混交林为对象,在有代表性的地段设立100m×100m样地,采用传统的罗盘仪对树体的相对空间位置进行定位,运用主轴邻距法(principal coordinates of neighbor matrices,PCNM)对群落空间结构的多尺度(100m内)特征进行了研究。结果表明,群落均匀度指数、空隙度和开度、林分胸高断面积和林分密度在大尺度上表现出显著的空间结构。在不同的尺度下,林分密度、叶面积指数和林下地表直接辐射都对均匀度指数有影响,林分密度、林下地表直接辐射、生物量和空隙度都对土壤有机质含量有显著影响,群落结构与环境因子都表现出明显的空间结构。PCNM分析可获取样本间空间关系在不同尺度上的分解向量,与群落结构显著相关的PCNM因子即是群落或生境在该尺度上所表现出的显著的空间结构。典型相关分析结果表明群落结构因子和光因子相关性显著,两者都与PCNM变量极显著相关且相互影响,表明群落结构和光因子都表现出显著的空间结构。因此,利用PCNM对群落结构进行空间分析有助于理解群落空间异质性对尺度的依赖。展开更多
Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evalua...Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.展开更多
文摘为了解植物群落在多尺度下的空间变异规律及其对空间尺度的依赖,以川西南山地阔叶混交林为对象,在有代表性的地段设立100m×100m样地,采用传统的罗盘仪对树体的相对空间位置进行定位,运用主轴邻距法(principal coordinates of neighbor matrices,PCNM)对群落空间结构的多尺度(100m内)特征进行了研究。结果表明,群落均匀度指数、空隙度和开度、林分胸高断面积和林分密度在大尺度上表现出显著的空间结构。在不同的尺度下,林分密度、叶面积指数和林下地表直接辐射都对均匀度指数有影响,林分密度、林下地表直接辐射、生物量和空隙度都对土壤有机质含量有显著影响,群落结构与环境因子都表现出明显的空间结构。PCNM分析可获取样本间空间关系在不同尺度上的分解向量,与群落结构显著相关的PCNM因子即是群落或生境在该尺度上所表现出的显著的空间结构。典型相关分析结果表明群落结构因子和光因子相关性显著,两者都与PCNM变量极显著相关且相互影响,表明群落结构和光因子都表现出显著的空间结构。因此,利用PCNM对群落结构进行空间分析有助于理解群落空间异质性对尺度的依赖。
基金supported by the National Natural Science Foundation of China(31270562 and 31200329)the Chinese Forest Biodiversity Monitoring Network(29200931131101919)
文摘Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.
