华北区域环境梯度上阔叶林构建模式及分布成因

Community assembly, diversity patterns and distributions of broad-leaved forests in North China

森林群落的构建即多样性维持机制是当今生态学研究的热点问题。然而,当前群落构建和群落多样性的研究多在间接梯度上进行,而在水、热等影响物种在区域内定植的关键且直接的环境梯度上研究群落构建和多样性模式则鲜有报道。结合环境因子,基于物种组成和谱系方法探讨不同群落的分布成因,有助于解释群落构建过程中的关键问题。该研究基于华北森林群落调查数据和环境数据,涉及7个省市区的29个以壳斗科、桦木科为优势种的群落,探讨了直接环境梯度上的群落构建和多样性模式,同时用典范对应分析研究了不同群落分布的环境解释。结果发现,相似的群落具有相似的生境偏好,相似的生境条件会形成物种组成相同或相似的群落。环境热量主导了本区域的谱系关系,在年平均气温较低的地区,群落构建主要表现为生境过滤的模式。此外,随着年降水量的增加,生境过滤作用逐渐增加。在温度梯度上,谱系多样性表现为钟形模式,而降水量的增加能导致谱系多样性的增加。

Aims To understand the key processes driving the community assembly and diversity patterns in North China.Methods We investigated species composition of 87 plots from 29 sites.We applied phylogenetic approach,combined with community distribution information,to assess the community structure and diversity along environmental gradients.We then performed a variance partition to explore the relative importance of each environmental factor that influencing the patterns of community assembly and diversity process and a canonical correspondence analysis to analyze reason of community distributions.Important findings Similar communities showed similar habitat preferences,demonstrating that environments may shape species composition of the communities.The phylogenetic diversity showed a uni-modal pattern with the mean annual temperature(MAT),but increased with the mean annual precipitation(MAP),partly because of the strong disturbance in high-MAT regions.Temperature dominated the phylogenetic structure of the broadleaved forests in North China.Environmental filtering dominate the community assembly processes in the areas with relatively low MAT.In addition,the effect of environment filtering increased with MAP.