| Summary: | Understanding the role of dominant species in structuring the distribution of neighbor species is an important part of understanding community assembly, a central goal of ecology. Phylogenetic information helps resolve the multitude of processes driving community assembly and the importance of evolution in the assembly process. In this study, we classified species in a 20-ha subtropical forest in southern China into groups with different degrees of phylogenetic relatedness to the dominant species <i>Castanopsis chinensis</i>. Species surrounding individuals of <i>C. chinensis</i> were sampled in an equal area annulus at six spatial scales, counting the percent of relatives and comparing this to permutation tests of a null model and variance among species groups. The results demonstrated that dominant species affected their relatives depending on community successional stage. Theory would predict that competitive exclusion and density-dependence mechanisms should lead to neighbors that are more distant in phylogeny from <i>C. chinensis</i>. However, in mature forests distant relatives were subjected to competitive repulsion by <i>C. chinensis</i>, while environment filtering led to fewer distant species, regardless of scale. A variety of biological and non-biological factors appear to result in a U-shaped quantitative distribution determined by the dominant species <i>C. chinensis</i>. Scale effects also influenced the dominant species. As a dominant species, <i>C. chinensis</i> played an important role in structuring the species distributions and coexistence of neighbor species in a subtropical forest.
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