Leaf stomatal and anatomical traits facilitate the coexistence of dominant plant species during succession in a subtropical broad-leaved forest

Forest degradation is a serious global-scale environmental issue which caused the loss of biodiversity in subtropical broad-leaved forests. Though more studies focus on forest succession, understanding the patterns in variations of leaf tissue structure is essential for the restoration of secondary forest communities. In this study, we compared the stomatal properties and leaf anatomical traits of plants from different succession stages of communities in a subtropical broad-leaved forest. Results showed that most of the leaf functional traits varied apparently across different succession communities, with low trait variations in narrowly distributed species and higher trait CV in those that occurred in two or more communities. Shrubs and most of the small trees from grassland and shrub-grassland displayed significant higher leaf thickness, palisade mesophyll thickness, leaf palisade: spongy mesophyll thickness ratio, tightness of leaf palisade tissue. In contrast, many trees in primary forest possessed the lowest leaf thickness, stomatal density, potential conductance index, adaxial epidermis thickness, leaf palisade: spongy mesophyll thickness ratio, etc. Our trait principal component analysis (PCA) results lacked the clear clustering of plants from different succession communities. Changes of trait syndromes facilitated plants to coexist in one or more communities along successional subtropical forest. Thus, complex species compositions within different succession communities were shaped as the result of reducing the overlap of resource requirements and the competitive intensity of co-existing plants.