Functional turnover and community assemblage during tropical forest succession

Changes in species composition during the succession of ecological communities potentially reflect the differential effects of environmental filters and limiting similarity on structuring communities. As ecological succession can represent community assembly in action, understanding how successional time affects the functional and phylogenetic structure of communities can reveal the influence of different factors on the assembly process. We analysed functional patterns of multiple traits related to the succession of tropical forests to answer if there are trait convergence and/or divergence with regeneration age, and if functional and phylogenetic diversity can be predicted by forest age. We compiled checklists from studies of 23 successional forests in Brazilian Atlantic Forest, ranging from 4 to 120 years old. We also compiled functional traits for a total of 355 species. We analysed the data by a method that includes scaling-up trait-based data to the community level and matrix correlations of multiple traits. We built linear models to show the relationship between each trait and diversity (taxonomic, functional and phylogenetic) with successional time. We found no phylogenetic signal at the species pool and metacommunity levels, but significant trait divergence (tree guild, leaf slenderness, leaf area, pollination entomophilous generalist and pollination by vertebrate) and trait convergence (arboreal habitus, tree guild, leaf compoundness, pollination entomophilous generalist) patterns related to the successional gradient. Also, functional diversity increased during succession, with a significant increase in leaf slenderness and zoochoric dispersal and decrease in tree guild. Phylogenetic diversity also increased along the successional gradient. We found that the communities in the studied successional gradient are structured by both environmental (measured by trait convergence) and biotic (measured by trait divergence) filtering. The species turnover and diversification at taxonomic level are followed by well-defined patterns of trait turnover, revealing that community assembly is constrained by environmental filters at the beginning and by limiting similarity at the advanced stages of the succession