Community assembly during recovery of tropical lowland rain forest from abandoned shift-ing cultivation lands on Hainan Island, China

Abstract

Aims A major challenge in studies of tropical forest successional dynamics is to reveal the relative importance of deterministic versus stochastic processes affecting species composition, spatial distributions and their rates of change. Here, we tested succession trajectory of tropical secondary forests follow equilibrium or non-equilibrium dynamics by evaluating community reassembly for tropical lowland rainforest recovery on the abandoned shifting cultivation lands on Hainan Island of south China. Methods We explored species composition and dominance of different size classes (seedlings, saplings and adult trees) of communities along a chronosequence of secondary forest plots ranging from 15 to 60 years since abandonment after shifting cultivation. We included two old-growth forest plots for comparison. Important findings Both species diversity for the three size classes and the species similarity index among size classes in old-growth forests were significantly higher than in secondary forests. However, the proportion of dominant species in old-growth community was lower than that of secondary forests. Species similarity between secondary forests and old-growth forests increased with forest recovery, supporting the view of equilibrium succession dynamics. In each recovery stage, the number of individuals, species richness and abundance-based coverage estimator of seedlings were lower than those of both saplings and adult trees. Moreover, the species composition of seedlings in secondary forests differed significantly from that of both saplings and adult trees, suggesting that seedling recruitment might be an unpredictable process. Our results highlighted that the community assembly processes during secondary forest recovery are driven simultaneously by stochastic and deterministic processes.