Plant trait distribution and the spatial reorganization of tree assemblages in a fragmented tropical forest landscape

摘要

Tropical forests have been rapidly converted into human-modified landscapes but the effects of such conversion on community spatial organization have been rarely addressed. In this paper, we examine to what extent the spatial reconfiguration of tropical landscapes alters plant trait distributions and the spatial organization of tree assemblages. A set of 117 tree species and 1422 individuals (a parts per thousand yen10 cm DBH) inhabiting a fragmented Atlantic forest landscape in Brazil were assigned into categories of both vegetative and reproductive life-history traits, and matrices of trait frequencies were correlated to four spatial patch metrics via the concepts of trait-convergent, trait-divergent assembly pattern, and measures of functional richness, evenness, and diversity. Life form and seed dispersal syndrome exhibited the highest and significant degrees of trait-convergence related to connectivity and patch size gradients, respectively. Trait divergence based on seed dispersal syndrome and regeneration strategy emerged as well, particularly in response to patch area and connectivity. Finally, some functional diversity (multiple-traits) measures correlated with either a particular patch metric or species richness. Our results suggest that the spatial distribution of life-history traits and strategies exhibited by tree species correlate with spatial patch metrics, supporting the notion that human disturbances result in new environmental gradients able to spatially reorganize and restructure tree assemblages at broad spatial scales into human-modified landscapes.