Variação da composição floristica e da diversidade alfa das florestas atlanticas no estado de São Paulo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

One important question in the ecology of tropical forests concerns the predictability of their floristic composition and species diversity. This theme is assessed in this study by comparing atlantic forests in São Paulo state, for which there is considerable information about tree taxa distribution and abundance. The study pursues the idea that environmental factors influence the organization of these forests and that different species respond differently to these factors. To investigate this idea, this study was structured in three chapters, which investigate the occurrence of floristic and diversity patterns and explore the relation between these factors and the main geographic and climatic variations in the state of São Paulo. The first chapter compared forest surveys by considering the relative abundance of the species to provide a current picture on the existing variations and to get ecologically significant vegetation groups characterized by indicator species. The second chapter investigated the floristic variation at the family level, aiming to analyze the response of tree taxa to environmental gradients, as well as to compare the results with other tropical forests. Finally, the third chapter analyzed the variation of the alpha diversity of Paulian forests, with the objective of achieving geographic and climatic models. Results of this study indicated the occurrence of a unique main gradient for floristic and diversity variation, which included the ombrophilous and semideciduous forests, and was mainly related with distance from the ocean and duration of the dry period. This gradient was weakly associated with forests on beach ridge and deciduous and swamp forests, which occur in more stressful environments, thus suggesting the more specialized nature of these formations in relation to ombrophilous and semideciduous forests. However, although part of the main gradient, the semideciduous forests have tree flora and community structure more homogeneous than ombrophilous forests. Besides having a larger regional species pool, ombrophilous forests also have higher local average alpha diversity, or richness, in relation to the other forest types. Great part of this high richness can be attributed to the predominance of some understory families, such as Myrtaceae, Rubiaceae, Melastomataceae and Sapotaceae, which dominate locally

ASSUNTO(S)

florestas - são paulo (estado) floristica - são paulo (estado) floristics diversity forests diversidade

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