Sucessão ecológica da vegetação arbórea em florestas secundárias do nordeste do Estado do Pará

Abstract

This work carried out an ecological characterization of a secondary tropical forest frgment inseted in a "Reserva Particular do Patrimônio Natural"(RPPN) in Northeast of Para State - Brazil, where they had been identified and measured all plants with DBH ³ 5cm in 16 plots of 10m x 50m and identified and counted the individuals with DAP < 5cm, in 16 subplots of 2m x 2m. Was verified that the vegetation is ecologically characterized in a mature sucessional fase, presenting a continuous and decreasing diameter distribution (j-reverse), being characterized for the species Pourouma guianensis, Tapirira guianensis, Inga heterophylla, Eschweilera coriacea, Xylopia nitida, Byrsonima duckeana, Cupania scrobiculata, Ocotea guianensis, Symphonia globulifera and Guatteria poeppigiana. In comparison with other secondary forests one suggests that the history of occupation of the land and the degree of isolation of fragment have significant impacts on the diversity of plant communities.

This study describes a floristic gradient of secondary forest chronosequence in northeast of Para State - Brazil, from 19 sites of different ages, evaluated in different years. Data of density were used and carried out regression analysis for richness, diversity, density, maximum relative density and equitability in relation to the age. The hierarchic grouping method of analysis was used, being the Euclidean distance used as measured of dissimilarity and applied an Principal Component Analysis (PCA) for confirmation of the groups. After the definition of the groups, was made an indicating analysis of species (IndVal) on the same matrix used for the grouping analysis. A geographic gradient in the analyzed chronosequence was found and the species Tapirira guianensis, Vismia guianensis, Inga alba, Lacistema aggregatum, Croton maturensis, Abarema jupunba, Inga rubiginosa, Guateria poepigiana and Thyrsodium paraense are indicators of Para(Brazil) northeast secondary forests analyzed in this study.