Fitossociologia e distribui？？o de espécies arbóreas em uma floresta ribeirinha secundária no mnicípio de Rio Claro, SP, Brasil

(phytosociology and tree species distribution in a secondary riverine forest in the municipality of rio claro, sp, brazil). the floristic and phytosociological structure of a secondary riverine forest situated on a micro-basin area of the ribeir？o claro river (rio claro, sp), was characterized in order to investigate the structure and species distribution in a community with high canopy cover and soil water regime heterogeneity. all tree individuals with perimeter at breast high (pap) 3 10 cm were sampled in 44 plots of 10 × 10 m. the water regime was evaluated for a year and the canopy cover was measured with spherical densiometer. phytosociological descriptors were calculated for the entire sample area and for each group resulted from the ordination and clustering analysis (dca and cluster). low floristic richness (22 species) were found and high importance values were concentrated in a few species. in a local scale, the area presented three distinct micro-environments in relation to the composition and structure of the tree community. the most abundant species distribution was associated to spatial light variation within the forest, due to canopy openness (gaps), and soil water regimes, characterized by different drainage and flooding conditions in the plots during the year.