A phytosociological study was developed in flooded area of the Mata dos Godoy State Park, municipality of Londrina, southern Brazil (23º27'S and 51°15'W) in order to determine the diversity and the structure of tree species. Fifty 10m×10m plots (0,5ha) were used to sample trees with GBH (girth at breast height) > 15,0cm. Density, frequency and dominance parameters were calculated for each species. In this area 912 living and 58 dead individuals were sampled. The living individuals were distributed in 26 families, 49 genera and 64 species. The value of the Shannon's diversity index was 3,44. The families with the highest species number were Leguminosae and Myrtaceae, while Nectandra megapotamica (Spreng.) Mez, Chrysophyllum gonocarpum (Mart. & Eichler), Actinostemon concolor (Spreng.) Müll. Arg., Ruprechtia laxiflora Meisn. and Trichilia catigua A. Juss. were the most important species in this area. The less diversity and structure of this area is related to flooding and the species adapted to this environment are recruited in higher abundance.
flooded area; phytosociology; size classes; southern Brazil; species richness
