The loss of natural forests due to the anthropic pressure carried the secondary forests to occupy great proportions of areas in East of Amazon. With the aim to known the characteristics of a arboreal community and the population structure of the most representative species, it were investigated species richness, structure, and floristic composition of a 40 years old secondary forest in the municipality of Bragança (01°11'S and 46°40'W), Pará State, Brazil. It was sampled all individuals of arboreal species (except Arecaceae) with DBH > 5 cm in 150 plots of 10×10 m. It was registered 2,934 individuals in 154 species, 101 genera and 40 families. The density was 1,956.00 ± 643.45 ind. ha-1 and the basal area of 17.358 ± 7.952 m² ha-1 with a Shannon diversity index of 4,030 nats. ind.-1. The species with the highest abundance of individuals were Myrcia bracteata, Casearia arborea, and Maprounea guianensis. The species with the highest basal area were Tapirira guianensis, Croton matourensis, and Maprounea guianensis. The richness of species fitted to the lognormal distribution model just for basal area and not for number of individuals. In 40 years of succession, this forest shows high species diversity and low basal area.
Floristic composition; community ecology; lognormal distribution; secondary succession; diversity indexes
