This study aimed to find and compare the floristic composition and structure of two floodplain forests areas located in the extractive reserve Chocoaré - Mato Grosso, Santarém Novo, PA. The floristic inventory covered 1.5 ha in plots of 10 x 100 m, distributed in the area 1 (1.0 ha) and area 2 (0.5 ha). The individual trees with circumference at 1.3 m height from the soil were identified (CBH > 30 cm) and demonstrated the richness, basal area, and the Importance Value Index (IVI) in each area. The relationship among the areas was carried out by the species similarity, density, basal area, cluster analysis, and indicator species. In the area 1, there were 613 ind.ha-1 (26.67 m2.ha-1), distributed in 17 families, 33 genera, and 34 species with Euterpe oleracea, Enterolobium maximum, Symphonia globulifera, Pterocarpus amazonicus, and Virola surinamensis with the highest IVIs. In the area 2, with 744 ind.ha-1 (35.34 m2.ha-1) in 13 families, 24 genera, and 26 species with Mauritia flexuosa, Euterpe oleracea, Virola surinamensis, and Tapirira guianensis and Inga thibaudiana with the highest IVIs. The areas recorded low similarities among themselves (0.18), and both the density and basal area were higher in the area 2. The grouping separated the areas among them. Only 15 were indicators from 51 species. It is concluded that the forests had low richness with little resemblance among the tree populations. The indicator species occurred in the areas 1 and 2.
Phytosociology; Extractive reserve; Santarém Novo
