This study aimed to evaluate tree floristic composition of the submontane Atlantic Forest in the Imbaú region, Silva Jardim, Rio de Janeiro. About 50 years ago, the forest fragmentation process was begun in this region due to farming practices. Five forest remnants were selected and four plots (100×5 m) were systematically located in each one. All trees with dbh > 5 cm were sampled and identified. In the one-hectare sample area, 161 species in 39 families were sampled. Species similarity was high between fragments (Morisita index ranging from 0.36 to 0.79). The families Leguminosae, Lauraceae and Rubiaceae showed the highest values of species richness. The studied area had a high density of early secondary species and a decrease in canopy species richness when compared to a mature forest nearby. These results indicated characteristics of secondary forests. When compared to 17 forests of Rio de Janeiro State, the Imbaú region showed stronger floristic relationships with submontane forests, especially those geographically closer. Due to its ecological importance for the local flora and fauna, plus the advanced stage of fragmentation in the region, the Imbaú region should be considered as a priority area for adopting conservation and management practices.
floristic richness; Atlantic Forest; forest fragmentation; conservation; Rio de Janeiro