Estrutura e composição florística do estrato arbóreo em duas zonas altitudinais na mata atlântica de encosta da Região do Imbé, RJ

Abstract

The Imbé is one of the main Atlantic forest remnants in the Rio de Janeiro State. The aim of this study was to test whether differences in forest structure and floristic composition exist between two tree communities at different altitudes (site 1 at 50m high and site 2 at 250m high). Five plots of 30m×40m (1200m2) were setup in each site. All trees with DBH ≥ 10cm were tagged and measured. A total of 210 species was sampled, distributed in 158 genus and 43 families. Both sites is showed similar values for basal area, number of individuals and canopy height. The species diversity (H’= 4,21 and 4,30, respectively to site 1 and site 2) can be considered to be within the highest values found for Atlantic forests. Among the families, the Euphorbiaceae had the highest values of CV in both altitudinal sites. The family with the highest richness of species was the Leguminosae (26 species). Only 57 species were common to both forest sites. At site 1, the species with the highest CV were Hyeronima alchorneoides Allemão (14,3), Actimostemon verticilatus (11,4) and Rustia formosa (Cham. & Schltal.) Klotzch (10,7), while for the forest at site 2 they were Actimostemon verticilatus (Kl.) Baill. (13,8), Euterpe edulis Mart. (12,4) and Mabea fistulifera Mart. (8,1). The results showed that the floristic composition changed with altitude, but not the forest structure and species diversity.