Mature Atlantic Forest from São Paulo metropolitan area: diversity, arboreal composition, and floristic variation along a littoral-interior gradient, São Paulo State, Brazil

ABSTRACT

This survey was carried out in order to characterize the tree component of mature Atlantic Forests from São Paulo metropolitan area, São Paulo State, Brazil, to check if there is a floristic variation along the highlands of the region towards littoral-interior, to verify which environmental factors could have influence on it, and to contribute to the classification and conservation of these forests. In order to perform this study, two plots (20 × 50 m) were installed on three mature forests located in the cities of São Paulo (Marsilac), Cotia (Morro Grande Forest Reserve), and Itapevi, with samples from all arboreal individuals with circumference at breast height CBH ≥ 15 cm. Clusters (UPGMA) and ordinations (DCA) analysis were performed between the plots, using species density data. This survey resulted in a sample of 943 trees belonging to 50 families, 109 genera, 184 species; Shannon index 4.62; Pielou equability 0.88; basal area 46.1 m² ha^-1, and density of 1.572 ind ha^-1. The clusters and ordination analysis indicated that there was greater similarity between Marsilac and Morro Grande, with a tendency to form a more homogeneous floristic block, while Itapevi was isolated from the others. This floristic variation was attributed to the drier winter in Itapevi region, allowing the occurrence of some species usually associated with seasonal semideciduous forests. However, it was verified that the forests of São Paulo metropolitan area are composed of a predominantly ombrophilous flora, with variable presence of semideciduous forest species, mixed, or cold-wet forests. The high diversity of the mature forests, the presence of a large number of rare and threatened species, and the scarcity of these forest remnants, require immediate protection and conservation actions.

Keywords:
Atlantic forest; biodiversity; climax; conservation; phytogeography