The purpose of this study was to attempt to detect a floristic transition in forest along an altitudinal gradient on a mountain side in southern Bahia, Brazil. The study site is located at the east-west transition from tropical moist to semideciduous forests. A belt transect of one hectare (10 × 1000 m) was established running up the slope (from ca. 350 m to 750 m elevation). All included trees and lianas > 5 cm in diameter at breast height were numbered, collected, and measured. Density, dominance, frequency, and importance values (IV) were calculated for each species. We encountered 1400 individuals and 264 species of woody plants in 56 families. Cariniana legalis (Mart.) Kuntze had the highest IV, based on the dominance of a small number of trees. Discocarpus pedicellatus Fiaschi & Cordeiro and Ampelocera glabra Kuhlm. were the most frequent trees, with 90 and 86 individuals respectively. Ninety-six species were represented by a single individual. The Fabaceae and Myrtaceae were the most diverse families with 37 and 31 species respectively. Cluster analysis and correspondence analysis (DCA) revealed that the composition of the forest along the uppermost 30 percent of the transect was distinct from the rest. The lower and upper forests can be considered respectively as semideciduous and moist forests. Although there are some well-marked floristic differences between these forests, both clearly belong to the southern Bahian sector of the Atlantic coastal forests.
altitudinal gradient; Atlantic coastal forest; Bahia; tropical semi-deciduous forest
