Floristic composition and biogeographic relations of a subtropical assemblage of climbing plants

Abstract

Most of southern Brazil is located in a subtropical region, thus representing a climatic and biogeographic transition, which results in different floristic contingents of both tropical and temperate origin in any particular study area. In order to verify the biogeographic affinities of climbing plants, a floristic survey was carried out in a Semideciduous Seasonal Forest remnant located in mideastern Rio Grande do Sul. The presence of the sampled species was recorded for three gradually more distant areas along four divergent expansion lines starting from the study area: northeast, northwest, midwest, and southwest. The distribution data were compiled from the available local and regional literature. The 82 species found comprised 55 genera and 33 families; most species occurred in a single family (Asteraceae), followed secondarily by Apocynaceae, Passifloraceae, Bignoniaceae and Fabaceae. Many species presented a relatively large geographic range, and most species occurred along the northern tropical expansion line. Multivariate analysis included the study area in a group formed exclusively by rain forests of a northeastern expansion line, indicating a southern continuity of the Brazilian Atlantic Forest, although it was locally represented by a lower number of species.