Pedological and topographical influence on the distribution of tree species in different stages of regeneration

Abstract

The aims of this study were to analyze the pedological and topographic variables of two forest fragments in different stages of regeneration and verify the relationship with the physiognomic and community structure of the vegetation. The study was developed in the Edge of the Plateau of Rio Grande do Sul state (RS), Brazil. Ten plots of 10 x 20 m (0.46 ha) were established in a secondary forest fragment (FS) and 9 plots (0.18 ha) in the capoeira fragment (CA), using a systematic sampling method. It was used vegetation survey and measured pedological and topographic variables. The variables were selected by Principal Component Analysis (ACP), separated into groups by cluster analysis (AA) and compared to phytosociological variables through canonical correspondence analysis (ACC). The greatest species richness was identified in soils with higher nutritional quality, where the variables with the greatest influence on the distribution of the species were: depth, sand, pH and red (IV) index. On the contrary, in CA, the greatest species richness was associated to the more acidic and nutrient poor soils in which the silt, altitude and IV variables showed greater influence on the species distribution. These results highlight the importance of pioneer species in this stage of forest regeneration.