Abstract

This study aimed to analyze the interactions between environmental variables and the occurrence of tree species in the understory of an Atlantic forest fragment in Southeastern Brazil. The vegetation data collection was carried out in ten locations, with trees having diameter at breast height (DBH) larger than 5 cm and with distinct physiographic characteristics, orientation and slope. The following variables were collected at each site: sum of the soil bases, soil moisture, leaf area index (LAI) and canopy transmissivity of photosynthetically active radiation (PAR). The interaction between environmental variables and vegetation was investigated employing the canonical correspondence analysis (CCA), using data from the natural regeneration (TNR) of forty-six species and the environmental variables of the locations studied. The Monte Carlo test showed that the correlation between TNR values for the species and environmental variables was statistically significant. The occurrence of four primary species groups was identified through this analysis. Considering the availability of solar radiation, one species group was observed to have occurred under the open canopy with high transmissivity of PAR, and another in locations with high LAI values and low PAR transmissivity. When soil variables were considered, we were able to distinguish two groups; a group of species showed preference for sites with fertile soil and high water content and another group that was more predominant in sites with drier soil, usually on steeper slopes.

Key words: Brazilian Atlantic forest, environmental heterogeneity, photosynthetically active radiation, leaf area index.