Diversity and Structure of the Arbor Component in Ravine and Flat Land Environmental Conditions: A Case Study in Tropical Rainforest, Brazil

The objective of this research was to study the diversity and forest structure in fragments with different topographic conditions, relating these components to the tree biomass compartment. Two small fragments of post-disturbance Atlantic Forest, on ravine and flat land areas, were sampled. The numbers effective Hill diversity (qD) and the intensity curves was obtained in both environmental conditions and compared by rarefaction (P = .05). The forest structure was dimensioned using the basal area (BA); diameter of breast height (DBH), total height (H) and tree biomass above ground (AGB), estimated using an adjusted local equation for endangered forests. According to the diversity profiles, it was proved that the ravine has a higher qD for all orders, for both dominant and uncommon species (P < .05). Regarding the forest structure, the ravine showed higher H (greater competitive tendency), a lower investment in DBH (x̅ = 13.05 ± 7.94 cm) in relation to the flat land (x̅ = 38.01 cm ± 17.28 cm), and consequently, low investment in AGB ( x̅ = 306.20 ± 354.08 kg e x̅ = 2336.37 ± 2078.34 kg ravine and flat land, respectively). The present study confirmed the hypotheses of structural change and diversity of the tree component in the different conditions studied, being these factors considered important for the processes of community structuring. These evidences trace back the importance of small forest fragments in ravine conditions and their role in maintaining the Atlantic Forest biodiversity.