Influence of geographical distance in richness and composition of tree species in a tropical rain forest in eastern Amazonia

Two theories in ecology explain species distribution in tropical forests: the Neutral Theory and Niche Theory. The first predicts the species distribution is related to processes such as dispersion, and the second predicts that species distribution is related to competitive interactions between species. Studies have shown that the species similarity in a plant community decreases according to the geographical distance in the tropics. The aim of this study was to assess the influence of the distance on tree species richness and composition within and among six plateaus in a tropical rain forest at the Sacará-Taquera National Forest, Pará, Brazil. These plateaus are exploited for the bauxite extraction where the forest cover is completely removed. In this study, the number of plots used in each plateau ranged from 18 to 22. There was a negative correlation of the species similarity to the distance, whithin and among the plateaus. There was no correlation of species richness to distance (whithin and among the plateaus), except for the plateau Aramã. The results of this study support the Neutral Theory and have important implications for the conservation as well.