Efeito da palmeira Acrocomia intumescens Drude (Arecaceae) sobre a biodiversidade de formigas em um fragmento de Mata Atlântica do Nordeste do Brasil.

Abstract

With this study we propose to investigate the effect of the Acrocomia intumescens palm on the structure of ant communities in an Atlantic Forest fragment of Northeastern Brazil. Investigating the factors that assemble and organize biological communities is one of the most studied topics in ecology. At the same time as advancing changes in ecosystems, it is essential to assess the integrity of communities. It is known that several arboreal palms affect the structure of plant communities, and the ants for being closely related to these can be affected by a cascade effect. To investigate the effect of the Acrocomia intumescens Drude palm tree on the structure of ant communities, we selected 10 palm trees (at least 100m apart), we measured the area of each palm tree's gaps (based on the ellipse area), we traced a 10m radius around each palm considered an experimental unit and we count the number of palm trees within that radius. We selected an equal number of experimental units in the forest understory at a minimum distance of 20m from any palm tree. We added a set of fall traps (pitffal), both in the gaps and in the understory. We categorize taxonomic diversity based on Hill's numbers (0D - Rare species, 1D - Common species and 2D- Dominant species). We characterized functional diversity based on five functional attributes and calculated Functional richness (FRic), Functional Equability (FEve) and Rao’s Quadratic Entropy (RaoQ). We manage a series of statistical models, first to understand the effect of habitat (gaps versus understory), and second to understand the effect of the size of the gaps area and the number of palm trees on taxonomic and functional diversity. Our results indicate that palm trees and understory have equivalent numbers of rare, common and dominant species, as well as, the richness and functional divergence is maintained between habitats. However, functional equability is greater in gaps than in forest understory. We also found a pattern of species substitution between habitats, but the functional composition did not vary between gaps and understory, which indicates the presence of ecologically equivalent species in the habitats. In summary, palm trees change the structure of ant communities and partially reduce diversity.