Estrutura e organização de comunidades de aves em áreas de Mata Atlântica primitiva e explorada por corte seletivo

Abstract

The purpose of this study was to evaluate the effects of selective logging on a bird community in the Brazilian Atlantic forest. Two areas were selected for avian surveys, both qualitative (presence-absence) and quantitative (censuses): a non-fragmented primary forest (designated M1) and, very near to it (500 m), a selectively logged forest (designated M2). These surveys were designed to answer how selective logging affected the richness and the composition of the bird community and the abundance of the species present. During 25 months, the abundance of species with similar ecological requirements (within the same guilds) were compared and tested between M 1 and M2, to determine which ecological groups were affected. The structure of the vegetation of the sites was also measured, in arder to evaluateits influence on the composition and structure of these bird communities. Though most parameters of the vegetation structure were reduced in M2, patterns of richness and diversity of the bird communities varied little between M1 and M2. The guilds, also showed few changes between the communities studied, but in most guilds at least one member was adversely affected by the selective logging. Even though the indices of richness and diversity were not significantly different between the bird communities of M 1 and M2, important variation was seen in their composition. Dynamic processes such as colonízation and extinction might explain the marked differences detected in the composition of the bird communities, and the abundances of the bird species between the sites. The process of species colonization, detected in M2, led to the replacement of species in the guilds that lost species there due to extinction. Understory and terrestrial insectivores were the most sensitive ecological groups (with most species extinct in M2), as also observed in the process of forest fragmentation in other parts of the Neotropics. Logged and secondary forests in the Atlantic forest can harbor rich and diversified bird communities, but multivariate analysis showed that these communities differ appreciably in structure from those in virgin forest. The following procedures should be adopted to minimize adverse effects of selective logging on bird communities in the Atlantic forest:(1) Logged areas should be elose enough to unfragmented, unlogged forests to allow recolonization of some species. (2) The exploitation of the forest should be carried out using as few roads as possible, limiting the use of mechanized equipment to fell and transport the trees to that strictly necessary. (3) Areas designed for logging should be explored with long-term rotation to allow enough time for regeneration of the forest