Aves e efeitos da fragmentação em um remanescente florestal do Quadrilátero Ferrífero, MG

Abstract

The Iron Quadrangle (IQ) is the global leader region in the production of metallic minerals, mainly iron mineral. This intense mine activity is responsible for the transfiguration of the landscape causing impacts that have not yet been deeply investigated on the regional biodiversity. The first chapter presents a list of birds of a protected forest remnant of the region, a private nature reserve named Mata Samuel de Paula (MSP). This nature reserve is 147 ha wide and is located in the transition area between the Atlantic Forrest and the Cerrado, near the city of Nova Lima. The vegetation is composed by seasonal semideciduous forest, savanic phytophysiognomies and ferruginous fields. The survey was made by audiovisual observation and mist-net captures throughout a year. It has been registered 159 species of birds, from which it has been assessed their habitat and frequency of occurrence, seasonality and migratory situation, endemism and conservation. The richness was estimated in 188 ± 7 species. The list presents a globally nearly-threatened with extinction species, the Embernagra longicauda, one species globally endangered, Scytalopus indigoticus, one species considered vulnerable in Minas Gerais state and in the world, Poospiza cinerea, and another considered endangered in Minas Gerais, Campephilus robustus. It also includes 29 endemic species of Atlantic Forrest, three of Cerrado and one of mountain tops of the southeastern Brazil. It has as well been elaborated a comparative analysis of avifauna of other five protected areas of IQ which has also shown other 44 endemic species of the Atlantic Forrest, five of the Cerrado and one of mountain tops of the southeastern Brazil, apart from other 17 species threatened with extinction. The second chapter examines the effects of fragmentation on the avifauna of the MSP. The hypothesis of the ‘random sample’ states that the small fragment communities are random samples of the original areas once they are formed by stochastic extinctions. An alternative approach understands that the probabilities of extinction are related to biological attributes of the species, generating nonrandom communities in small fragments. It is tested whether biological attributes such as guilds, flexibility in the use of the habitat, rarity and endemism are related to the absence of species in fragment. The analyses were made by the comparison between the observed community and a hypothetic community generated from a random extinction regime on the community of a big relatively well-conserved fragment in the region. Some guilds are more weakenedand other less, being ‘internal-bark insetivorous’, ‘terrestrial insectivorous’ and ‘large arboreal frugivorous/insectivorous’ the more sensitive and ‘small understory arboreal frugivorous/insectivorous’ and ‘nectarivorous/insectivorous the more resilient. It is also concluded that the rare and uncommon species are more absent then expected, as well as the species with low tolerance to edge and secondary forests. This result indicates that the absence of species in the MSP does not happen randomly, it is indeed related to intrinsiccharacteristics of the species. Based on the results it has been inferred the factors of landscape which allied to the characteristics of the species determinate the most the sensitivity to fragmentation, being the small size and the isolation of the fragments the most important. Nature reserves of great area or those having the suitable connectivity and the control on the wood extraction and hunting are to be considered fundamental to the conservation according to the results.