Source-sink potential of the Atlantic forest Central Corridor

Background. The Brazilian Atlantic Forest is one of the most diverse and threatened biomes in the world. The fragmentation and deforestation have strong impacts upon biodiversity, and many ecological theories have been brought in discussion in order to predict its consequences. Many approaches, such as Pleistocene Refuges Hypothesis, Metapopulation and Source-Sink Theories, Island Biogeography Theory, Stepping-stones and SLOSS debate have been extremely useful in this issue, but not in practice as much as in theory. In this scenario, the aim of this study is to present simple tools to apply those theories in practical measurements, classification and knowledge about the role of conservations unities and small fragments in the landscape of the Central Corridor of Atlantic Forest. Methods. 33 forest fragments were selected over the Atlantic Forest Central Corridor territory to sample different sizes, altitudes and legal protection categories. Physical attributes and measures were taken using GIS data (as area, shape and connectivity). Results. There is a vast variety of connectivity among fragments in the Central Corridor landscape. Most of the federal conservation units act as a source or semi-source patch in the metapopulation in their own matrix, while most of the private areas act as sink patches. However, some source patches are too isolated to participate in the metapopulation system, acting as an isolated refuge. In addition, both source and sink fragments suffer strong edge effect, and some of them are not suitable for sustain species adapted to core area. Discussion. Edge effect is a real threat over any fragment, mostly because of the small area or the irregular shape. Efforts must be directed to minimize this impact. Small private patches are not capable to sustain many endangered and endemic species and are not suitable for releasement of rescued wildlife, but they are very important for the metapopulation and source-sink system, relieving the competition effects inside source patches, and acting as stepping-stones. Governmental incentives to preservation of every small natural area may act as a vital component of greater conservational strategies. Maintenance of large federal conservation units alone is not enough to decrease the danger of extinctions. Some of these conservation units are isolated fragments that may represent the only remain of the Pleistocene refuges, and they need small fragments around to keep the biologic flow of the metapopulation dynamics.