The effect of the surrounding matrix on bird communities in fragments of the Brazilian Atlantic Forest

Abstract

Despite being one of the most diverse biomes in the world, the Atlantic Forest is currently restricted to small isolated fragments and, therefore, the majority of its fauna is declining or threatened. This is mainly due to habitat loss, edge effects, and other patch-level negative effects. Here we study whether the type of matrix surrounding Atlantic forest fragments affects patterns of bird diversity. We hypothesize that fragments in contact with a matrix dominated by Eucalyptus plantations would have more diverse bird communities compared to matrices dominated by pastures. We assessed the richness, abundance, and functional diversity of birds at the edge and in the interior of fragments of Atlantic Forest surrounded by pastures and by plantations of Eucalyptus trees. Even though all the studied fragments showed relatively low values of species richness, those surrounded by the Eucalyptus matrix had higher species richness and evenness at the edge of the fragments compared to those surrounded by pasture. Furthermore, the bird community in contact with the Eucalyptus matrix had higher functional diversity and higher abundance of bird groups generally sensitive to disturbances. Our data illustrate the importance of the matrix composition surrounding fragments. While replacing Atlantic forests with Eucalyptus plantations will lead to a reduction in bird diversity, our data suggest that nevertheless Eucalyptus plantations can buffer edge effects for forest birds compared to more abrupt transitions, such as with pastures.