Conversion of the Atlantic Forest into native and exotic tree plantations: Effects on bird communities from the local and regional perspectives

In the current scenario of a fragmented Atlantic Forest, with less than 7% of the original cover remaining, the dominant agricultural and agroforestal matrices should be incorporated into conservation planning. However, little information is available on the conservation value of different land uses, especially those of commercial tree plantations. We studied bird communities in native forests and in commercial plantations of an exotic (Pinus spp.) and a native (Araucaria angustifolia) tree species, through local and regional surveys in the Upper Paraná Atlantic Forest, Argentina. Bird species richness was 50% lower in plantations than in native forests, showing the negative impact of replacing the natural forest with tree plantations. Both species richness and composition were similar between Pine and Araucaria plantations (independently of the extent of the surveyed area); yet, there is a threatened species only found in Araucaria forests. Estimated bird richness in native forests was higher in the regional than in the local survey, likely reflecting habitat heterogeneity. Forest-dependent and threatened species were especially affected by the replacement of native forest; bird communities in commercial plantations were mainly composed of forest-generalist and edge species rather than forest-dependent species. Our study demonstrates that major changes in bird species richness and composition are associated with forest replacement by commercial tree plantations under the current management conditions. Many silvicultural measures could favor bird communities, such as the protection of forest remnants inside plantations and the improvement of forest belts between stands.