Chronic anthropogenic disturbance on Caatinga dry forest fragments

Understanding how chronic anthropogenic disturbances are distributed in space leads to more effective conservation and management practices. This study provides a large-scale overview of how the Caatinga dry forest is potentially altered by chronic anthropogenic disturbance. In particular, we investigate how the intensity of the potential disturbance varies (a) among geographic regions, (b) among fragment sizes, and (c) as a function of distance to the fragment edge. A chronic anthropogenic disturbance index (CDI) was derived to represent five anthropogenic disturbance vectors: human population, infrastructure, grazing, logging and fire. CDI was spatialized for the whole Caatinga landscape (826,411 km(2)) and posteriorly averaged forc. 47,100 remaining fragments. Chronic anthropogenic disturbance was unevenly distributed across the Caatinga landscape, with more conserved sites on the western and southern regions. Larger fragments were, on average, as disturbed as smaller ones. However, smaller fragments varied from highly disturbed to very well preserved depending on the regional context. Strong edge effects were recognized for the CDI and its five vectors. Policy implications. Although half of the original Caatinga vegetation remains, most remaining fragments probably suffer with chronic anthropogenic disturbances. This suggests that a large portion of the Caatinga can be currently threatened, and its biodiversity and natural resources eroded by processes that are less evident than habitat loss. Proper management practices and expansion of the existing protected area network are needed to halt the Caatinga biodiversity decline. Conservation and management actions in tropical ecosystems seem to be more urgent than previously assumed.