The shrinkage of a forest: Landscape-scale deforestation leading to overall changes in local forest structure

Habitat loss is one of the primary drivers of change in forest biodiversity and ecosystem function worldwide. The synergetic effects of habitat loss and fragmentation might lead to profound impacts on forest structure and composition, conducting forest fragments towards early successional stages (retrogressive succession). In this study, we tested this hypothesis by evaluating how landscape-scale forest loss affects the forest structure. We sampled forest structure descriptors in 40 forest sites in landscapes ranging from 3 to 100% forest cover. Forest cover was negatively related to most of the structural variables, generally in a non-linear manner. In contrast, dead trees and logging were ubiquitous and not related to forest cover. The forest remnants in more deforested landscapes retain early successional forest attributes, with tree assemblages that are less dense, shorter, thinner, with an overall basal area loss, and with increasing canopy openness. This structural degradation indicates that landscape-scale forest loss strongly determines the trajectory of the local forest structure, pushing forests to a retrogressive succession process, which is more likely to occur in deforested landscapes and can lead to functional forest erosion. Our findings indicate that remnants within deforested landscapes may suffer recruitment limitation, primarily of large trees. Additionally, the forest structure characteristics were more severely degraded in landscapes with less than 40% forest cover. In the face of these results, the recommendation is to avoid the reduction of forest cover below this threshold, at which point structural erosion becomes more severe, with predictable negative consequences on biodiversity and ecosystem service maintenance. (C) 016 Elsevier Ltd. All rights reserved.