Long-term landscape structure change in contrasting land occupation strategies of the Brazilian Amazon

Abstract

Land occupation policies can have unintended consequences to the landscape structure, with pervasive effects on biodiversity. Here we investigate the long-term consequences of contrasting historical types of occupation in Amazonian landscapes (few large vs several small landowners) on forest fragmentation and landscape structure. Using satellite Landsat images series, we identified typologies of deforestation in the Amazon connected to large landowners (i.e., Geometric pattern of deforestation) and small landowners (i.e., Fishbone pattern). Within those images, we selected seven landscapes (50×50 km) of each deforestation pattern and tracked the evolution of landscape spatial configuration through landscape metrics (forest fragments number, size, shape, and edge-core relation) from 1985 to 2015. Results showed that the amount of deforestation area was similar across time, irrespective of the deforestation patterns. However, in association with the Fishbone pattern, forest fragmentation resulted in numerous small forest fragments, with more intricate shape and forest patches containing two to three times more forest under edge effects when compared to the Geometric pattern. On the other hand, landscapes with Geometric patterns had larger deforestation patches, exposing the forest and the biodiversity to a less permeable or a low-quality matrix (usually pasture or soybean) and its known negative consequences. As a result, the threats to biodiversity should be different in each kind of landscape, despite both having the same levels of deforestation. The long-term consequences to the landscape structure will remain an untracked problem for forest conservation unless reforestation policies, tailored to the specificities of each typology of deforestation and forest remanent, are considered for the region.