Impacts of Protected Area Deforestation on Dry-season Regional Climate in the Brazilian Amazon

Abstract:

Rainforest in protected areas in the Brazilian Amazon is at risk due to increasing economic pressures and recent weakening of environmental agencies and legislation by the federal administration. This study investigated the effects of the deforestation of protected areas of Rondônia in southwestern Amazon Basin during the dry season. Two deforestation scenarios were constructed based on the level of protection against deforestation. In the first scenario, areas under moderate protection are deforested, while in the second, areas under moderate and high levels of protection are deforested.

Results indicate that the degradation of protected forests will result in substantial changes to the surface energy balance, whereby more of it will go towards sensible rather than latent heat flux. These changes in surface energy partitioning result in warmer and drier near-surface air, which is particularly evident in the afternoon. Following forest clearing, near-surface relative humidity drops on average by approximately 10% in the first and 23% in the second deforestation scenario.

Consequent changes to low-level wind circulation enhance moisture flux convergence and convection over the newly deforested areas, leading to enhanced rainfall in those areas. Rainfall increase by 40% in some areas in both deforestation scenarios. However, deforestation of protected areas also decreases rainfall up to 30% in the existing agricultural regions of the state, with potentially important negative impacts on agricultural production.