O processo de degradação florestal associado à exploração ilegal de madeira na Rodovia BR-319

Abstract

The conservation of the Amazon is a challenging task under severe climate changes and in the face of government policies that threaten the forest. The paving of the Manaus – Porto Velho highway (BR-319) is one of the main political discussions on the conservation of the Brazilian Amazon. The highway connects the region of the arc of deforestation with the largest blocks of conserved forest located in the west of the Amazon. This study aimed to understand the forest degradation associated with illegal logging in the context of the dynamics of carbon stocks in forests under the influence of BR-319. We investigated whether land ownership classification and distances from the BR-319 and the new logging frontier (Vila Realidade) influenced the dynamics and changes in the stock of biomass and forest necromass over a 9-year interval. In a 320 km transect along the BR-319, 20 permanent forest plots of 1 ha were evaluated. To verify the stocks and dynamics (losses and gains) of biomass and dry necromass, data from two censuses sampled in different periods (2010 and 2019) were used. Illegal logging took place in three plots on registered rural properties and was responsible for an average loss of 10% of biomass and an increase of 234% in forest necromass. The proximity to the BR-319 highway explained 39% of the change in forest biomass and the proximity to Vila Realidade explained 40%. The change in forest biomass showed a trend of -24.79 ± 20.76 Mg ha⁻¹ loss in logged areas and +7.54 ± 11.47 Mg ha⁻¹ gain in conserved areas. The explored area presented annual loss by mortality 2 times greater than the conserved area, while the gain by recruitment and growth presented a similar value between illegal logging and conserved areas. The net balance between losses and biomass gains observed in the illegal logging plots was negative -2.60 (±2.64) Mg ha⁻¹ year⁻¹. Such results indicate that the areas illegal logging in the BR-319 are losing more carbon than they are absorbing, even before the region experiences pressure for deforestation with paving.