Dinâmica espacial dos incêndios florestais em Autazes, Amazonas

Abstract

Wildfires cause great disturbance in the Amazonian forests. Their occurrence results from an interaction between climatic conditions and land-use and land-cover change. In El Niño years, the climate becomes drier and hotter in some parts of the Amazon region, such as central Amazonia, and wildfires affect large areas of forest causing environmental, climatic and socioeconomic impacts. Understanding of wildfire dynamics and their relationship with landcover change is important for mitigating wildfire effects. A useful tool in this process is dynamic modeling of spatial data, which, through simulation of future scenarios, can provide information for planning of prevention policies. The goals of this research were to map fire scars and deforestation over a period of 31 years in the municipality (county) of Autazes (in central Amazonia), to simulate the occurrence of these disturbances over the 2015-2025 period based on the historical data, and to estimate the loss of biomass caused by these disturbances. Mapping of fire scars was done visually using Landsat and Resourcesat images. Data on deforestation were obtained from INPE/PRODES. The simulations were performed using spatial-dynamics models in DINAMICA-EGO software. Biomass loss was estimated by multiplying the simulated areas of deforestation by the biomass densities of the impacted forests and, in the case of biomass losses from wildfire, the simulated area of fire scars was by multiplied both biomass and a tree-mortality factor. Forest fires occurred only in 1997/98 and 2015/16, which were years of strong El Niño, besides 2009/10 that was less strong that the others. The simulated area of wildfires was approximately 85% greater than the deforestation area. Total simulated biomass loss was approximately 4.066 Gg from deforestation and approximately 903 Gg from wildfire. We conclude that forest fires in Autazes are related to strong El Niño events and that wildfire is responsible for degrading a larger area than deforestation, although biomass loss is mainly from deforestation.