Assessing wildfire activity and forest loss in protected areas of the Amazon basin

Wildfires annually burn extensive areas in the Amazonia. Still, more is needed to know about the complex combination of triggering socioeconomic factors and environmental policies that motivate and explain the growing wildfire activity and forest losses. This study assessed wildfire occurrence, exposure, and transmission to natural forests in protected natural areas (n = 438) from 9 countries encompassing 140 million hectares of the Amazon basin. The fire ignitions and burned areas were first detected using remote sensing products from 2001 to 2018. We then conducted a wildfire transmission analysis to determine the neighboring fire source hotspots and land uses associated with human-caused ignitions encroaching on protected areas. Finally, we analyzed the environmental policies to understand the failure of such regulations to prevent the escape of fires burning large areas within protected sites. The results showed that recurrent wildfire hotspots cover a reduced portion but account for the bulk of the burned area. We found that, on average, wildfires burned 86,700 ha yr−1 of natural forests in protected sites, of which 10.5% corresponded to large incoming fires. Savanna and grasslands concentrated 29% and 41% of fire ignitions, where farmers and ranchers use fire periodically to clear extensive grazing properties. However, this high ignition density did not necessarily correlate with burned areas. The lack of a clear understanding of environmental policies and insufficient law enforcement was likely the main reasons for the continuous wildfire transmission to protected forests. The quantitative outcomes provide science-based criteria for detecting the high-priority areas within the Amazon where management efforts could help reverse the growing wildfire risk to protected natural forests.