Forest edge burning in the Brazilian Amazon promoted by escaping fires from managed pastures

Understanding to what extent different land uses influence fire occurrence in the Amazonian forest is particularly relevant for its conservation. We evaluate the relationship between forest fires and different anthropogenic activities linked to a variety of land uses in the Brazilian states of Mato Grosso, Para, and Rondonia. We combine the new high-resolution (30m) TerraClass land use database with Moderate Resolution Imaging Spectroradiometer burned area data for 2008 and the extreme dry year of 2010. Excluding the non-forest class, most of the burned area was found in pastures, primary and secondary forests, and agricultural lands across all three states, while only around 1% of the total was located in deforested areas. The trend in burned area did not follow the declining deforestation rates from 2001 to 2010, and the spatial overlap between deforested and burned areas was only 8% on average. This supports the claim of deforestation being disconnected from burning since 2005. Forest degradation showed an even lower correlation with burned area. We found that fires used in managing pastoral and agricultural lands that escape into the neighboring forests largely contribute to forest fires. Such escaping fires are responsible for up to 52% of the burned forest edges adjacent to burned pastures and up to 22% of the burned forest edges adjacent to burned agricultural fields, respectively. Our findings call for the development of control and monitoring plans to prevent fires from escaping from managed lands into forests to support effective land use and ecosystem management.