Coherence of Recurring Fires and Land Use Change in South America

Fire events in South America are becoming more extensive and frequent as climate extremes and human pressures increase, and even repeatedly occurring in some areas within decades. However, the relationship between recurring fires and vegetation dynamics remains unclear. Here, we extracted the number of fire occurrences using burned area satellite product and analysed the relationship between recurring fires and vegetation dynamics with remote sensing land use and vegetation index datasets in South America. We show that approximately 1.39 x 106 km2 of burnt area has experienced recurring fires during 2001-2020. More than half of burnt area of recurring fires occurred in savannahs with remaining burnt area in grasslands, forests and croplands. Although forests tended to be less susceptible to recurring fires among all vegetation types, their coverage loss with recurring fires was the greatest. The greater proportion of forest conversion to croplands concurred with more recurring fires. Conversely, the coverage of croplands and grasslands gained the most with recurring fires. In the areas without vegetation conversion, more frequent recurring fires further suppressed canopy greenness and density, even in fire-adapted savannahs and grasslands. Our results suggest that recurring fires and land use change are generally coincident, reflecting the intense pressure of human activities on natural vegetation in South America. Thus, coordinated efforts on vegetation conservation and sustainable management of human-induced burning in the region are urgently needed. Fire occurrences during 2001-2020 were quantified from satellite data in South America. Recurring fires concur with land use change, and more frequent fires correspond to greater vegetation conversion for anthropogenic uses. The canopy of surviving vegetation from more frequent fires is more severely damaged. image