Fire dynamics in the South American Chaco and their link to agriculture and drought

Abstract Fire is a key process in tropical dry woodlands and savannahs, shaping their vegetation and ecological functioning. Yet, fires in these systems are increasingly a major sustainability concern, causing carbon emissions, biodiversity losses and human health impacts. Land-use change can lead to fewer fires (for example, through fire suppression) or more fires (for example, fires used for pasture management or land clearing), and climate change amplifies fire dynamics through hotter and drier conditions. Here we uncover a tight coupling between agriculture and drought as drivers of fire in the Gran Chaco. We reconstruct detailed fire histories from satellites to reveal that most of the Chaco (~65%) has experienced burning since 1985. Patterns of fire, land use and drought show that the majority of fires are attributable to either agricultural expansion into forests or pasture management and that such fires become frequent during drought. Overall, this challenges the notion that intensifying droughts are a principal driver of changing fire regimes in tropical woodlands and savannahs.