The fire regimes of the Cerrado and their changes through time.

The Brazilian Cerrado is a heterogeneous region of open ecosystems adapted to fire intermingled with patches of woody growth-forms, with high levels of biodiversity and endemism. In recent decades, land conversion and human activities have proliferated across the Cerrado, losing about half of its original area. These changes, coupled with climate change, are altering its fire regimes with uncertain, but possibly adverse, consequences for Cerrado ecosystems. Here, we used burned area data to characterize the fire regimes of each cell on a 30 km grid over the Cerrado, and used a spatially constrained hierarchical clustering approach to delineate the regions with different fire regimes in four consecutive 9-year periods between 1985 and 2020. Comparing the periods 1985-1993 and 2012-2020, we found substantial changes in the number and shape of the fire regime regions, and in their fire characteristics. The main factor differentiating these regions was their level of fire activity: some showed large, numerous and frequent fires, while others showed small, few and infrequent fires. We also identified a region in the north with a later peak of the fire season, characterized by small but numerous fires. Finally, we found that while the fire activity of the southern areas of the Cerrado substantially decreased, fire activity levels in the centre and north increased or remained high over time.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.