Fires in the cerrado, the Brazilian savanna

Abstract

The cerrado is the largest area savanna formation in South America, and originally covered approximately 25% of the Brazilian territory. The savanna forms of cerrado are characterized by a ground layer of grasses, small palms, shrubs, and trees. During the wet season there is a high production of biomass that dries as the dry season progresses, favoring the occurrence of fire. For thousands of years, natural fires, during the wet season, and anthropogenic fires, during the dry season, coexisted in the cerrado region. suggesting that fire, together with the seasonality of rainfall and the poor nutrient soils, is one of the determinants of the cerrado vegetation form. Cerrado fires can be characterized as surface fires, consuming basically the fine fuel of the herbaceous layer. Most species of the herbaceous layer are highly resistant to fire and resprout a few days after a fire. For open form s of cerrado, nine months after a fire, dead biomass (grasses+litter) represents 65% of the total, suggesting that it is possible to have a sustained fire, even during the short dry spells of the next rainy season. Th e woody vegetation presents several adaptive characteristics, such as thermal insulation o f live tissues and the presence of underground organs that store water and nutrients. However, fire frequency and time of fire affects the structure and species composition of cerrado’s woody plant communities. In this chapter, we present a review of cerrado fire ecology, with emphasis on fire behavior, changes in the structure and composition of the vegetation, and its effects on water use and carbon flux.