Como a dinâmica ambiental de fogo, inundação e sazonalidade alteram a inflamabilidade de plantas no Pantanal, MS

Abstract

Flammability, in the context of plant functional traits, refers to the ability of plants to ignite and sustain burning, and it can both be influenced by and influence fire characteristics and regimes. In the Pantanal wetland, a biome characterized by periodic cycles of flooding, drought, and fire, these environmental filters can strongly affect plant flammability. The objective of this study was to analyze how seasonality, timing of prescribed burns, flood level, and flood events affect plant flammability in the floodplain grasslands of the Pantanal. The study was conducted in the Miranda and Abobral regions of the Pantanal. Prescribed burns were conducted in permanent plots at different times of the year, and individuals from the most dominant plant species were collected during the dry season (July), rainy season (November), and after a flood event. Flammability was assessed at the species, at groups (grasses vs. non-grasses), and community levels. We measure ignition, average and maximum burning temperatures, time to ignition, flaming duration, combustibility, and consumability. Seasonality was the main factor associated with changes in flammability, with lower mean and maximum burning temperatures and higher ignitability observed in the dry season. Other trends included a reduction in flaming duration after flooding, and variation in combustibility and consumability. Plants exposed to prescribed burns before the dry season exhibited lower maximum burning temperatures, consumability, and combustibility. In contrast, plants in areas with higher flood levels displayed higher mean burning temperatures and consumability, and lower combustibility. These findings indicate that both seasonality and burn timing are key predictors of plant flammability. Thus, integrated fire management may be an effective strategy to regulate these seasonal changes and reduce environmental flammability. Additionally, areas with higher flood levels may experience more intense burns, driven not only by greater biomass accumulation but also by increased plant flammability.