Cerrado entre água e fogo: quantificação de traços de flamabilidade em comunidades vegetais ao longo do gradiente hidrológico

Abstract

ABSTRACT 1. Flammability is a complex and relevant functional attribute for understanding the ecological strategies that shape plant communities in fire-prone landscapes. Although humid environments are often considered fire-resistant, the role of this disturbance along hydrological gradients remains poorly understood. Trait-based approaches can provide insights into community assembly and functioning, as well as fire behaviour in these ecosystems. 2. This study aimed to quantify the variation in leaf functional traits related to flammability in plant communities distributed along a hydrological gradient connecting different Cerrado phytophysiognomies. 3. Plant communities were sampled along a continuous hydrological gradient encompassing different zones of vereda wetlands and cerrado sensu stricto. For the most representative species, the following functional traits were measured: live fuel moisture content (LFMC), leaf drying dynamics (area under the curve, AUC), ignitability, combustion sustainability, and temperature increase (ΔT). Traits were analysed at the community level using plot-weighted means and related to the relative distance of plots from the drainage line, used as a proxy for the hydrological gradient. 4. In the Principal Component Analysis, the axis explaining the greatest proportion of variance (PC1, 54.1%) showed a significant relationship with distance from the drainage line (β = 0.79), explaining 25% of the variation in plot scores. This axis was mainly structured by LFMC, AUC, combustion sustainability, and ΔT. The second component (PC2, 21.3%), dominated by ignitability, showed no significant relationship with the gradient. 5. The results indicate that flammability emerges from the integration of multiple functional traits and is partially structured by the hydrological gradient. Even plant communities located in the wettest vereda zones maintain trait combinations associated with residual flammability, indicating that the hydrological gradient modulates but does not eliminate fire occurrence potential. These findings contribute to Cerrado management and conservation by highlighting the importance of functional organization in predicting fire behaviour. Keywords: Functional ecology; Disturbance-dependent ecosystems; Water availability; Savannas; Palm swamps.