Flammability Evaluation of Native Brazilian Amazon Rainforest Leaves

The Brazilian Amazon Rainforest is home to a vast number of fauna and flora species and plays a crucial role in mitigating the effects of global climate change. Despite its importance, the biome has been severely impacted by wildfires for years. Fuels are the most critical element in wildfire management, and leaves are the combustible particles present in all potential layers of fire spread. This paper presents the flammability evaluation of oven-dried live leaves from 24 native tree species of the Brazilian Amazon Ombrophilous Dense Forest, using the mass-loss cone calorimeter (MLCC) at 50 kW/m². Additionally, through hierarchical clustering analysis, species were grouped into five flammability clusters. The interquartile range (IQR) of the cone calorimeter parameters—PHRR, THR, and TPHRR—was the difference between 67.90 and 61.03 kW/m²; 5.93 and 5.50 MJ/m²; and 33.67 and 29.58 s, respectively, showing a smaller variation than that reported in live leaf cone calorimeter test literature (both dry and fresh). A clear distinction was also observed between palms and other species with compound leaves. While palms—Leopoldinia piassaba, Oenocarpus bacaba, and Phytelephas macrocarpa—were classified into the flammable, highly flammable, and Extremely Flammable groups, respectively, other species with compound leaves were grouped into the low flammable (Pentaclethra macroloba) and very low flammable groups (Anadenanthera colubrina and Parkia pendula). Finally, the results have the potential to improve predictions of Brazilian Amazon wildfire behavior and inform the selection of less flammable species for green belts or reforestation projects.