Ignite Success with the 2026 Prescribed Fire Test – Spark Your Firefighting Future!

Duff is the organic litter layer on the forest floor that acts as both fuel and an insulating barrier. Because of this, its thickness and moisture determine how much energy the fire can release at the surface and how that energy moves downward. A thick, dry duff layer provides substantial fuel and surface heat, which can influence how deeply the fire heats into the soil and how heat is conducted through the layer. A moist or thick duff layer can absorb and slow heat transfer, insulating the mineral soil, while a lighter or drier layer may allow more heat to reach the soil if the surface fuels burn through. All of this together shapes burn depth, how heat is transferred, and the resulting effects on the soil, making duff a key factor in those aspects of a prescribed burn.