The ring of fire: the relative importance of fuel packing versus intrinsic leaf flammability

Abstract

Two different experimental set-ups were used to disentangle the relative importance of intrinsic leaf traits versus fuel packing for the flammability in fuel beds. Dried leaves from 25 Australian perennial species were burnt in fuel bed rings under controlled conditions. The flammability parameters were compared with the results of a previous study where individual leaves from the same species were burnt in a muffle furnace at 400°C. Fuel density (g fuel per volume) was the dominant driver for the combustibility and sustainability of the fire in the fuel bed rings; e.g., loosely packed fuel beds showed higher rates of spread. Specific leaf area (SLA, ratio of leaf area to dry mass) was not only the strongest predictor of “time-to-ignition” in the furnace set-up (higher-SLA species having shorter ignition times), but also played a major role in the build-up of the fuel bed, and thus the flammability in fuel beds.