Aerial and surface fuel consumption in crown fires

An empirical model is presented which relates fractional reduction in loading to fuel element diameter and moisture content for surface and aerial fuels consumed near the fire front in a spreading crown fire. The model is based upon data from a series of experimental crown fires in immature jack pine. Its intended use is to permit calculation of fuel consumption per unit area (kg/m(2)) needed to estimate edge intensity (kW/m) from the spread rate of a crown fire. Model predictions of small fuel component fractional loading reduction had a root-mean-square error of almost 0.2 for our calibration data set. Most of the error arises from the model prediction of complete consumption of crown foliage, some of which was not exposed to flame in the fires of our data set. The model does not address the longer term burning of duff and large woody fuels.