Isarithmic analysis of forest fire fuelbed arrays

Isarithmic analysis, a cartographic technique, was used for mapping two structurally distinct forest fire fuelbeds. Method-produced errors and statistical validity of isarithmically-created surfaces for fuel loadings and depths were determined and analyzed. The isarithmic method-produced error is a function of data sampling scheme, spatial interpolation model, and spatial variability of the phenomenon mapped. Using an unaligned stratified random design and kriging interpolation, error produced by the isarithmic method was proportional to (sample size)−0.20 times an intercept coefficient that directly reflected variance of each fuel parameter interpolated. As a result, the magnitude of error decreased, at a decreasing rate, with increasing sample size; fuel parameters that exhibited high spatial variability also had higher magnitudes of error due to larger intercept values. Four or nine sample points were too few for use in the isarithmic mapping of the fuel types examined and a minimum of sixteen points was required. The analytical scheme presented here could yield more reliable information on the elements that compose the forest fire environment.