Importance of fuel treatment for limiting moderate-to-high intensity fire : findings from comparative fire modelling

Context: Wildland fire intensity influences natural communities, soil properties, erosion, and sequestered carbon. Measuring effectiveness of fuel treatment for reducing area of higher intensity unplanned fire is argued to be more meaningful than determining effect on total unplanned area burned. Objectives: To contrast the relative importance of fuel treatment effort, ignition management effort and weather for simulated total area burned and area burned by moderate-to-high intensity fire, and to determine the level of consensus among independent models. Methods: Published and previously unreported data from simulation experiments using three landscape fire models, two incorporating weather from southeastern Australia and one with weather from a Mediterranean location, were compared. The comparison explored variation in fuel treatment and ignition management effort across ten separate years of daily weather. Importance of these variables was measured by the Relative Sum of Squares in a Generalised Linear Model analysis of total pixels burned and pixels burned with moderate-to-high intensity fire. Results: Variation in fuel treatment effort, from 0 to 30 % of landscape treated, explained less than 7 % of variation in both total area burned and area burned by moderate-to-high intensity fire. This was markedly less than that explained by variation in ignition management effort (0–75 % of ignitions prevented or extinguished) and weather year in all models. Conclusions: Increased fuel treatment effort, within a range comparable to practical operational limits, was no more important in controlling simulated moderateto- high intensity unplanned fire than it was for total unplanned area burned.