Modelling of forest fuel and weather effects on fire behavior in the oak forests of Southern Sweden

We modelled fire spread and fuel consumption as a function of fuel and weather conditions in Southern Swedish oak-dominated forests, using a dataset of 105 ignition experiments. We also tested whether regionally modelled and downscaled indices of fire weather provide a realistic assessment of fire behavior. Models fed with on-site weather data predicted 38% variability in fire spread and 68% in fuel consumption. Wind of 1.5 m/sec and above and the temperature of 15 degrees C and higher or the wind speed of 2.0 m/sec and above with relative humidity below 35% marked boundary conditions discriminating between situations with the rate of fire spread 1.03 m/min and those when a fire spread reached 1.38 m/min and above. Fuel water content (FWC) below 50% promoted fuel consumption. A higher proportion of oak fuels increased fuel consumption and was positively correlated with fire-line intensity, but did not affect the fire spread. The regionally modelled Duff Moisture Code (DMC) and the Fine Fuel Moisture Code (FFMC) were poor predictors of fire behavior during the experiments.