Determining transitions in fuel hazard in Tasmania's lowland

Heathlands are considered highly flamable communities within which fire behaviour is difficult to predict. Knowledge of fuel hazard within these communities is essential for fire suppression and minimising the risks of wildfire. Fuel hazard rating systems have the potential to provide efficient and accurate predictions of the ease of suppression of wildfire. These have largely been developed in forest systems, up until recently where they have been developed for multiple fuel types. The ability of the latest fuel hazard rating system, the DSE overall fuel hazard guide, is tested to see whether it accurately describes fuel hazard in Tasmania's lowland heathlands. The result of the guide were compared to previously used indicators of fire behaviour, including fuel load, percent dead, shrub height and continuity of the fuel. The DSE overall fuel hazard guide was not found to adequately describe fuel hazard in heathlands, due to low correlation scores between the fuel variables. To further understand fire behaviour in heathlands, fuel hazard was examined against age and environmental variables to identity when and in what conditions fuel hazards exists. A mulitple variable regresion analysis indicated that time since last fire, annual precipitation, mean temperature of the warmest quarter, mean temperature of the coldest quarter and soil organic content best predicted fuel hazard (r2+ 53.2%, p< 0.001). A threshold between low intensity fires and high intensify fires was identified at 11.5 years, but this threshold changed within the influence of environmental variables. A decision tree allows managers to use easily obtained inputs to predict heathland fuel hazard and determine whether fuel managment actions are necessary, is presented.