Fire risk modelling for Kangaroo Island

Understanding changing bushfire risks to people, property and biodiversity is a key knowledge gap in many states and territories across Australia, including South Australia. In the wake of the 2019/2020 bushfires which had significant impacts on all three of these values across South Australia, understanding fire risks and potential fire impacts is crucial for making informed management decisions into the future. In our study we used a Fire Regime and Operations Simulation Tool (FROST) to model fire risk on Kangaroo Island over 50 years. We estimated the impacts of simulated fires on human life, property and biodiversity for three management scenarios (wildfires only and two prescribed burning scenarios). We found that prescribed burning resulted in a small decline in the frequency of wildfires compared to the wildfire only scenario and a lower frequency of both very high and extreme intensity fires. Despite a lower frequency of fires overall, the likelihood of very high or extreme intensity fires happening at least once over 50 years increased.

Despite reduced frequency of bushfires during wildfire seasons, exposure to people and property did not change between scenarios, probably because the extent of fires remained unchanged. Prescribed burning also resulted in a greater area burnt before minimum Tolerable Fire Interval (TFI) than wildfires alone. This is because prescribed burn efforts reduce the age classes of the remnant vegetation, resulting in the exposure of a larger proportion of vegetation below minimum TFI during the wildfire season.

These results present a preliminary understanding of fire risk on Kangaroo Island. The methods developed here could be applied to a range of case study sites in South Australia and may provide helpful estimates of future fire risk which could be incorporated into management decisions throughout the state.