Assessing the effectiveness of prescribed burning in limiting the spread of future wildfires

Background. Prescribed burning is a widely-used fire management strategy for maintaining socioeconomic and ecological resilience by mitigating the impacts of wildfires. Monitoring the effectiveness of prescribed burns on future fire spread, however, is challenged by limited data availability and quality. 

Aims. We seek to create a simple, replicable approach to assess the likelihood of an unplanned fire being limited or contained by a previous fire using only feature boundaries. 

Methods. We first present methods to calculate the percentage of the back half of a feature boundary that was burnt in a wildfire encounter. We then model the through-burn probability against factors with known relationships to prescribed burn effectiveness and wildfire behaviour using 20 years of data for Victoria, Australia. 

Key results. We find that the likelihood of a prescribed burn limiting a subsequent fire is primarily constrained by a) the size of the prescribed burn, b) the presence of active control lines or roads, c) time since fire, and d) the weather during the encounter. 

Conclusions. We introduce a novel measure of barrier effectiveness and highlight the importance of thoughtful land management under ongoing climatic change. Implications. The simplicity of our proposed method is not limited to prescribed burns but can be used to measure the effectiveness of any barrier-wildfire encounter.