Improved laboratory method to test flammability metrics of live plants under dynamic conditions and future implications

Abstract

The role of live vegetation fuel properties in altering fire behaviour is increasingly being recognised. The techniques utilised to assess how fuel characteristics impact fire behaviour, however, use apparatuses that do not accurately represent the exposure of plants to fire. This study presents a replicable and precise laboratory method of testing flammability metrics in live vegetation, particularly Acacia floribunda, Cassinia arcuata and Pinus radiata. Two heating regimes were tested – a static heat flux to reflect current methods and a dynamic (increasing) heat flux to more accurately replicate an approaching fire front. Piloted ignition and autoignition were used for both heating regimes to test the effect of different ignition mechanisms on flammability metrics. The pilot igniter increased the number of samples that reached flaming ignition, and decreased the time and energy required to reach all flammability metrics. Significant differences were observed between heating regimes, suggesting it is important to test flammability of live plants under a dynamic heating regime that most accurately replicates an approaching fire front. Adoption of this methodology is recommended to ensure more realistic and standardised data on flammability of individual plant species and plant communities. This will lead to better-informed and more accurate wildfire behaviour modelling.