Development of burn prescriptions using quantitative expert judgement

Prescribed burning is carried out within a predetermined set of weather conditions-known as the burn prescription-that supports safe and effective operations. These prescriptions are often informed by expert knowledge, particularly the experiential insights of burn practitioners. However, ad hoc approaches to eliciting such expertise lack the rigour required to produce reliable prescriptions. Recent advances in structured elicitation methods offer more robust and transparent methodologies. This research explored the use of structured elicitation techniques to develop new burn prescriptions for native forests and woodlands in Victoria, Australia. Local fire managers identified two priority burn outcomes: a mixed severity, patchy burn, and a high severity, high coverage burn. Our elicitation was designed to develop prescriptions specific to these burn outcomes across five vegetation scenarios with different fuel hazards. The elicited prescriptions for achieving a mixed severity, patchy burn were wetter and less windy than those for a high severity, high coverage burn. Fuel hazard had little influence on the prescribed conditions. The new prescriptions resulted in a 40 % increase in the burn window for achieving a high severity, high coverage burn compared to current prescriptions. In contrast, the burn window for the mixed severity, patchy burn changed little. Thus, achieving a patchy burn may require adjustments to other aspects of burn implementation, such as ignition techniques. Workshop participants described how they modify their ignition approach to manipulate fire behaviour and resulting burn outcome. This study demonstrates how quantitative expert judgement can harness the experiential knowledge of burn practitioners to develop burn prescriptions. Field testing is recommended to further refine these prescriptions.