Wildfire risk management across diverse bioregions in a changing climate

Wildfire risk-management needs to consider interrelated factors that influence fire regimes, including changing climate and sometimes conflicting stakeholder priorities. With wildfires increasing in size and intensity over recent decades, wildfire risk management is becoming more important and more complex. For southwest Australia, wildfire risk-management is predicated on a longitudinal study of the relationship between prescribed burns and wildfires from 1953–2004 over a subset of this biodiverse region. Our study replicates the methodology of the longitudinal study, applying it to the wider region and extending the analysis to 2021. We found the extrapolation of the longitudinal study’s findings to the wider region invalid, as was extrapolation beyond 2004. In particular, the area of prescribed burns generally had negligible influence on wildfire area. However, more spatially complex fire history was strongly correlated with lower probability of large wildfires (independent of area burned). This highlights the limitation of extrapolating wildfire risk-management policies to areas of differing vegetation and/or climate, including changing climate over time. The potential of indigenous-led practices for wildfire risk and biodiversity conservation, particularly for areas with high spatial variability, is apparent as is the need for alternative strategies to prescribed burning as the primary tool in wildfire-risk mitigation.

野火风险管理需综合考量影响野火发生动态（fire regimes）的各类关联因素，涵盖气候变化以及时常存在冲突的利益相关方优先级诉求。近数十年来，野火的规模与烈度持续攀升，野火风险管理的重要性与复杂程度亦同步提升。针对澳大利亚西南部区域，野火风险管理的制定依托于一项针对该生物多样性区域内部分片区1953年至2004年期间规定火烧（prescribed burn）与野火间关联关系的纵向研究。本研究复刻了该项纵向研究的方法体系，将其应用于更广范围的区域，并将分析时段延展至2021年。研究结果表明，将该纵向研究的结论外推至更广区域的做法并不成立，在2004年之后进行外推同样缺乏有效性。具体而言，规定火烧的总面积通常对野火蔓延面积的影响微乎其微。然而，空间结构更为复杂的火历史记录，与大型野火发生概率的显著降低存在强相关性（与已火烧面积无关）。该研究凸显出，将野火风险管理政策外推至植被与气候条件存在差异的区域时存在局限——其中亦包含随时间推移发生的气候变化。本土主导的野火风险管理与生物多样性保护实践展现出了应用潜力，针对空间变异性较高的区域而言尤为如此；同时，替代规定火烧作为野火风险缓解核心手段的策略开发，亦存在迫切需求。