Optimising the spatial planning of prescribed burns to achieve multiple objectives in a fire-dependent ecosystem
Ensuring the safety of Australians living within fire-prone environments can be challenging due to the complexity of fire management. Factors such as time and budget constraints, the potential for a prescribed burn to escape, negative perceptions of the community, and conflicting objectives of different stakeholders. Damage to the ecosystem from burning too frequently or not frequently enough is another unpredictable risk. While asset-protection is an essential fire management objective, fire is also applied to the environment to ensure the ecological integrity of fire-dependent ecosystems. The following research brief has been developed in conjunction with land managers engaged in the implementation of prescribed burns.
Prescribed burning is a common action used to protect assets from wildfire damage. Prescribed burning will not necessarily prevent fire from occurring under extreme wildfire conditions but can have a positive localised influence on house survivorship by reducing fuel loads. Reducing fuel only in urbanised areas is considered an effective methodology for mitigating the risk of wildfire. However, studies have suggested that this may in fact exacerbate the likelihood of wildfire occurring based on increased fuel loads in surrounding areas. While burning at a high frequency may be effective at reducing fuel, a large homogenous burn increases the chance that a prescribed burn breaks containment lines, as well as having negative impacts on natural ecosystems. Land managers and scientists increasingly recognise the importance of identifying areas for burning that not only reduce fuel load around assets, but also reduce the overall fuel load of the system effectively.
A more effective strategy than current asset protection burn regimes may be to implement a regime that reduces the overall fuel load of an ecosystem, through the implementation of a heterogeneous mosaic burn. While likely being more effective as an asset protection protocol, there may also be added benefits for biodiversity. Decision support tools can also be used to optimise areas to implement a burn. Spatial analysis techniques are ever improving, and are capable of identifying priority areas for burning based on asset protection objectives and ecological concepts. We developed a decision-support framework for planning prescribed burning, and have applied this to the dry sclerophyll forests of southeast Queensland. We use mathematical optimization (Integer Linear Programming) to answer the question of when and where to burn. Our approach identifies spatially areas for burning based on asset protection objectives and ecological concepts. The team has quantified the trade-offs between asset protection and conservation objectives and show that it is possible to achieve good outcomes for conservation with minimal impact on asset protection. Their framework also improves asset protection by identifying a better distribution of prescribed burns in space and time. This work provides a transparent, objective and flexible framework that can be applied to many different prescribing burn scheduling problems at large spatial scales.