Following our recent Editor’s Choice that looked at prescribed burns in African savanna, this latest blog by Brooke Williams turns to fire management and prescribed burns in Australia. The blog supports Williams’ recent paper, Optimising the spatial planning of prescribed burns to achieve multiple objectives in a fire-dependent ecosystem.
Fire management is an important aspect of ensuring the safety of Australians living within fire-prone environments. It can be challenging due to many factors such as time and budget constraints, the possibility of a prescribed burn escaping, possible damage to the ecosystem from burning too frequently or not frequently enough, negative perceptions of the community, and sometimes conflicting objectives. 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.
Fire management since European settlement has dramatically changed the Australian environment. Previously fire regimes were influenced by indigenous practices, and by wildfire attributed to natural processes such as lightning strikes. During the 20th century, fire management was largely focused on the suppression of fire to mitigate the possibility of damage occurring to human lives and infrastructure. This however, has led to present day increases in fuel load, which have likely led to many wildfire disasters. Furthermore, as a result of climate change, extreme fire weather and wildfire is increasing. Drier and warmer weather results in higher than usual wildfire potential, as well as fire seasons extending beyond their historical range.
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 still 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 may break containment lines, as well as having negative impacts on natural ecosystems.
Fire management objectives often involve meeting a quota of land to be burnt. Priority locations for burning are identified largely through evidence-based triage. Research in the United States has shown that when difficult fire management decisions are being made, land managers will avoid risks. This has a tendency to lead to too frequently burning areas in close proximity to human infrastructure and not burning areas or suppressing fires outside of these areas. The latter can lead to intense wildfire events as an elevated fuel load within a system has been identified as contributing to some of the worst wildfire events in Australia, including Black Saturday in Victoria. Land managers and scientists 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 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. Using the Dry Sclerophyll Forest ecosystem of the City of Gold Coast, Australia, our recent study has shown that is it possible to achieve good outcomes for multiple objectives (asset protection and biodiversity) without increasing annual budgets. Broader use of systematic decision-making may greatly improve management outcomes.