State-wide percentage targets for planned burning are blunt tools that don’t work
Fire profoundly influences human health, the economy and wildlife. In Victoria, for instance, bushfires have burned more than one million hectares since 2009, claiming 178 lives and more than 2,300 homes, and causing more than A$4 billion in social, economic and environmental costs. And, as highlighted by recent devastating fires in the United States and South Africa, effectively managing fire risk is a global challenge.
To reduce fire risk, the 2009 Victorian Bushfires Royal Commission recommended that the Victorian Government aim to burn at least 5% of public land as an annual rolling target. The Inspector-General for Emergency Management is currently reviewing this simple percentage target against a new risk-based approach to bushfire management.
Is a state-wide percentage target the best way to reduce risk to human life and property and maintain our globally significant biodiversity? We think not.
Limitations of percentage targets
Across the world, planned burning is the main tool for reducing bushfire risk. It is effective when used in key locations by reducing fuel loads, which in turn reduces fire spread rate and intensity. Appropriate planned burning can also manipulate native vegetation to benefit certain plant and animal species.
But burning 5% of public land each year (390,000 hectares in Victoria’s case) has three main limitations.
“It’s time to drop the simple 5% target. It is a blunt tool, and a risk-based approach more effectively focuses fire protection where it’s most needed.”
1. It causes biodiversity to decline
Many native plants and animals rely on fire to regenerate habitat and maintain populations, but too much fire can be bad. Consider the three animals pictured in Figure 1.
Our new research, published in the journal Ecological Applications, shows that burning 5% of public land each year will harm biodiversity in the mallee shrublands and woodlands of north-western Victoria (Giljohann et al, 2015). We used stochastic dynamic programming to model how fire changes vegetation in the presence of both planned burning and bushfires, using an extensive data set of birds, small mammals and reptiles. We found that burning 5% of a given area increases the risk of extinction of a range of native species. This is because, while some species prefer more recently burnt vegetation, most fire-sensitive species occur in older vegetation, which is largely eliminated when burning 5% each year.
To date, this is the only peer-reviewed paper that predicts how Victoria’s current burning strategy influences wildlife diversity.
2. It overlooks important differences between ecosystems
Ecosystems across Victoria are not uniform. They contain different plants and animals, they have different fire regimes, they have different fuel loads, and they present different fire risks to humans. A simple, state-wide target covering such a large and diverse area inevitably misses these important details.
Put simply, what might be an appropriate fire regime for one ecosystem (such as a forest or woodland) is very different to an appropriate fire regime for another (such as a grassland or heathland).
3. It is inefficient
The current percentage-based strategy does not focus enough on the most at-risk Victorian communities. Large-scale planned burning in remote areas, such as the Murray Mallee region, makes it easier to achieve the state-wide planned burning target. But it is an inefficient use of resources, and does little to reduce the risk of major bushfires to human life and property.
Research completed after the 2009 Black Saturday fires showed that the most effective way to protect houses is through burning (or clearing) vegetation in close proximity to properties (Gibbons et al, 2012; and see Decision Point #56, p6-8).
In this case, burning in more remote regions had relatively little impact on house loss after a major bushfire
A state-wide target, in contrast, encourages burning in remote locations where the benefits can be negligible and fire-management resources wasted.
A more effective plan
The Victorian Bushfires Royal Commission also recommended that the Victorian Government develop risk-based performance measures for bushfire management. In response, the Department of Environment, Land, Water and Planning has developed sophisticated methods for mapping risks from major bushfires across the state, and predicting bushfire risk following planned burning.
We strongly support this more sophisticated, regional risk-management approach. After all, planned burning to protect human life and property should naturally focus on places where people are at most risk from major bushfires.
But what about also considering wildlife? Recent research we have undertaken offers a way to predict how planned burning influences risks to biodiversity (Kelly et al, 2015). We developed a method for determining the optimal fire history of a given area for biodiversity conservation by linking tools from three fields of research: species distribution modelling, composite indices of biodiversity, and decision science. By clearly defining fire management objectives based on the habitat requirements of fire-sensitive species in a community, this approach could be used to maximize biodiversity in fire-prone regions and nature reserves. This will allow land managers to consider the trade-off between protecting people and conserving wildlife when applying planned burning.
Just as the 5% target is an inefficient method for minimising the impact of major bushfires on human life and communities, it also has negative consequences for the resilience of natural ecosystems.
To be clear, we are not advocating a blanket approach of less (or more) planned burning. We are saying that a mix of strategic and broad-scale planned burning should be done so as to make the biggest reduction in risks to people and wildlife. That is not best achieved by a state-wide target.
It’s time to drop the simple 5% target. It is a blunt tool, and a risk-based approach more effectively focuses fire protection where it’s most needed: safeguarding people and wildlife.
This article is an edited version of an editorial that appeared in The Conversation https://theconversation.com/percentage-targets-for-planned-burning-are-blunt-tools-that-dont-work-39254
Gibbons P, L van Bommel, AM Gill, GJ Cary, DA Driscoll, RA Bradstock, E Knight, MA Moritz, SL Stephens, DB Lindenmayer (2012). Land Management Practices Associated with House Loss in Wildfires. PLoS ONE http://dx.plos.org/10.1371/journal.pone.0029212
Giljohann KM, MA McCarthy, LT Kelly & TJ Regan (2015). Choice of biodiversity index drives optimal fire management decisions. Ecological Applications 25, 264–277.
Kelly LT, AF Bennett, MF Clarke & MA McCarthy (2015). Optimal fire histories for biodiversity conservation. Conservation Biology 29, 473–481.