Fuel reduction burning – misunderstood and irrationally maligned

 Fuel reduction burning – misunderstood and irrationally maligned

24 September 2009

published by www.sciencealert.com.au

Australia — Recently, the Victorian Government released a list of 52 localities expected to be most at risk from bushfires during the upcoming summer.

Question: What will be the safest places in Victoria this summer?

Answer: The areas that burned last summer.

Admittedly, the uncommon severity of last summer’s Black Saturday bushfires makes them a hugely exaggerated metaphor for the benefits of forest fuel reduction. Nevertheless, the burnt areas north of Melbourne graphically illustrate the point that if there is less to burn there is a correspondingly lower bushfire threat.

While this is simple common sense, it is widely misunderstood and is being irrationally branded as a “myth” in some quarters. Indeed, proposals for more fuel reduction burning are being routinely met with calls that the practice is both environmentally irresponsible and of little value for bushfire control.

These responses largely reflect a lack of public understanding about forest fire in general, and about the planning and conduct of fuel reduction burning (FRB) in particular.

Much of the public discussion of FRB in the mainstream media (where it is often erroneously referred to as “back burning”) has created an unreal expectation of it as a “magic bullet” that can somehow prevent bushfire and guarantee the protection of human life and property. Some of this misrepresentation has been driven by those most opposed to it. By building it up, they can more easily knock it down by highlighting examples of bushfire loss and damage adjacent to areas subject to recent fuel reduction burns.

In reality, the effectiveness of FRB in limiting bushfire damage is highly variable and dependent on a wide range of factors. These include the number of years since it was done, the size and configuration of the fuel reduced area, the degree of fuel reduction achieved, the prevailing weather conditions driving the bushfire, and its consequent intensity. Then there are separate, but highly influential factors such as the nature of private property and the bushfire preparedness of landowners.

Given the inherent variability of these factors it is ludicrous to suggest that FRB can guarantee the protection of life and property during bushfires. No forest management practitioner advocating its use has ever claimed otherwise. However, what can be said with certainty is that:

* communities located in close proximity to recently fuel reduced forests have a better chance of emerging unscathed from bushfire than if the same forests are long unburnt with heavy fuel accumulations;

* lower intensity bushfires passing through fuel reduced forests will do far less damage to soil, water and wildlife compared to high intensity fires burning in heavy fuel accumulations; and

* fire-fighting in fuel reduced forests is far easier and safer than in forests with heavy fuel accumulations.

Citing Black Saturday as a measure of the effectiveness of FRB – as many of its critics have done – is simply inappropriate. On that day, the fires were so large and their behaviour so extreme that relatively small and scattered fuel reduced areas were easily by-passed by long-distance spotting and could have no influence on improving the (already non-existent) capability to control them.

However, even under extreme circumstances, extensive areas of well-conducted FRB would somewhat reduce the development of crown fires and spotting thereby reducing environmental impacts and improving the capability to defend well prepared properties or provide residents with more time to safely evacuate. On the other hand, poorly prepared properties are indefensible and FRB would make little difference.

Burn severity mapping produced after the Black Saturday fires has clearly shown that low fuel areas had a pronounced impact on comparatively reducing the fire’s impact on environmental values. In addition, part of the fire was slowed and eventually stopped where it ran into the large consolidated area of fuel reduced forest that had been burnt by the 2006 Kinglake bushfires.

Fortunately, Black Saturday’s calamitous combination of ignition circumstances and extreme weather is exceedingly rare. The vast majority of summer bushfires burn under far milder conditions and the ability to quickly contain them is greatly enhanced where forest fuels are light. Conversely, fires burning in heavy fuel accumulations are more difficult to control even under mild conditions, and if able to burn for long enough may eventually develop into uncontrollable crown fires if the weather deteriorates. Clearly, the role of FRB in helping to prevent this benefits both the environment and the community.

FRB is not total fuel removal, yet too many people see the results of a hot summer bushfire and presume that FRB has the same environmental impact. In southern Australia, forest management agencies undertake FRB under mild conditions when fires generally burn with low intensity. The aim is to create a mosaic of burnt and unburnt ground. This is very different to the effect of a hot summer conflagration which consumes everything in its path.

Few critics seem to appreciate that FRB has evolved from the 1950s and is now a highly planned and tightly controlled forest management tool. Its use is limited to specific weather conditions at specific times of the year, using specific lighting patterns in specifically nominated areas with boundaries within which the fire is intended to be contained. Selected burn areas comply with regional Fire Management Plans strategically designed to prioritise fuel reduction based on the likely direction of major summer bushfires, the nature of forest and vegetation types, and associated environmental considerations.

Another myth from the FRB debate is that its proponents are advocating massive increases to the annual burnt area. In Victoria, the call for more fuel reduction burning is about restoring the practice to its former levels. In the 1970s and 80s, far more FRB was done. For example, at its peak in 1980-81, Victoria’s Forests Commission fuel reduced 477,000 hectares of public forest. This contrasts sharply with the Department of Sustainability and Environment’s current burn target of just 130,000 ha/yr – an area that is only occasionally achieved. Given that Victoria has over 8 million hectares of forest this represents only a modest commitment to preventative bushfire management.

It is acknowledged that the capability to restore FRB to these former levels will not be easy due to the social and demographic changes of the last 30 years. These include where we live, our attitudes to risk and increasingly litigious nature, the rise of the NIMBY phenomena, and romanticised and city-centric attitudes to nature. These factors are already constraining the capability of government land management agencies to effectively manage forest fire.

Where once, the planning and conduct fuel reduction burning was relatively straight-forward, there is now a myriad of bureaucratic requirements to ensure that all bases are covered, particularly if the operation doesn’t go as planned. These inherent planning and associated resourcing factors are magnified when burning in close proximity to townships and the urban fringe. Accordingly, disproportionate levels of effort and budgetary expense can be sunk into treating only very small areas in the most vulnerable locales. Further exacerbating these difficulties is the reality that Victoria’s land management agencies have lost much of their former field expertise in the planning and safe conduct of controlled burning.

Restoring preventative bushfire management to former levels of effectiveness will unquestionably require a considerable injection of government funding. This was presumably why the Victorian Government effectively dismissed the June 2008 findings of its own Parliament’s Natural Resources and Environment Committee which recommended a tripling of annual fuel reduction burning. Furthermore, the government’s unwillingness to acknowledge inadequacies in current public land management may explain the tendency for some of its senior figures to primarily attribute recent large bushfires to climate change. Hopefully these matters will be scrutinised by the Victorian Bushfires Royal Commission later this year.

There is a view that FRB is environmentally damaging. While unnaturally frequent cool burns could cause subtle ecosystem changes, the same can be said for unnaturally long periods between fire such is the reliance of so much of our flora on disturbance to stimulate regeneration. Importantly, these matters have been subject to scientific research for decades, although there is undoubtedly much more to be learnt. Critics of FRB should ponder the infinitely greater potential for environmental damage from unnaturally severe wildfires which are inevitable when long unburnt forests develop very heavy fuel accumulations – a threat that can be alleviated by FRB.

In terms of alternative fire management strategies, the opponents of FRB seem to fall into two distinct camps:

* those who abhor deliberate human intervention in nature and would prefer that all naturally-ignited forest fires are allowed to burn unhindered with a view to creating a steady state of low fuel levels throughout our forests; and

* those who favour the total exclusion of fire by a beefed-up emergency fire-fighting service largely compromised of super-sized aerial water bombers.

Those in the first camp include mainstream environmental groups and their supporters. Their position ignores the reality that there are now millions of people living permanently in and around Australia’s forests where previously there were few or none. Unlike the nomadic indigenous Australians, our society is now built on permanent settlement and material possessions. We simply can’t afford not to manage forests and fire if we wish to avoid losing human life and property. Consequently, while this “leave-it-to-nature” approach attractively mimics pre-1788 Australia, it is now wildly inappropriate.

The alternative notion that fire can be largely managed by concentrated expenditure on emergency bushfire suppression is unrealistic given the propensity for Australian forest fires burning in heavy fuels to become uncontrollable firestorms under the influence of hot, dry and windy weather.

Nevertheless, we have (together with the USA and parts of Europe) increasingly moved towards this model of massive expenditure weighted firmly towards emergency fire suppression at the expense of off-season, year round preventative activities such as FRB. However, with over 3 million hectares of Victorian forest burnt since 2003, together with the associated loss of human life and property in 2009, this approach is failing to deliver acceptable outcomes.

While there is an undoubted need for a high level of emergency bushfire suppression capability, it needs to be appropriately balanced against expenditure on preventative land management activities such as FRB. In the 1990’s when Victoria’s public lands were being managed with a somewhat better balance between fire suppression and prevention, a University of Melbourne study estimated that the State was gaining $24 of benefit in averted bushfire loss for every $1 spent by the responsible government land management agency. Not withstanding the influence of the current drought, it would be very interesting to see the results of a similar study undertaken today.

The reality is that we will always have bushfires, including occasional ones which are simply beyond control when they coincide with extreme summer weather. As we cannot control the weather or most of the means of fire ignition, forest fuels are the only factor that can be manipulated to reduce bushfire intensity. On this basis, the strategic use of fuel reduction burning should be embraced by the community as one of the few available tools that can minimise bushfire damage.

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