Avoiding Megafires

Bush Fire Front Occasional Paper No. 5

    Avoiding Megafires in Australia

The Bush Fire Front  April 2009

In the wake of the 2009 Victorian fire disaster the role of prescribed burning in relation to large wildfires (mediaspeak = megafires) has become a hot topic in the media, at academic seminars and on the internet. There have been numerous newspaper articles and TV grabs for and against the practice.

Prescribed burning is the planned use of low intensity fire, under mild weather conditions, to reduce fuel loads over broad areas of forested land.

On the one hand we have the “firies” (people with experience in bushfire management and firefighting) and people who have been directly affected by the fires. This sector is making very clear demands for greatly increased prescribed burning programs to prevent this sort of disaster ever happening again.

On the other hand we have a raft of academics and green activists giving their take on the issue. Their position is confusing, in that they say they support “targeted” or “strategic” prescribed burning, but oppose broad-acre fuel reduction. In general they oppose effective prescribed burning programs.

 A fair summary of their attitude is as follows:

1. Large intense wildfires are inevitable and are just something we have to accept as part of life, especially as a result of “global warming”.

2. Fuel reduction burning is useless, as it has no benefit in reducing fire intensity under severe fire weather.

3. Prescribed burning causes untold ecological damage. We don’t know what this damage is, but it is serious. Based on the precautionary principle we should not do it, or at least minimise its use.

4. People should not live in the bush at all, but if they do they should live underground, or at least be able to retreat underground whenever a fire approaches.

Let’s look at each of these points in turn.

Large wildfires are inevitable

This statement is, to put it politely, bosh. Large wildfires can only occur when there is a combination, at the same time, of three things:

      an ignition source,

      severe fire weather and,

      a large contiguous accumulation of fuel.

Remove any of these three and you cannot have a large wildfire.

We obviously can’t control the weather, nor can we hope to eliminate all possible avenues of ignition. The only factor we can control is the large contiguous accumulations of fuel. Therefore, broadscale fuel reduction burning is the only defence we have against large wildfires. This will not prevent fires occurring, but it will ensure fires are less intense, are easier and safer to control and will do less damage.

Does it work? Yes it does, as has been shown many times, over many years, by the experience of Western Australian forest managers. The “proof of the pudding” is the incidence of large wildfires in Western Australian forests over the last 50 years. There were a number of very large fires in Western Australian forests from 1900 to 1960, but after the 1961 Dwellingup fire disaster, the wide-scale fuel reduction program carried out by the then Forests Department, ensured that the fuel accumulation was well controlled. The graph below demonstrates this very clearly. It was only after the burning program gradually fell away following a diversion of resources away from forest areas, that the area of wildfires began to climb again after about 1990.

While the annual burn area was about 300,000 ha, it can be seen that the area of wildfires was at a minor level. Once the area slipped to the present average of about 200,000 ha the annual area of wildfire began to climb. So a certain minimum amount of prescribed burning is necessary to achieve a high level of protection. This idea of a threshold level of burning is missed by most people who are inexperienced about fire, and is the flaw in the argument that prescribed burning is OK so long as it is restricted to small areas around settlements.

The idea that large wildfires are an inevitable consequence of global warming is illogical. The fact is that if a proper system of fire management is instituted, involving efficient detection, good access, fuel reduction and an effective fire fighting force, the computer-generated predictions of future climate will add a new challenge, but will not make intense bushfires inevitable.

Fuel reduction burning is useless

A classic example of the effectiveness of a burning program in stopping a wildfire under severe weather conditions is given on this website at Fire Facts>The Value of FRB. The 1978 fire at Donnybrook, WA, occurred under very severe conditions. It began on farmland and was driven by a 130 km/h gale, caused by the errant tropical cyclone Alby, and headed directly for the town of Donnybrook. The fire ran into State forest and was stopped dead by a broad-acre 6-month old prescribed burn.

It is noteworthy that those who make the claim that burning is useless are mostly people with no practical experience in fire management. Their stance is purely ideological as they ignore the many years of on-ground experience of forest fire managers and the solid body of research that demonstrates unequivocally that fuel reduction burning does indeed reduce the impact and extent of wildfires.

A key issue, however, is the extent of fuel reduction burning. While some green organisations will accept some “targeted fuel reduction burning”, they are opposed to broadscale burning. If “targeted” means small buffer areas around settled areas then this is futile. Buffer burns like that will not stop large wildfires, as they will simply throw spot fires over the buffer zone. Worse still, this approach means abandoning the main forest area to the devastating impact of large wildfires.

Prescribed burning causes untold ecological damage

This is a common argument among academics and green activists, but in fact is just a speculation that fits their ideological stance. It is futile to call, as they do, for complete knowledge of every little impact of fire on every component of the biota.

What we do know, without any doubt whatever, is that Aboriginal burning prior to European settlement of Australia was all-pervasive over the continent (see Historical Accounts>Aboriginal Fire). Virtually anything that would burn did burn, and on the evidence of early European observers, the burning was done under weather conditions so that the fires were under full control. This could not have happened if fuel loads were high.  Indeed, there is convincing evidence that in the south west of Australia, at least, the frequency was about 2-4 years in the dry sclerophyll forest types. This practice, as well as the influence of lightning-caused fires, means that the biota in general is well adapted to fire – although some species have very specific requirements as to intensity and frequency.

We also know, and it was amply demonstrated again in Victoria in February 2009, that large high intensity wildfires have a devastating ecological effect. While we do not yet have any data from those fires, we do have some data from smaller wildfires in Western Australia that illustrate this point.

In 2003 there was a 25,000 ha wildfire at Mount Cooke, in the northern Jarrah forest, where post-fire evaluations were carried out. The fuel in most of the fire area was about 17 years old, carrying about 18 tonnes/ha of fuel. It was almost completely burnt out by a crown fire, and areas of bushland on Mt Cooke itself, regarded as fire refugia as they had not been burnt during three rotations of previous prescribed burning, were completely burnt-out by the high intensity fire. The photograph below shows the fire steaming up Mt Cooke, obliterating all in its path.


A post fire evaluation estimated that the fire had killed about 10 million of the overstorey trees outright. 10 million!! Whereas there had been multiple seral stages across the fire area before 2003, the fire reduced the whole area to one simplified seral stage. The BFF has not noticed any academic or green activist expressing any concern over this disastrous outcome.

People should not live in the bush, except underground

People like to live in the bush, have always done so and will continue to want to do so. Many thousands already live in the bush. It is true that these people should take special precautions to minimise the risks of being consumed in a bushfire. The necessary measures, in terms of planning and designing new residential areas, building houses that are appropriate for a fire-prone environment, and protecting existing houses are all well known, and can be implemented right now.

Putting people underground so that they survive bushfires is an unattractive option, suggestive of powerlessness and resignation. A far better solution is to manage the situation so as to minimise the risk. Furthermore, simply putting people underground ignores the damage done by bushfires to social and economic infrastructure left on the surface: the schools, churches, stores, roads, bridges, powerlines, railways and water supplies which are also vulnerable to high intensity fires.

The Bush Fire Front supports the principle of house construction to minimise bushfire risk, and the development of a safe haven within houses in bushfire prone environments. We also support the policy of Stay and Defend a Well Prepared House, or Leave Early.

But most of all we promote effective fuel management by prescribed burning, both of bushland in and around settlements, and on the broad-acres of forest beyond where massive fires do terrible environmental damage. Some people might choose to treat the Australian bushfire summer like a never-ending war-time blitz, retreating to the bomb shelters every hot windy day. There is a better, and far more attractive and effective alternative:keep the bush well burnt, and keep your house well prepared.