Fact Sheets

This section contains several brief Fact Sheets that explain various aspects of fire management that are likely to be of interest to the general public.

The current Fact Sheets are as follows:

1. Aims of the Bush Fire Front
2. Fuel Reduction Burning and Biodiversity
3. What is Fuel Reduction Burning?
4. Does Fuel Reduction Burning Prevent Bush Fires?
5. Wildfire and Water Catchments
6. What are the Alternatives to Fuel Reduction Burning?
7. Management Options for Fire in South West Forests

8. The Critical Importance of Expertise and Experience in Fire Management

 1. The Aims of the Bush Fire Front

The Bushfire Front is a small, incorporated, organisation dedicated to minimising bushfire damage in Western Australia. We are independent of government or any institution, our only links being to similar independent organisations in the Eastern States.

Our membership comprises professional bush fire specialists, fire scientists and community representation. We have decades of experience in all aspects of bushfire management, from legislation and governance, to fire safety, fuel reduction and fire fighting. All of us have been involved, and are still involved in the challenging business of bush fire management.

The Bush Fire Front was formed in 2002 when it was realised that the standards of fire management in Western Australia had slipped to a dangerous low. We recognised the worst possible combination of conditions:

  • The climate was getting drier and possibly hotter, while bush fire fuels were no longer being effectively reduced.
  • There was a massive expansion of the population into bush fire vulnerable areas like the Perth Hills and the Leeuwin-Naturalist region, at the same time that fire fighting manpower was declining.

We detected a dangerous change in attitudes. The government was complacent, or denied there was a problem.  The community was ill-informed about fire, or believed that if a fire came they would be OK, as the firefighters or the water bombers would turn up. This ignores the fact that water-bombers are ineffective against crown fires, and cannot operate at night.

Since 2002 the Bushfire Front has made strenuous efforts to raise the interest of the authorities in improved bushfire management, and to educate communities. We have written dozens of submissions, newspaper articles, given papers to conferences, met with Ministers and senior agency staff. We have organised community forums and supported bushfire brigades and Bush Fire Ready groups.

Our key messages are:

  1. Once a bushfire crowns, that is, starts to burn through the tree canopy rather than along the ground, no force of firefighters on earth will stop it. Crown fires in eucalypt forests throw spot fires (burning embers) kilometres down-wind, and fire intensity and speed overwhelms human effort.
  2. There is only one way known to science and experience to stop a crown fire: this is to reduce the fuel in front of the fire. When a crown fire runs into an area that has been recently prescribed burned, the fire drops to the ground, and can be effectively tackled.
  3. Our bushfire management system must focus equally on the three basic elements: preparedness, damage mitigation and fire fighting.  To focus only on the third element is a recipe for disaster.... tragic experience has demonstrated time and time again that bush fires in heavy fuels under hot dry conditions are simply unstoppable. Preparedness and damage mitigation are the two forgotten elements of bushfire management.

Some environmentalists claim that fuel reduction  burning destroys the ecosystem, and that large hot killer“ fires are an acceptable alternative. This view is not only cruel and heartless, it flies in the face of science and experience. It also ignores the fact that Aboriginal people burned the bush regularly for thousands of years before Europeans came along with their inappropriate and out-dated European attitudes.

2. Fuel Reduction Burning and Biodiversity

“Protection of biodiversity” is often used as an argument against prescribed burning by green activists. It sounds plausible, but is really a red herring.  Fire is a natural and inevitable part of the Australian environment, and nowhere more so than in Western Australian forests.

Quite apart from ignition by lightning since primeval times, the arrival of humans about 40,000 years ago led to regular burning by the aborigines. Aboriginal oral traditions, supported by scientific evidence, is that they almost always had a fire going somewhere in the forest, even in midsummer, but they did no serious damage because the litter cover was so light, due to frequent burning. The fires were mild in intensity and patchy in extent. The evidence suggests that over most of the forest area, except for refugial areas like swamps and rock outcrops, the frequency of burning was about 4 years.

This means that the current assemblage of flora and fauna in Western Australia evolved to tolerate this fire regime. Therefore, a burning regime that simulates this approach should have no detrimental effects on biodiversity, provided the burns oscillate between spring and autumn seasons. Fuel reduction burning is designed to protect the whole forest ecosystem from high intensity wildfires, as well as achieve some silvicultural objectives. Virtually no trees die in a fuel reduction burn.

What is highly detrimental to biodiversity, both terrestrial and aquatic, is a high intensity wildfire burning in heavy fuels. In contrast to a low intensity fuel reduction burn, which is usually designed to cover only about 70% of an area, a high intensity wildfire will burn everything in its path, wiping out any refugial areas. Large numbers of trees will be killed and the forest environment, so critical to many aspects of biodiversity, is adversely affected for decades to come. This was graphically demonstrated in the two recent wildfires near Perth, The Mt Cooke fire of 2003 and the Perth Hills fire in 2005.

The clinching argument is that no scientific research has been able to demonstrate that a 5-7 year burning rotation in the northern jarrah forest, as practised from 1961 to 1985, was had any detrimental effect on “biodiversity”. Large areas of the jarrah forest are now in national parks or other reserves. If that burning regime was so bad, how come the forest was good enough to place in such a reserve?

3. What is Fuel Reduction Burning?

Fuel reduction burning (FRB) is burning the forest under mild conditions so that excess fuel (leaves, twigs, branches and some scrub on the forest floor) is largely removed without harming the biodiversity.  It is a common misconception that a FRB covers the entire area. In reality, patches of unburnt leaf litter and vegetation are common because of the low fire intensity used. Burning down to mineral soil is uncommon. The usual aim in a planned FRB is to burn only about 70% of the area. Vegetation along creek lines normally does not burn in a spring burn as the soil and litter is too damp. Thus there is a mosaic of unburnt vegetation of varying ages throughout a FRB, providing a variety of ecological niches for flora and fauna.

FRB is part of the fuel reduction program required for successful fire management of our forests. To be effective in restricting the spread of a wildfire out in the forest a burn needs to be quite large – at least 1000 ha and with a depth of at least 3 km. This depth is necessary to stop burning embers being thrown over the burn area and igniting unburnt forest beyond. Small burns are ineffective as they are simply bypassed by a wildfire or spot fires are thrown right over them.

If fuel can be kept to no more than about 8 tonnes per hectare in the jarrah forest the damage caused by any summer wildfire under severe conditions will be kept to acceptable levels and the forest and its biodiversity will suffer very little damage from such a wildfire. This equates to a burning cycle of 5-7 years in jarrah forest. If the fuel is left to accumulate to more than this then a wildfire is likely to develop into a crown fire and do terrible damage; killing trees and animals, removing all humus to mineral earth, and converting the forest floor to deep black ash. It will also cover the entire burn area, leaving no refugial areas for wildlife. When the rains come, even if that is weeks later, the ash is washed into watercourses and reduces the quality of water flowing to our metropolitan and irrigation supply dams.

The most recent examples of such bad fires in WA are the Mt Cooke fire of 2003, the Perth Hills fire of 2005, and the Kings Park fire and Bridgetown fire in 2009.  There have been many more such fires of which the Dwellingup fire of 1961 is the most notorious.

However, from 1961 to the 1990s there was no major damage to our forests in WA from wildfires. This was because of a successful and extensive FRB program carried out carefully under mild conditions each year using information based on over 400 scientifically conducted experimental fires. The average area treated in this way was about 300,000 hectares over that period. FRBs are normally conducted in temperatures less than 30 degrees Celsius, wind strengths less than 30 kilometres per hour and a relative humidity generally greater than 30%. 

This 35 year period from the 1960s to the 1990s is the most conclusive long term evidence anywhere in Australia, the United States or the Mediterranean forest areas, of the benefit of FRB to minimise damage to the forest ecosystem caused by wildfires that occur under severe summer conditions, without the burn itself harming the forest.

 4. Does Fuel Reduction Burning Prevent Bushfires?

Fuel reduction burning (FRB) is mild burning which leaves most of the tree crowns unscorched, unlike the forest after intense wild fire, where virtually all tree crowns are scorched or completely defoliated. This usually results from a crown fire, in which the fire front moves through the tree crowns as well as through ground vegetation and litter.

FRB does not necessarily reduce the number of fires in a season, but it will certainly reduce the number of fires that cause damage and greatly reduce the effort required to control a wildfire. There is clear evidence from 40 years of experience in WA that that FRB, done at sufficient intensity to reduce litter over 80% of the area at 5 to 7 year intervals [in jarrah forests] will minimise uncontrollable crown fires.

In WA a FRB program covered most of the forest area by mid 1960s. It was based on lessons learnt from the Dwellingup Fires in January 1961. The burning program proved an effective barrier to devastating crown fires up to about year 2000 after the program was allowed to fall behind.

It minimised damage during emergencies such as Cyclone Alby in 1978, which caused over 70 wildfires, and prevented a re-occurrence of uncontrollable headfire runs such as the Boorara Fire of 1968.

Since the FRB program has been allowed to fall behind in our forests, there have been crown fires in recent years at Mt Cooke, Pickering Brook, Dwellingup, (again!)  and at Bridgetown, a sure warning for the future if the full burning program is not restored.

If any further evidence is needed refer to the almost annual event of wildfire damage in the Eastern States also in California where a massive fire fighting force, backed up by numerous aircraft, has failed for decades to prevent considerable damage. Neither area has a sufficient FRB program.

The message is quite clear from practical experience in WA forests: suppression forces alone will fail unless fuel has been reduced, and the recent fall back in the burning program is dangerous to people, property and the SW forests.

Claims that regular fuel reduction burning will damage the forest are not supported by research!

For trees and understory shrubs the results of actual research in jarrah forests are:

Trees

Assessments in the large and very intense 1961 Dwellingup fire area showed 55% of large trees [over 0.9m girth] and 77% of smaller trees were killed in the crown fire area.

btown-fire.jpg

 Typical aftermath of a crown fire in jarrah forest

 For previously green burnt areas only 1% of large trees were killed, and 35% of small saplings[1]

Shrubs

Fuel reduction burning produced a greater variety of species in understorey shrubs [2]. Intense wildfire produced a significant change, mainly promoting the  regeneration of dense acacia thickets [3] which caused later fire suppression problems.

 wandooburn22.jpg

 A low intensity burn in wandoo forest

References

[1] . Peet, G.B. and Williamson A.J. (1968) Paper To 5th IFA Conference, Perth. An assessment of forest damage from the Dwellingup fire in WA .

[2] Peet, G.B. (1971) A study of scrub fuels in the jarrah forest of WA. Bulletin 80 Forests Department of WA

[3] Peet, G.B. and G. W. Van Didden. (1973) Fire effects on understorey shrubs. Research Paper No 8, Forests Department of WA

5. Wild Fire and Water Catchments

In recent years there have been a number of large wildfires on water supply catchments, both in Western Australia, in Victoria and in the Australian Capital Territory. The West Australian examples include the 2003 Mt Cook wildfire (Canning catchment), the 2005 Hills wildfire (Helena catchment) and the 2006 wildfire near Dwellingup (Waroona catchment).

In all cases the short-term result is a serious loss in water quality as the result of a massive increase in soil erosion. In the case of the Hills wildfire, which was located on both sides and adjacent to the reservoir, the Water Corporation was nearly forced to cease supplying water from Mundaring weir.

This loss of water quality may last 1-3 years, until the vegetation begins to recover and again bind the soil in place.

In addition to the loss of water quality there is a longer-term loss of stream biodiversity as most pools are at least partly filled with sand and silt. In low-energy streams, such as ours, this sediment will then clog the pools for years.

There is also a much longer-term loss in water yield, caused by the wildfire. As the burnt areas vigorously regenerate through seeds, tubers and coppice, their water use increases greatly. Less water is then available to streams and for water supply. This effect may start at around 10-12 years after the fire and can last for several decades (i.e. up to 50 years).

The Water Corporation is measuring this effect in the Hills fire area, but the data are only available since 2005, which is too soon to note an effect. However data available from the Eastern States suggests that the annual losses may be measured in the Billions of litres.

Rainfall in our catchments has decreased substantially since 1975. Streamflow into our water-supply dams has also decreased, from an average of 350 Billion litres each year, to about one-quarter of this value since the year 2000. Only some 6% of rainfall falling on a catchment area is captured in dams. With good management this can be substantially increased at little cost, with no adverse ecological impacts, and with significant future savings in wildfire suppression with its inherent damaging consequences.

Any long-term loss in yield must be of concern.

Whichever way you look at it, large wildfires in catchment areas are BAD NEWS.

  6. What Are the Alternatives to Fuel Reduction Burning?

Tall, dry grass fuels can result in a very rapid spread of a fire because oxygen is readily available to the fuel. Mowing or slashing can be very useful in reducing the fire intensity and rate of spread of fire in grass fuels because once slashed the grass lies close to the ground and oxygen is less available because of this. Slashing is best done before the grass cures as sparks from a slasher striking a rock have been known to start fires in dry grass. Slashing leaves the grass on the ground exposed to the elements where it tends to break down and becomes a lesser fire hazard.

Grazing by sheep and cattle can also be very effective in reducing grass fuel prior to the fire season. This requires sufficient stock numbers being confined to the areas where grass fuels need to be reduced Chemical herbicides are useful in controlling grass fuels and are commonly used by farmers to establish fuel free fire breaks along the perimeters of their properties or around farm buildings. Special sprays are also available that control exotic grasses but do not affect native species.

Some people have claimed that native animals foraging on the forest floor will cover leaves and hasten breakdown of forest fuels. Whilst this can occur where a large number of animals are confined by fencing to a small area there is no evidence that native animals have made any significant impact on fuel levels in the broad forest area.

Attempting to put out a large bushfire burning in heavy fuels under summer conditions is usually impossible. US Fire authorities who have far more water bombers, helitankers and fire equipment than any Australian fire agency fail year after year to control major fires until the weather changes. A similar situation has occurred in the Eastern States in recent years where fires over one million hectare in size have occurred.

Until a better alternative is found, fuel reduction burning is the only real option available to control the level of fuel build up in W.A forests. The method was used satisfactorily by the aborigines for probably 40,000 years before European settlement and also for a 35 year period from the 1960s to the mid 1990s by the Forests Department and later CALM to prevent major bushfires.

 7. Management Options for  Fire in South West Forests

 Experienced land and forest managers can identify three potential options for the minimisation of bushfire damage in south-western WA.

1. The Let-It-Burn Approach

This assumes nature knows best. Bushfires are left to burn to their heart?s content, to go out eventually if they run into last years fire, or to be extinguished at the onset of the rainy season or tackled at the edge of the bush if human assets are threatened. This approach is advocated by many environmentalists and academics. Unsurprisingly, these people mostly live well inside surburbia, are not threatened by fires, do not have to fight them and cannot be held legally accountable for the outcome of such a policy. No government can afford (officially) to adopt the let-burn approach. This is because

(i) fires burning out of heavy forest country can be unstoppable when they reach the edge of the bush; and

(ii) under Common Law an effort must always be made by the land owner or manager to suppress wildfires, because not to do so lays them open to legal action.

2. The All-out Suppression Approach.

This requires fires to be attacked immediately after detection, using the resources of an emergency service, or fire brigade. This approach originated in the cities of Europe in the Middle Ages, and was exemplified by the drama of the ringing alarm bells, galloping horse-drawn fire engines and magnificently uniformed and helmeted firefighters. The current image is equally theatrical, with water bombers and helitaks sweeping the smoky skies, convoys of tankers filing along country roads, and brilliantly uniformed Fire Chiefs being interviewed on television by breathless reporters.

The all-out suppression approach is appropriate in cities, where there are permanent firefighters on standby 24 hours a day who are able to get to any fire within minutes. In earlier days in rural Australia the suppression approach was implemented by volunteer brigades of farmers and bush workers, and was largely successful in well managed farmland and country towns.

In rural Australia today, even in forest country the all-out Suppression Approach has become the dominant philosophy. This is the approach most favoured by professional fire fighters and some environmentalists. 

This approach flies in the face of practical experience and bushfire science. The all-out suppression approach does not and cannot work in Australian bushland unless it is supplemented by other measures (discussed below). Fires on hot windy summer days in long unburnt bush simply cannot be put out by humans, no matter how many, how courageous and how hard they work and how good their technology. Even under relatively mild conditions, the intensity of fires burning in fuels over about 10 tonnes per hectare is too great to allow them to be attacked successfully.

This is a situation which was once well understood by Australian forest managers. Which is why in the 1950’s there was a general move to adopt a third approach –  the substitution of controlled mild fire for uncontrolled high intensity wildfire, known these days as the fuel reduction burning approach.

3. The Fuel Reduction Burning Approach. 

This recognises two simple facts: Firstly, that bushfires cannot be prevented  even if we eliminated all mankind from the bush, there would still be lightning strikes. And secondly, periodic mild, patchy fires prevent the build-up of heavy fuels, so that when a fire does start it is easier and safer to suppress, does less damage, and costs less. A regime of fuel reduction burning also produces a healthier and more vigorous forest and is better for biodiversity. This approach was applied rigorously in many Australian forests for nearly 30 years, with tremendous success.

The fuel reduction burning approach calls for a well planned and professionally conducted program of burning. It is not a scorched earth approach or relentless firebombing as environmentalists like to depict. It involves mild trickling fires that burn quietly through the understorey, burning away dry leaves and twigs, so that when a real fire comes in mid-summer, there is less fuel to burn.

The fuel reduction burning approach does not mean that there is no need for fire suppression forces. Fuel reduction burning does not prevent fires starting! What is does do is make a subsequent fire less intense, easier to suppress and safer for firefighters.

The Bush Fire Front recommends that jarrah bushland in the southwest of WA should be mildly burned to reduce bushfire fuels about every 6-8 years, karri forests about every 9-10 years and wandoo forests every 4-5 years. This regime posts no threat to the ecosystems, but will minimise the risks of high intensitykiller“ bush fires.


 8. The Critical Importance of Expertise and Experience in Fire Management

Knowledge and experience in forest fire management is something that takes many years for people to attain. Fire behaviour is complex and the theory needs to be understood but also observed and tested in real burning and fire suppression situations to allow a person to learn and gain confidence.

Carrying out burning under mild conditions with experienced members of a burning crew is an essential prerequisite to understand fire behaviour at the low end of the scale, but also to be aware of the hazards involved and the safety measures that need to be observed.

Similarly, when actually fighting wild fires, people need to be allocated a minor role at first and under the eye of someone with proven ability. It is generally accepted that a person needs to have 15 or more years of practical experience in fire fighting to become a “fire boss’, i.e. the person in charge of the resources and fire-fighters in the field.

Because of the years involved in developing people for the roles they can be called upon to play in either fuel reduction burning or fire suppression, time needs to be set aside for training and the training planned for and recorded so that it is clear before each fire season the level of competencies in fire management each individual has reached. Similarly, as people age they need to be assessed and possibly retired from some roles for their own safety.

The decision to carry out a burn or assume control of a major fire suppression task requires a certain amount of courage. The person needs to decisive but to base decisions on the best information available on weather forecasts, intelligence reports but also on good judgement. The safety of fire fighters under his control is paramount.

Over the years there have been some tragedies in Australia where people with little practical experience in fire management have attempted to carry out a burn or suppress a fire in forest conditions. This has been most unfortunate and has sometimes led the agency involved to abandon fuel reduction burning as a means of reducing fuels and reducing the intensity of bush fires.

In Western Australia three men perished when fighting a fire in heavy fuels near Nannup in the late 1950s. Fire behaviour was much less understood in the ‘50s than it is today but it highlighted the dangers firefighters face when attempting suppression of fires in heavy fuels. Not only are these fires more intense, but also because the heavy fuel magnifies any sudden changes in wind direction.

The former Forests Department of WA led the field in Australia in fire management training and then trusting these people to carry out fuel reduction burns and lead the attack in fire suppression. Prescriptions were prepared for each proposed burn, based on extensive research, and the results from each burn were carefully assessed and mapped.

This is the right approach for an agency involved in forest fire management to take, i.e. do the research, train staff to translate the research results into field practice and then monitor the outcomes, adapting procedures as necessary.