Bush Fire Front

Causes of Bushfires

The main causes of bushfires in Western Australia are:

• Accidents, such as vehicle fires.
• Human carelessness, for example from cigarette butts or escapes from campfires.
• Arson.
• Lightning.

It is not possible to completely eradicate bushfires. Even if there were no accidents, acts of human carelessness or incendiarism, bushfires would still be started by lightning, as they were for many millennia before the arrival of humans on the Australian continent. However, we can minimize the number of human-caused fire ignitions by public awareness programs, and much effort has been devoted to this over many years. Despite this effort, we still have large numbers of such ignitions each fire season.  

    Lightning - a frequent cause of forest fires.  

The State Government must have a clear bushfire policy, stating the priorities for fire protection, and setting out who is responsible for achieving them. We understand that current policies are under review. It is essential that any changes resulting from the review provide real improvement in forest fire management, and in a way that is cost-effective.
There must be a strong program of fire prevention and minimising the impact of bushfires, principally by reducing fuels in forests. This program was set up years ago, but has been let slip and is now dangerously out of date.
There must be good access to forest areas to enable rapid attack on fire outbreaks. There is concern that recent and proposed expansion of wilderness areas has resulted in pressure for extensive closure of existing access tracks. This will make it more difficult to carry out prescribed burning as well as slow down the initial attack on wildfires.
There must be an organisation set up to tackle fires, comprising well-equipped and adequate numbers of well-trained, experienced, firefighters The government has done some good work in this area, through the provision of new equipment to brigades, but the best firefighters in the world will be defeated by hot fires in heavy fuels.

The Importance of Fuel Reduction Burning in Forests

Prescribed burning for forest fuel reduction offers the only practical way of reducing forest fuels. Other approaches have been suggested, such as mechanically removing the litter and undergrowth, but have not proved to be practical or cost-effective. 

Fire in heavy litter like this is impossible to control in severe fire weather

Burning has a number of incidental benefits to the forest ecosystem. Nutrients locked up in slowly decaying woody material are released and re-enter the forest nutrient recycling system. While some nitrogen is lost to the atmosphere, it is counterbalanced, in nature’s way, by the stimulation of regeneration of leguminous understorey plants. Indeed, it has been shown that some plant species depend on the smoke from fires to stimulate germination.    A crucial issue is the level of prescribed burning required to achieve the level of protection that has been achieved over the period 1963-2000. Over that period the annual area of prescribed burning has fluctuated in response to seasonal weather conditions, but has averaged about 300,000 ha year of the total 2,500,000 ha of the forested zone. In this context, the forested zone includes other ecosystems within the forest envelope, such as rocky outcrops, swamps and flats.   In the jarrah forest types, the burning rotation varied from 5-7 years, according to site, but was only about three years in the vicinity of towns, valuable assets like plantations and important infrastructure. In karri forest types, the rotation was necessarily longer, 8-12 years, with even-aged karri regeneration protected from fire for up to 30 years. In the jarrah forest, changes in the silvicultural system associated with procedures to restrict the spread of jarrah dieback disease led to more concentrated timber harvesting, so that it also became necessary to protect jarrah regrowth from fire for up to 20 years. These factors greatly complicate the burn planning process.  Over the last 10 years the level of prescribed burning by CALM has declined drastically and average fuel loads have increased markedly. A large backlog of burns has built up in that time. Current CALM policy is that an annual area of prescribed burning of 200,000 ha year is sufficient to provide adequate protection against large wildfires. There is no scientific basis for this policy. It is not supported by the experience of the last 40 years, which indicates that the annual prescribed burning area should be 300,000 ha.      The graph above shows how the annual area burned by wildfire or by prescribed burns has varies since 1951. It can be seen that while the prescribed burn area was around 300,000 ha a year, the area of wildfire was very low. But when the area began to fall away after the formation of CALM in 1983, the area of wildfire started to climb, after a short lag period.   On CALM’s own data, over 60% of the forest area will contain fuel loads at which direct attack on a wildfire will fail under even moderately severe conditions. The Muller report of 2001 clearly outlines this problem and also highlights the longer response times to get to a fire outbreak, due partly to downgrading of some district offices, and partly to closure of forest access roads. In this context, the planned closure of even more roads in areas proposed to become wilderness is of great concern. Forest with high fuel loads raises the important issue of safety of firefighters. The higher the fuel load the greater the fire intensity and the more erratic fire behaviour becomes. Fire fighting is inherently a dangerous activity at the best of times, but we are significantly raising the risk to this vital component of the fire management system as fuel loads increase. Already, there are reports of volunteer bush fire brigades expressing unwillingness to assist CALM in fighting fires in some areas due to the perceived high risk involved.    It is claimed by some that the previous approach to forest fire management, based on regular prescribed burning, has adverse effects on biodiversity. Such claims do not recognize the diversity of fire intensity that occurs in a prescribed burn, nor the fact that about 30% of the area remains unburnt. It is notable that one rarely sees a person engaged in, or experienced in, on-ground fore management making such a claim. The requirement of some plant species for a certain period of time before they can set viable seed is often advanced as a reason why there should be no burning at all, or at least much longer burn rotations. While this may be a problem in theory, no one has ever been able to document any practical adverse impacts of this kind. In fact, the very comprehensive studies undertaken in association with the ill-fated Regional Forest Agreement Process indicated that no known component of forest biodiversity had been lost from Western Australian forests. At the present time there is no scientific evidence that the previous prescribed burning program has had any adverse effect on biodiversity.       

What happens in a fuel reduction burn?

It is important to understand that when an area has had its understorey fuel reduced by a prescribed burn, it does not become a firebreak, in the sense that it will stop a running fire, unless the burn has been quite intense, as is often the case with an autumn season burn. The crucial change, with respect to fire management, is that when the fuel is do reduced, fire behaviour is less intense and it is possible to attack a fire front under even quite severe weather conditions. For example, in jarrah forest fuels, once the litter has accumulated beyond about five years, frontal attack will fail, but can succeed when the litter is less than five years old. 

Except for a special type of prescribed burn, one required to be intense to create ashbeds for karri regeneration, prescribed burns are not intended to remove all litter and understorey vegetation. The usual objective, in a burn intended to reduce forest fuel, is to have the burn extend over only about 70% of the land area. This means that the more moist sites within the burn envelope will not burn, and these are usually the more important sites for native fauna refuge and feeding. There will be additional unburnt patches scattered through the burn area, and these will serve as centres for recolonisation by insects and small fauna, in the constant ebb and flow of organisms that characterizes natural ecosystems.    Furthermore, in a high proportion of spring burns, the fire does not remove the lowest litter layer, that which is already partly decomposed. Fire intensity, although low, varies considerably throughout a prescribed burn, due to variations in fuel loading, and this provides a diversity of impacts on vegetation that promotes biological diversity. For example, patches of land that did not ignite in one burn, may well ignite in the next burn, 5 years or so later, and because they carry twice the fuel load, will burn at higher intensity, adding to the diversity of fire impacts in the burn.      The season of burning also has a significant impact on fire intensity. Most prescribed burns take place in the spring period, from September to November (December in the south), because that is the time of year when the fuel drying rate, a critical factor in burn planning, is most regular, and weather conditions are most favourable. Autumn burns generally have higher fire intensity and it is more difficult to restrict the fire to the planned 70% areal coverage. Scorch height is always greater in autumn burns. The weather in autumn is more unpredictable. Early rains that produce good conditions for prescribed burning may be followed by dangerous fire weather when a burn may escape and cause severe damage. Conversely, in some years, no autumn burning is possible as the rains start and continue in such as way as to prevent the necessary litter drying process.     The planning process has, for many years, attempted to program burns on a particular area so that two or three spring burns are followed by an autumn burn, as a precautionary measure to avoid any unforeseen adverse biological impacts. However, this is not always possible. These days, it may take up to three years to complete all the processes involved in planning a prescribed burn. The list of instructions used by DEC for planning a burn runs to over 70 pages. It is extremely complex and comprehensive, covering such areas as: 

• A technical burn description.
• Background information on the particular area.
• Checklists for the day of the burn, action plan and maps.
• Procedure for post-burn assessment.
• Lists of notifications to be sent in advance of the burn.
• Post burn evaluation and report.

The Scientific Background

The fire research program in Western Australia commenced in 1961 has continued to the present day, albeit at a reduced level in the last 15-20 years. It has included a variety of forest types and covered many aspects of fire behaviour, fire ecology, nutrient recycling and fire ignition techniques. Some has been carried out in collaboration with CSIRO. Overall, it has produced a vast fund of information and understanding of fire management issues specific to Western Australian conditions. 

 Some research on fire impacts had been carried out earlier, focusing on possible effects on nutrient recycling. Initially, the new 1961 fire research program was oriented to providing answers to the pressing operational problems of the time – how to place the field prescribed burning program on a scientific basis, where the hit and miss approach of the past could be replaced by systematic field procedures and where outcomes of burns could be predicted with confidence. This required much basic work on litter drying rates and measuring the intensity and rate of spread of experimental fires under a range of fuel and weather conditions. Over 600 experimental fires were conducted in the jarrah and karri forest types, so that there is a very sound scientific basis for the practice of prescribed burning in Western Australian forests.

A considerable amount of work was concerned with the development of methods for increasing the rate of progress of the prescribed burning program. In cooperation with CSIRO, this led to the development of the unique aerial ignition system. Aerial burning enabled much larger areas to be burned under ideal weather conditions, improving the control of the burning process as well as reducing the cost. 

Later, attention turned to the ecological impacts of fire on flora and fauna. Long term study sites comparing flora impacts of various degrees of fire intensity and season of burn with long unburnt areas were set up. Radio tracking was employed to study the behaviour of fauna during prescribed burns (see Christensen, 1980). Because the biological diversity of forested ecosystems is complex, fire effects are similarly complex. A good summary of the current state of knowledge is given by Friend and Wayne (2003). 

Since about 1980, additional fire ecology research has been carried out in academia, which has contributed to the large amount of information we now have. However, while there is always a great deal more detail we wish to know, we do have sufficient information to be sure that it is essential that prescribed burning occurs in forested ecosystems to maintain biodiversity. The main issues currently debated are concerned with how to integrate the needs of different components of the biota. Trying to eliminate fire from the forest is not a practical option, and has adverse effects on biodiversity, while large high intensity bushfires have a disastrous impact on biodiversity and really have the potential to cause a faunal species to become extinct. 

Environmental Impacts on Flora and Fauna

Carefully planned prescribed burns can be used to create the habitats required by some animal species, or to protect those habitats from wildfire. A good example of the latter is the swampy vegetation required by the mainland quokka. In a spring burn, the dense swamp vegetation will not burn, but the surrounding higher and drier forest areas will burn, thus creating a firebreak around the quokka refuge areas. 

The behaviour of forest animals during prescribed burns has been monitored using radio location equipment. It has been found that they are not particularly concerned by low intensity prescribed burns, and can easily evade the flames and move off to unburnt areas. In contrast, high intensity wildfires are commonly observed to incinerate many native animals. 

Ground dwelling animals, such as kangaroos and wallabies, move into freshly burned areas within days of a burn, as many native plants rapidly produce new shoots that are keenly sought after as fodder. In fact, if only small areas are burnt at one time, the grazing pressure can be so intense as to cause excessive damage to the regrowth. 

Many other ground dwelling animals, such as reptiles, take shelter under logs or in holes, so are protected from the heat, unless fire intensity is too high (as is found in a wildfire). Birds are generally also not particularly concerned by low intensity prescribed burns. In the main forest zone there are no ground-nesting species that would lose nests in fire and those that nest in understorey shrubs have generally completed their breeding by the time that vegetation type will carry a burn. However, on some occasions there will be some losses of some species of fauna. This is not necessarily a serious problem, except in the case of rare and endangered species, as population numbers can be quickly restored from adjacent populations and from unburnt patches. Such ebbs and flows of populations are common in nature and represent one way of ensuring widespread gene flows. Rare species receive special consideration in the planning of the DEC burning program.     

 Forest Fuels and Animals

A question that is sometimes asked is: Is it true that fuel only accumulates in forests these days because of the loss of small mammals that used to eat it or dig it into the soil?

This is an interesting question, as it has an appealing ‘balance of nature’ feel about it and it seems to offer a neat solution to the controversial question of the role of fire in our forest ecosystems. We instinctively feel therefore, that the answer to the question should be yes. Regrettably, the short answer, however, is no, returning the small animals to the forest is not the answer to the ’so called’ problem of fuel build up.

The idea appears to have arisen because of observations made by various people of native animals in natural bush enclosures. When animals are kept in a bush enclosure {a section of bushland fenced off, usually to keep out exotic predators} they tend to build up in numbers to unnaturally high populations that can cause unnatural effects. These effects are usually obvious to the naked eye and depending on the species and other factors they can include;

#  openness of the ground  layer - caused by trampling and compaction of the litter layer which also causes earlier breakdown of otherwise long persisting leaves and bark.

#  a high percentage of bare ground and disturbed soil - caused by excessive digging activity exposing the soil and also causing earlier breakdown of the litter layer by burying leaf litter.

#  openness of the undergrowth - caused by excessive grazing pressure on leaves of scrubs that under normal circumstances would be grazed only lightly or not at all.   

#  general openness of the area - caused by lack of regeneration of grasses, herbs and shrubs due to over-grazing by the animals.

The result - a general impression of a lack of build up of fuel on the woodland or forest floor. This impression can be very strong since the phenomenon is ‘observed with the observers own eyes’ and often also re-enforces previously held convictions with respect to fuel build up in our forests. The majority of Australians of European extraction have never been comfortable with the concept of fire, especially frequent fire, being a natural part of the Australian forest ecosystem.

The reality is that small animals were never present in numbers that would cause the observed effects over the general forest area. In the jarrah forest, we know this because in areas where animals still exist in high numbers, for example, some of the forest area to the east of Manjimup, fuels still accumulate at rates that have allowed several wildfires to occur over the last few decades. In the karri forest where the understorey is dense, fuel accumulates rapidly in spite of the fact that the pre-European fauna is still largely intact.  

In some open woodland communities where fuel accumulation is naturally slow and where mammal diversity was high small mammals would have had some effect on the rate of fuel accumulation. Also a few woodland species that occur naturally in high numbers in specific and restricted habitats, e.g., the tammar wallaby (Macropus eugenii), can have some effect on fuel accumulation rates.

The tammar wallaby reduces the fuel to a limited extent under the thickets in which it shelters, however, over the majority of the area that it inhabits, the tammar has limited impact on fuels. This observation is supported by the fact that wildfires in the Perup district, to the east of Manjimup, have been observed to burn out thickets with dense populations of tammar on at least two occasions over the last 30 years.

In conclusion, the effect of small mammals on fuel accumulation in forest areas is likely to have been insignificant and of little practical importance with respect to fire protection.      

The Smoke Issue

In the last 20 years, smoke management has become an important issue. Smoke from prescribed burning has drifted over the metropolitan area on a number of occasions and prompted public concern over air pollution. Despite careful planning to avoid this event, some smoke drift has occurred, mainly due to unforeseen wind changes. Strict guidelines have been evolved to minimize the risk of this occurring, but the downside of these guidelines is that it is now extremely difficult for DEC to carry out fuel reduction burns in the region immediately to the east of the city. As a consequence, fuel loads in that area have built up to dangerous levels. The Bushfire Front is certain a major disaster, on the scale of the 2003 Canberra fires, or even worse, could happen here.

The issue has reached a point where it has become a stark choice for city dwellers; either accept a certain level of smoke drift over the city during the prescribed burning season, or endure much heavier levels of smoke and the social and economic consequences of a major bushfire disaster.

Some have argued that smoke from the burns poses a threat to public health. This is highly debatable. It is a fact that air pollution monitored by the Department of Environmental Protection has shown that pollution as a result of smoke has exceeded target levels only for a few hours on one or two occasions each year over the past 10 years. While there may be some inconvenience to certain groups, such as asthma sufferers, they have the means to alleviate the discomfort and can avoid contact with smoke, if warnings are provided.

In May, 2003, the DEP released a report on a major study of air pollution in Perth in relation to public health (DEP Technical Series 114, Research on Health and Air Pollution in Perth: Morbidity and Mortality: A Case-Crossover Analysis 1992-1997). This report did not identify smoke from prescribed burning as a significant cause of air pollution in Perth. Rather, existing air pollution concerns centred around emissions from motor vehicles and industry. It is unfortunate that public concern about occasional instances of smoke from burns over Perth is stirred up by unbalanced media reporting. The common practice of only reporting one-sided comments from parties opposed to prescribed burning is not in the public interest.

Air pollution as a result of wildfires has also been studied in Sydney. According to the NSW Department of Health (HARP Newsletter No 2, December 1994) the January 1994 bushfires did not result in any significant increase in asthma hospital admissions at the time. The January 2005 Perth Hills bushfire which blanketed Perth with dense smoke for a whole day also did not cause an increase in hospital admissions because of asthma.

In a Nutshell:

The prescribed burning regime followed over the past 40 years or so in Western Australia has provided virtually complete protection against the sort of large forest wildfires that have been a feature of the Eastern States in recent years, even though severe summer conditions occurred during that 40 year period.

* This prescribed burning regime has not resulted in observed adverse impact on biodiversity, probably due to the inherent diversity of fire intensity within any fuel reduction burn. In fact it has avoided the large scale adverse impacts that are observed in large wildfires.

* Reducing the level of the prescribed burning program below that of the last 40 years, which gave this proven level of protection to life, property and biodiversity, risks catastrophic consequences on the scale seen in NSW and Victoria in 2003.

* Large high intensity wildfires have now begun to appear in WA forests (Cooke and Walpole fires in 2003, Perth Hills fire 2005, Dwellingup fire 2007), due to a reduced level of prescribed burning by DEC. The adverse impact of these wildfires on both biodiversity and community values are demonstrably infinitely greater than anything possible under the former prescribed burning regime.

* While the Bush Fire Front is strongly supportive of the fuel reduction burning program being carried out by DEC, we simply believe it is not large enough. We must restore the level of prescribed burning in WA forests to about 300,000 ha a year as soon as possible, in order to avoid large scale fire disasters.

Best Practice Forest Fire Management System for Western Australia

What do we mean by a Best Practice Forest Fire Management System? It is a package of policies and activities that:

* Delivers community protection from destructive bushfires.

* Minimises undesirable impacts on the environment and needless costs to the Government and the community.

* Maximises safety to firefighters.

* Is based on credible science.

* Has widespread political, community and media support.

Key points of a Best Practice System

1. Overarching legislation

2. A State Bushfire Policy

3. An intergovernmental agreement between the State and Commonwealth Governments

4. A State-level agreement between the forest management agency and other key agencies

5. A single land management organisation responsible for forest planning, forest management and forest fire management on forested crown lands.

6. Preparation of a Fire Management Plan by the responsible agency

7. Adequate funding for the responsible agency fire management operations

8. Independent monitoring and public reporting on outcomes on an annual basis.