Biodiversity publications archive

Biodiversity and Fire: The effects and effectiveness of fire management

Proceedings of the conference held 8-9 October 1994, Footscray, Melbourne
Biodiversity Series, Paper No. 8

Biodiversity Unit
Department of the Environment, Sport and Territories, 1996

19. Is fire management effective?

Charles Meredith
Biosis Research Pty. Ltd.

19.1 Abstract

Almost every action of government is now subject to intense economic scrutiny and, where actions are not seen as cost-effective, they are likely to be reduced or modified. Despite this, the costs and benefits of the management of forest fires have received relatively little attention. There is remarkably little information to indicate the effectiveness of many fire management practices, let alone whether they have a positive cost-benefit ratio. The existing situation is reviewed and a series of questions posed. If the debate about appropriate structures for forest management and about the practicality and costs of conservation reserves versus harvested forests is to reach any conclusions, answers will be needed for these questions.

Key words: fire management, effectiveness, prescribed burning, fire prevention, Victoria.

19.2 Introduction

I undertook a review of fire management in Victoria for the then Conservation Council of Victoria in 1988 (Meredith 1988). That review questioned a number of the assumptions concerning the effectiveness of some accepted fire prevention practices; it also noted the lack of evidence for the value of prescribed burning except under certain relatively narrow conditions – criteria that are not met for most prescribed burns in south east Australia. Since then, some of the questions raised have been taken on board by fire managers and have resulted in changes to fire management practices. This paper aims to review the current assumptions under which managers undertake prescribed burning and emphasise a few more issues which justify further analysis.

19.3 Review and discussion

19.3.1 Prescribed burning and associated assumptions

The reasoning behind prescribed burning can be summarised as:

low intensity planned fires will reduce the likelihood of ignition of wildfires and will reduce the intensity of those that do start to controllable levels.

This argument brings with it a range of assumptions:

  1. that the prescribed burns are effective for some years;
  2. that the desired frequency and coverage of burning will be achieved;
  3. that the environment is relatively uniform in space and time;
  4. that other aspects of fire prevention are of minor value.

Each of these assumptions is discussed below.

1. That the prescribed burns are effective for some years

Prescribed burning is the use of planned fire under relatively mild weather conditions to reduce fuel loads, so that unplanned fires are less likely to occur or will burn at controllable intensities. It was developed for Australian conditions in Western Australia on the basis of a small number of experimental burns and is now widely used in the forests in the south-west of that State. Other states, including Victoria, quickly adopted the technique for use in their forests. Its use in Western Australia appears to have reduced the incidence of very high intensity fires, although no adequate assessment of its success there has been undertaken. The one assessment that has been made showed that it was effective in helping control fires for three years after a burn (Underwood et al. 1985). It may be effective for longer than this, but the investigation by Underwood et al. (1985), which is lacking in statistical analysis, does not show this.

The apparent reduction in severe fires achieved in Western Australia is not mirrored in Victoria or elsewhere. The reasons for this appear to relate to the significant differences between the Western Australian forest environment and the forests of eastern Australia (Gill, M., CSIRO, 1994 pers comm, Hoare, J. CSIRO, 1994 pers comm, Tolhurst K., DCNR, 1994 pers comm). The Western Australian forests represent one of the best environments in the world for prescribed burning. Their total areas is relatively small (2 million hectares vs 7 million hectares in Victoria). Nearly all of it is dry enough for prescribed burning, while large proportions of eastern Australian forests are too wet for prescribed burning. This means that a much greater coverage is possible in Western Australia, where 16 per cent of their forest is burnt every year as against three per cent in Victoria (Tolhurst 1994 pers comm). Western Australian forests occur in areas of mainly gentle topography and are relatively uniform so that broadscale burns achieve high coverage; but eastern Australian forests are often in areas of dissected terrain and are a mosaic of wet and dry environments leading to very patchy burns. Finally, the weather patterns in Western Australia are much more predictable, allowing prescribed burning to be undertaken on more days per year and with more control. Despite this, as noted above, there is no statistically verified evidence that prescribed burning is effective against major fires for more than four years after a burn, even in Western Australia.

Few assessments of the effectiveness of prescribed burning have been undertaken in Australia and the existing reviews (e.g. Underwood et al. 1985; Rawson et al. 1985; Johnston et al. 1983) are largely subjective. This lack of adequate statistical analysis is also true of the larger numbers of analyses of individual fires; numerical analysis is generally absent or, if present, not statistically tested. The results of these few assessments and the subjective impressions of many observers strongly suggest that prescribed burning is effective against even severe fires for about three years after the burn. The data and theory of fuel dynamics are in accord with this. Due to the rapid rate of increase in litter loads after burning, relatively high levels are usually present by three-to-four years post-burn and from this time on fires occurring under conditions of high fire danger are going to present difficulties in control. For fires on less severe days, prescribed burning is likely to aid suppression for longer than three years. However, it is the fires under severe conditions that cause by far the most loss of life and property, as well as environmental damage, and perhaps it is their control that is one yardstick that fire management should be measured against.

2. That the desired frequency and coverage will be achieved

Fire managers commonly, when discussing broad-scale prescribed burning, complain that it is very difficult to achieve the desired frequency and level of coverage. It is also frequently argued that the effectiveness of prescribed burning could be improved by more frequent and less patchy burns (e.g. Rawson et al. 1985). This is undoubtedly true in theory, but in practice it is questionable as to whether this can be achieved.

In the current and foreseeable future economic climate, there will not be significantly more money for more staff or better equipment to improve the effectiveness of broad-scale prescribed burning. Even if more resources were provided, some aspects probably could not be greatly improved upon, as they are more strongly affected by environmental variability than by technical aspects of burning.

By contrast, frequent localised burning, especially to protect specific sites, is very effective. Managers are able to maintain desired burning frequencies more easily and the small size of the areas burnt means that coverage can be very high, with few or no unburnt areas remaining.

3. That the environment is relatively uniform

Environmental variability over time is a major factor in determining the success of fire management, especially broad-scale prescribed burning; yet the structure of forest management agencies, along with cost factors, makes it very difficult for managers to respond to natural environmental variability.

Environmental variability in space is equally important. Different vegetation types have different fuel dynamics, different fuel distributions, different microclimates, and so on. While all fire managers recognise that these variables are important in fire management, there is, an assumption by many that they can be overcome by technical means (as noted in the previous section); thus the fire environment is treated as though it is uniform as a planning and management convenience. This approach leads inevitably to poor planning and management decisions; it also reduces the potential effectiveness of the prescribed burns. It is surely better to explicitly recognise the limitations of the technique and to plan and manage accordingly.

4. That other aspects of fire prevention are of minor value

There is a strongly held view amongst fire managers that fuel levels are the only factor feasible to manage; this is a narrow view that unreasonably discounts the possibility for managing other aspects. For instance, there would seem in fact to be considerable scope for managing ignition sources by altering human behaviour through education and other programs.

As an example, our knowledge of ignition sources in Victoria is quite good, due largely to the tabulation of statistics by Rawson and Rees (1982), who summarise the data from 4196 fires occurring in the nine years 1972/73 to 1980/81 and those of Rees (1984) for the period 1974/75 to 1983/84.

From the results of Rawson and Rees – those of Rees (1984) are similar – it is clear that people cause most fires (62.2 per cent), with lightning the next most frequent cause (23.9 per cent). Of human-caused fires, the most common causes were escapes and relights from burning off and prescribed burning (18.2 per cent of the total), arson (17.7 per cent), campfires and barbecues (8.1 per cent) and cigarettes and matches (6.9 per cent). Fires due directly to forest management practices (other than prescribed burning) or timber harvesting constitute six to ten per cent of the total (it is hard to determine this exactly from the categories listed), while farm-related causes amount to 11.3 per cent, recreationists cause ten per cent, and local residents (excluding farmers and employees in local industries) cause 6.9 per cent of fires. If farmers and local employees are included, local residents caused 25.7 per cent of fires. Of the recreationists, vehicle-based tourists and picnickers cause 9.7 per cent of all fires, and bushwalkers 0.3 per cent.

The percentages are significantly different, however, when viewed from the point of view of the area burnt by fires caused by different ignition sources. Although constituting one third of all ignitions, lightning fires burn 60.3 per cent of the total area. Escapes, relights from burning off and prescribed burning amount to 20.3 per cent of the total area burnt; arson fires add a further 10.6 per cent. All other causes combined amount to only 8.8 per cent.

What is clear is that people cause about two-thirds of fires and thus constitute an ignition source that is, at least potentially, able to be reduced in frequency.

Looking now at Rees's (1984) statistics on forest fires, there are a number of interesting points relating to National Parks. Five per cent of forest fires start in National Parks, burning 4.3 per cent of the total area of forest burnt in the state. This is substantially lower than the 20 per cent of public lands that National Parks and reserves represent. State Forest comprises about 53 per cent of Victorian public land; 56 per cent of all forest fires originate in State Forest, burning 88 per cent of the total area of forest fires. Thus, in terms of potential risk of ignition, the risk is more than four times greater in State Forest than in National Parks or other reserves; in terms of area burnt, State Forests are almost eight times more dangerous. These findings conflict strongly with the commonly held belief that parks and reserves create fire risks.

Rees (1984) also provides statistics on causes of fires in different land tenures. Lightning fires are equally frequent in both National Parks and in State Forest. With the exception of arson, most other ignition causes are less frequent in National Parks, with a few of the minor ones being similar in both land tenures. Arson is twice as frequent in National Parks, as in state forest.

These simple statistics clearly have significant implications for the management of fire risk and it is surprising that so little has been done in this area.

19.3.2 Assets at risks

The degree of risk associated with fires in particular areas is a critical determinant of both the type and level of fire management needed. Take a single environment, a wet sclerophyll messmate (E. obliqua) forest. If the forest is in a bushland suburb, it will contain people and buildings. These represent a very high fire risk in this environment, dictating management that places a high emphasis on safeguarding life and property. The same forest in a large wilderness area represents a fire environment containing no major risk factors relating to life or property; although there is an acknowledged risk of ecological damage if fires are too frequent. If the wilderness area was reclassified for timber production, then the trees become a resource (asset) and the risk due to fire increases.

Timber production, plantations

In terms of risk management, many of the risk factors associated with forest fires relate to timber production. The fact that unburnt trees are a resource for timber production which is damaged by fire means that fire constitutes much more of a threat in forests utilised for timber than in forests not so used. The network of roads required both aids rapid fire suppression and provides access for more sources of ignition (campers, arsonists, etc). Management activities associated with timber production can cause fires: chainsaw sparks, vehicle accidents, escapes from slash burns, etc.

Large areas of dense young regrowth that can be present in intensively logged areas present special problems for fire management. They are often highly flammable with high litter loads and a low, continuous canopy of eucalypts. They are difficult to fuel reduce, especially as regrowth stands are often susceptible to fire damage, and are dangerous areas in which to have to fight fires, because they often contain considerable amounts of large fallen timber (slash). All these factors need to be counted as costs that timber production impose on fire management.

Pine plantations are highly flammable and, as pines are sensitive to high-intensity fire, a burnt pine plantation represents a considerable economic loss. The main effect of pine plantations on fire management that is relevant to environmental factors is on the management of surrounding or nearby native forest. Pine plantations represent a high fire risk and thus increase pressure for prescribed burns, roading and other fire protection measures in surrounding areas. These factors need to be taken into account when planning pine plantations.

Urban/rural areas

Urban/rural areas are those areas where moderate to high densities of buildings are sited in bush or rural settings. Such areas constitute very high fire risks. Most deaths and injuries due to bushfires occur in urban/rural areas, along with a very high proportion of property losses. Ignition sources abound, including a high frequency of arson. Broad-scale prescribed burning is generally not possible due to the high potential for damaging property even with a planned fire; the high proportion of private land can also make co-ordinated prescribed burns difficult. Buildings are seldom designed to be resistant to fire and many are highly flammable. Many people choose to live in these areas for environmental reasons and see conflicts between some methods of fire protection and the aesthetics of their environment.

Fire management is risk management, and if the potential risks are greatly increased then both the need for management and the difficulties of management are concomitantly increased. It is hard to imagine a more effective way to increase risk than by placing high numbers of people and densely developed properties in the midst of an already fire-prone environment. Thus it is clear that there is a spectrum of ways of coping with such a situation; ranging from accepting and living with a very high risk, to instituting stringent planning controls and highly intensive fire management.

In summary, the placing of houses in flammable bushland increases the risk factor associated with fire to such an extent that the need for trade-offs between fire protection and ecological management is greatly increased. The extent of the trade-off is dependent on the degree of risk that the community is prepared to accept. It needs to be stressed that fire protection works can be done in ways that minimise conflicts with environmental values. This may be costly or require considerable volunteer labour, and should be counted among the costs of rural development.

19.3.3 Costs and benefits


The cost of bushfires in Victoria is measured in millions of dollars annually. According to Loane and Gould (1985), bushfire losses in Victoria amount to $25 million (in 1983 dollar terms) per annum, on a long-term average basis. Losses are heavily concentrated in the occasional severe seasons; suppression costs average $8 million per annum. Loane and Gould (1985) give no figure for fire protection costs but Johnston et al. (1983) indicate that the Victorian Forests Commission fire protection budget in 1981-82 was $2.5 million. To this needs to be added the costs of fire protection work done by the Country Fire Authority and by public bodies such as V/Line. On these estimates, the average annual cost of bushfires in Victoria would be in the order of $35 million (1983 dollars).

Loane and Gould (1985) also found that, in most fires, suppression costs exceed losses and, on average, 85 per cent of the total losses due to fire are caused by less than one fire per year out of an annual total of around a 1,000 fires. Fire damages trees even though it seldom kills them, and this damage (fire defect) lowers the value of the timber, usually by between $10-40/ha, with much greater losses in the more productive forests; it should be emphasised that the above figures relate to unplanned fires.

Despite the large amounts of money involved, little is known about the economics of fire. Aside from Loane and Gould (1985), the other major study is that of Healey et al. (1985) which dealt with the economic effects of the Ash Wednesday fires in South Australia. Those fires caused output losses of $34.8 million (including flow-on effects, but excluding the costs of human suffering and the costs of asset replacement) but, somewhat perversely, stimulated the economy by $164 million. A variety of analyses in Healey et al. (1985) pointed up important equity issues involved in bushfire insurance and compensation.

Prescribed burning

Amazingly, it seems that no publicly-available cost-benefit study of prescribed burning or other fire protection works has even been done in Australia. In a time when economics rules all, and governments at all levels are happy to close down whole industries if analysis shows them not to be economically viable, fire management seems remarkably free of such constraints.

At the same time, a new question has been raised by those who are against further parks and reserves: who will pay for the management costs, particularly fire management, if we take forestry and forest managers out of the system?

The idea that forest management is more expensive or difficult in parks than it is outside them is incredible. On the existing statistics, parks are already four to eight times more effective at reducing fire risk and that's pretty cost-effective.

A proper analysis of the cost-effectiveness of prescribed burning would need to take into account not only factors directly associated with prescribed burning (direct costs, effects on forest productivity, water supply, soils, ecology, etc), but also a broader analysis of the risk environment in which it occurs.

19.4 References

Healey, D.T., Jarrett, F.G. & McKay, J.M. 1985, The Economics of Bushfires: the South Australian Experience. Oxford University Press, Melbourne.

Johnston, J.B., McKittick, D.J., Flinn, D.W. & Brown, H.G. 1983, Fire Protection and Fuel-Reduction Burning in Victoria. Office of the Minister of Forests, Melbourne.

Loane, I.T. & Gould, J.S. 1985, 'Aerial suppression of bushfires. Cost-benefit study for Victoria', National Bush Fire Research Unit CSIRO, Canberra.

Meredith, C.W. 1988, 'Fire in the Victorian environment – A Discussion Paper', CCV, Melbourne.

Rawson, R., Billing, P. & Rees, B. 1985, 'Effectiveness of fuel-reduction burning', DCFL Fire Protection Branch, Report 25.

Rawson, R. & Rees, B. 1982, 'A summary of forest fire statistics, 1972-73 to 1980-81', Forests Commission of Victoria Fire Research Branch Report 12.

Rees, B. 1984, 'Forest Fire Statistics, 1974-75 to 1983-84', Department of Conservation, Forests & Lands Fire Protection Branch Report 22.

Underwood, R.J., Sneeuwjagt, R.J. & Styles, H.G. 1985, 'The contribution of prescribed burning to forest fire control in Western Australia: case studies', in Fire Ecology and Management in Western Australian Ecosystems, Western Australian Institute of Technology, Environmental Studies Group Report No. 14, pp. 153-170.