The statement was adopted by the Australian Association of Rural Fire Authorities (AARFA) as a national policy on the issue of prescribed burning and smoke (at the 9th National AAFRA Conference held in Victor Harbor, South Australia, 12-13 May 1992):
For several million years fire has been an important environmental factor in the ecology of Australian vegetation communities. There have been wide fluctuations of climate and associated vegetation types – ranging from moist-temperate or tropical rainforests, to dry sclerophyll vegetation. During periods when dry sclerophyll vegetation has dominated, evidence from charcoal in sediments indicates the occurrence of periodic fires. Natural ecosystems are adapted to particular fire regimes. With the coming of the aborigines some 25,000 to 40,000 years ago, natural fire patterns changed. The aborigines were nomadic hunters and food gatherers and moved regularly about the countryside in small tribal or family groups. They often practiced “fire-stick farming” – the deliberate and systematic lighting of the vegetation in consecutive sections over a cycle of years – to facilitate hunting and food gathering. This extensive and frequent use of fire by aborigines led early explorers and pioneers to refer to Australia as the “Smoky Continent”.
When Europeans came to Australia the consequent changes in land use had an immediate effect on this fire pattern. In many parts of Australia the cessation of aboriginal annual or biennial burning was immediately followed by an increase in the height and density of both the understorey and overstorey vegetation, and a change in many fuel types from a grass dominated fuel to one dominated by litter and shrubs. As a result of this increase in fuel load, periodic fires lit naturally by lightning, or accidentally or deliberately for clearing, grazing or prospecting were intense and destructive. Land holders and forest managers learnt that periodic fuel reduction burning reduced the natural build-up of litter and made the control of wildfires easier, improved the safety of their community and protected their farms and forests.
Today landholders, fire brigades and Government agencies responsible for the management of public land use, prescribed fire for the protection of human life, private property and assets from wildfire; for habitat and ecological management; and for forest regeneration.
Smoke from vegetation fires is a product of a natural process and, in dry periods, a natural part of the atmospheric environment in the same way as is dust during droughts or sandstorms in the desert. The products of burning vegetation, whether by a wildfire or a prescribed fire, are mainly carbon dioxide and water with trace amounts of carbon monoxide, ozone and methane, and minute traces of nitrous oxides and a great variety of hydrocarbons in the form of gases, oils, tars or carbon based particulates (the latter of which are “recognised” as smoke). Smoke from wildfires is accepted by the community, however smoke from prescribed fires needs to be managed, in order to address community concerns, particularly reduced visibility, perceived health hazards and contribution to the greenhouse effect.
Smoke from an ex-perimental fire in Australia’s eucalypt forest: a source of controversial debate on air quality aspects of prescribed burning (Photo: C.S.I.R.O.).
This AARFA statement addresses the issue of prescribed burning and smoke, and recognises that:
Each year in Australia weather conditions occur under which, given sufficient fuel, wildfires can be impossible to control.
Under extreme conditions, uncontrolled wildfires have the potential to burn extensive areas, cause enormous damage to people, communities, property, private and public assets; crops and farmland; forests, fauna and vegetation communities; and catchment values, as well as generate enormous quantities of smoke.
The speed and intensity at which a wildfire burns is related to the quantity and arrangement of accumulated dry litter or other fast-burning fuels. In most ecosystems accumulated fuel loads can be safely and effectively reduced by prescribed burning.
Managers of public land and owners of private property have a statutory and/or duty of care responsibility to carry out appropriate works which reduce the occurrence and spread of wildfires, and protect life, assets and ecosystems.
There is conclusive evidence gathered throughout Australia to indicate that fuel reduced areas temper erratic wildfire behaviour, reduce the incidence and occurrence of spotting and provide a safe working place from which successful wildfire suppression action can be based.
In appropriate vegetation types prescribed burning is regarded as the most efficient, ecologically suitable and economic method of reducing fine fuel loads over large areas.
Public land managers and private property owners have a responsibility to ensure that prescribed burning is strategic, timely, appropriate and correctly applied
Fuel reduction by low intensity prescribed burning can be most safely carried out under stable atmospheric conditions. However these conditions provide an atmospheric “lid” over the fire, often resulting in smoke build-up at the time of or after the conduct of a burn.
Smoke particles absorb and scatter light thereby reducing the contrast between an object and its background, and affecting the human perception of colour. This reduced visibility may cause safety hazards at airports and along roads, and loss of aesthetic landscape values.
There is a perception in the community that prescribed burning smoke can cause a negative impact on quality of life issues. No conclusive evidence is available to support this contention, and there are no medically established standards which define concentrations of smoke or durations of exposure which may cause short- or long-term health effects.
Prescribed burning, and any associated smoke, is an infrequent occurrence of short duration. By contrast, industry and vehicles generate smoke and other chemical emissions daily, all year-round with significant negative effects on health.
Fire is a natural process in the carbon cycle. The carbon released through burning is taken up again in the process of plant growth and litter accumulation. The contribution of forest fires to the increase in atmospheric carbon dioxide concentration is ultimately related to any long-term change in standing biomass in the forest. Thus if mature forests attain their pre-fire or pre-harvesting biomass in subsequent rotations, then the contribution made to an increase in atmospheric concentration of greenhouse gases, and the greenhouse effect would be small.
Repeated high intensity wildfires can dramatically reduce the amount of biologically stored carbon (for example the degrading of tall forests to scrub or grasslands, and deep peats or organic soils burning under drought conditions) whereas low intensity prescribed burning only consumes the fine surface fuels, about a tenth of the biomass consumed by wildfires.
The key role of fuel reduction by low intensity prescribed burning is therefore to reduce the frequency and extent of summer wildfires, it also has the effect of preserving or increasing the total biomass in the forests, both important in maintaining balance within the carbon cycle.
In the light of the above statements, AARFA advocates that:
Wildfires and smoke be recognised as inevitable and natural parts of the Australian environment.
Low intensity prescribed burning be recognised as one of the most important tools available to land managers for protection from and the safe and effective control of wildfires.
In appropriate vegetation types, prescribed burning be recognised as an efficient, ecologically suitable and economic method of reducing fine fuel loads over large areas.
Public land managers and private property owners accept their responsibility to provide fire protection to the community and its assets and use prescribed burning as a tool to achieve this objective.
Research be carried out on smoke from prescribed burning to determine its “finger-print” and thereby its effect on urban atmospheric quality.
Computer modelling and back-tracking techniques be used to predict whether prescribed burning smoke will accumulate in and around major cities, airports, tourist and visitor points and other major smoke sensitive areas. These models be used to determine if burning at other times of the year, or other burning strategies will minimize the impact of smoke accumulations.
Co-operative interaction be developed and encouraged between appropriate fire and environment agencies regarding the ongoing collection and dissemination of information on the quality of life impacts of prescribed burning smoke.
Co-operative interaction be developed and encouraged between appropriate fire and environment agencies to establish realistic and measurable standards for and acceptable quantity of smoke in the atmosphere, so that land managers can undertake prescribed burning operations within those standards.
Co-operative arrangements be made with agencies such as the Bureau of Meteorology and the Environment Protection Authority in each state to assist public land managers and private property owners to achieve their statutory and/or duty of care responsibilities in an environmentally and socially acceptable manner.
Appropriate smoke management guidelines be developed and applied to the development of prescribed burning strategies.
From: John B.Barclay Executive Officer, Australian Association of Rural Fire Authorities Address: 7 Hyton Crescent AUS-Croydon, Victoria 3136