Fire is a very controversial factor in Australian terrestrial ecology. A lot of this controversy is based on the effects of fire on settlements close to flammable habitats and the potential for the loss of human life, resulting in calls for widespread fuel-reduction burning in and around settled areas. But there is also controversy over the use of prescribed burning on a landscape scale and the almost universal policy to suppress fires wherever and whenever they start, even well away from settlements.
Some argue that fire is a necessary ingredient for the health of many ecosystems in Australia. For thousands of years fire has played an important part in all of Australia’s ecosystems maintain biodiversity and ecological health.
This research paper focuses on these issues and examine how best to manage fire for ecosystem health in Australian biomes.
1. History of Fires in Australian Biomes
Fire regime is the central concept to understanding the ecological impacts of fire. Fire regime is a sum of such characteristics frequency, intensity, seasonality and type of fires.
Fire regimes on the Australian continent have varied over time.
The continent was wetter and covered by rainforests 45 million years ago, but as it moved northwards, due to the break-up of Gondwanaland, it dried out. As a result, extent and frequency of fires increased as in many areas vegetation changed to a sclerophyll-dominated flora (White 1998).
Australia’s indigenous occupation of, which started approximately 45-48 thousand years ago, altered the fire regime. , Although conclusion on its specific impacts is not conclusive yet, it is clear that Indigenous-inflicted burning depending on climate and vegetation varied with time and geography (e.g. Bowman et al. 2003). Climatic such as El-Niño would have, as they do now.
At the same time, fire regimes were affected by periodic climatic variations, which produced drier periods and recurrent large-scale fires were and wetter periods with relatively fewer fires. Moreover these variations interacted with anthropogenic fire regimes.
Next stage of fire regime evolution in Australia began with European settlements on the continent. These settlements altered prevailing fire regimes in number of ways. Fire frequencies were increased due to land clearing. At the same time their frequency was reduced by suppression in settled and adjacent areas. Furthermore, Indigenous people were drove away from their traditional habitats by European settlement in much of Australia and their way of life was changed due to interaction with Europeans, which profoundly altered fire regimes in Australia. For example, as the result of traditional burning practices breakdown in northern Australia, incidence of large-scale wildfires in late dry seasons significantly increased (Russell-Smith et al. 2003).
Comparatively recently, fire frequencies, intensities and seasons were significantly changed as a result of large-scale undertakings of modern Australian inhabitants on fuel reduction in forests, woodlands and heathlands. The following chart presents graphical example of high frequency of fires in Australia in recent years:
2. The Data Available on How Fire-Tolerant Ecosystems and Individual Species Respond to Fire
Frequency of fire historically depended on the types of the vegetation, however, it should be noted that without a strong interference from human, the intervals between fires may vary widely from the average. Fires in rainforests are absent or exceptionally infrequent (unless corresponding conditions occurred due to logging, cyclones, or frost). In wet sclerophyll forests fires are infrequent (in Mountain Ash fires in Victoria frequency is 37–75 years, 75–150 years for intense, tree-killing fires), but when they do occur they often have very high (McCarthy et al. 1999). Fires in temperate heathlands typically occur at intervals of between 7 and 30 years. At the same time in tropical savanna woodlands and grasslands fires on average may occur every other year. See details in the table below:
Table 1: Suggested fire intervals for vegetation types in Southeast Queensland
|Fire intervals in years
|Wet sclerophyll forest
|Inland (rocky) heathlands
|Paperbark (Melaleuca quinquenervia) woodlands
|Shrubby dry sclerophyll forest and woodlands
|Grassy dry sclerophyll forest and woodlands
Source: Fisk et al (2003, Table 7.5)
With respect to ecosystems, one of the major issue with fires is how they effect biodiversity. Fire regime can have various effects on biodiversity. Intensity and residence time of fire may affect both, the amount and proportion of species that survive a particular fire and regeneration processes. Many species have certain minimum interval between fires to regenerate after fire.
While death of individual organisms (both animals and plants) is an evident effect of fires, a number of indirect effects are more critical for the preservation of biodiversity in a given region.
Particular fire regimes may have significant variation of effects on different species, because of different characteristics or attributes of the latter. For flora, an important species attribute is the dependence of post-fire regeneration on seeds (such plants are classified as seeders) or ability to resprout after fire (resprouters). General scheme of regeneration of plants is presented in the chart below.
So called vital attributes, the responses of plants to disturbance, can be used to classify organisms. Although a number of long-standing schemes exist for classifying plants (Noble and Slatyer 1980, Noble and Gitay 1996), similar schemes are lacking for animals.
Vital attributes systems allow differentiating plants according to their sensitivity to recurrent disturbances such as fires (Noble and Slatyer 1980, Noble and Gitay 1996).
According to the finding of such approach, the most sensitive species with established individuals (adults and juveniles) prone to death by disturbance (i.e. have no capacity for vegetative recovery) and seed banks exhaustible by disturbance. These sensitive types of this exhibit high rates of mortality of individuals irrespective of fire intensity and have seed-banks with germination strongly triggered by fire. There are evidences that such species with high sensitivity to fire frequency represent a wide range of plant communities in Australia (e.g. Bradstock et al. 2002).
On the other hand, for some plants fire is an essential part of their reproduction and life cycle. Some of these plants require the heat of a fire to release their seeds; other require the smoke to germinate. For example, Banksia plant has seeds in tightly-closed capsules, which burst open and release winged seeds, which also take advantage from soil enriched by fertile ash from fire. Many other plants also take advantage of the fertile ash-covered soil and reduce competition for sun, water and nutrients. Therefore fires often trigger regeneration in such zones as Mediterranean bush.
For fauna besides fire mortality effects of fire lie in variations in vegetative cover. While some species require dense plant cover for shelter, others prefer by more open conditions resulting from fires. Among animals that are heavily affected by fire regimes are those who depend on seeds for food. Similarly, animals using hollows in trees are affected by change of the density of hollows caused by fire. Paradoxically, such animals may suffer significant mortality in intense fires, but they depend on occasional high-intensity fires as they result in hollows formation.
As different species exhibit different tolerances to different fire regimes, knowledge of these limits and pattern of their variations is very important for natural resource management.
3. How Fire is Currently Managed in Fire-Tolerant Ecosystems
There are three basic goals of fire management: life safety, property protection and protection of infrastructure. Comparatively recently environmental protection became to be considered as another important component of fire management.
Basically measures of fire management can be divided in prevention (proactive measures) and suppression (reactive measures).
Suppression is a method using variety of techniques, tools (airplanes, helicopters, other vehicles, pumps, explosives, etc.) and materials (water, sand, foam, chemicals) to suppress fire.
Prevention measures are the pre-emptive methods of reducing the risk of fire occurrence as well as lessening their spread and severity. They may include education with respect to preventing fires, restricting use of fire in wilderness, creating obstacles for fire spread (e.g. ditches) and prescribed (controlled burns).
Controlled burning is aimed to reduce fuel build-up (primarily dry wood and leaves) which may result in intense fires. It is primarily conducted in weather conditions which decrease the likelihood of intense fires (e.g. during cooler and/or wetter months). Important element of controlled burning is its regularity, which ensures that accumulated fuel is not sufficient to result in intense fire.
One of the specific types of controlled fires – a back burning – is somewhere between reactive and proactive measures of fire fighting. Back burning technique is starting small fires along a firebreaks (man-built or natural, such as river, road, ditch, etc.), aimed to “burn back” towards the main fire front. The basic goal of back burning is destroying fuel on the way of the wildfire to reduce it intensity and prevent from its throwing over a firebreak.
The major issue with using controlled burning is balancing its frequency so that it effectively decreases fuel built up and without affecting biodiversity (Whelan, Kanowski, Gill, and Andersen 2006). As it was mentioned earlier, different ecosystems have different vital attributes regarding withstanding fires and regenerating capacity in between them.
4. The Advantages and Disadvantages of a Policy to Suppress Fire
Currently suppression of fire in Australia is guided by almost universal policy to suppress fires wherever and whenever they start, even well away from settlements. Clearly such approach has a number of groundings:
- Protection of people, their properties and infrastructure.
- Protection of fire intolerant species, especially those that are endangered.
However, as any other radical solutions it has a number of disadvantages:
- Suppressing fires may interfere with natural life-cycle of the ecosystem. As it was demonstrated earlier, some species depend on periodic fires and resulting renewal of the ecosystem. Moreover fire fighting techniques and materials in some cases may have larger adverse effect on species then fire itself.
- Excessive growth of population of some animal and plants was historically regulated by periodic fires. Intrusion in this cycle may result in uncontrolled growth of their population and endangerment of other species.
5. Recommendations on the Best Way to Manage Fire for Ecosystem Health
Contemporary fire science and developments in fire management use the concept of fire regime as the framework core to understanding rather complex relationships between fire and ecosystem (Bradstock et al. 2002, Cary et al. 2003). This framework allows the development not only effective fire management, preventing human and property loss, but to achieve nature conservation goals in ecologically sustainable way.
For effective management of fires it is essential to understand that fires not only endanger human lives, property, infrastructure and ecosystem, at the same time they play an important role in shaping Australia’s environment and are necessary to maintain most Australian ecosystems and much of Australia’s biodiversity. For these controversial reasons managing fire presents significant challenges to Australia.
According to Kanowski et al due to such factors as the size of Australia and its relatively small population, fragmented landscape of European settlements, the fire prone characteristics of most Australian ecosystems, mean that it is nor feasible, nor practical to maintain fuels at sufficiently low levels or to suppress all fires in Australia (2005).
Therefore a strategic approach is required to minimize damage from fires. Strategic approach should elaborate two techniques – zoning and risk-based management.
Zoning requires landscape division according to the characteristics of certain zones. Such characteristics should include (but not limited to) zone’s propensity to fire occurrence, tolerance of its ecosystem to fires, proximity to rural and urban settlements and infrastructure elements, terrain specifics (i.e. rivers, mountains, etc.). According to these specifics different approach to fire prevention and responses to fire should be used.
Currently approach to zoning in Australia is mostly driven by concerns regarding human and infrastructure safety, i.e. controlled fires and vigorous fire suppression methods are used in zones adjacent to populated and industrial regions and different elements of infrastructure (water supply, road, railroads, etc.). Next step in fire management will be exercising zoned approach based on ecosystem specific, i.e. allowing fires were they are beneficial for ecosystem and do not threaten people and preventing or suppressing fires that resulted from extraordinary events and endanger life diversity.
Such zoning should be elaborated with techniques common for any risk management approach. Zoned risk approach can be performed according to the approach in the following table.
Table 3. Risk management approach to fires.
|Establish the context
|All relevant assets (social, economic, cultural and ecological) and objectives relating to each of them should be identified
|Identify the risks
|Factors with adverse effects in the event of fire should be identified with respect to the assets.
|Analyse the risks
|The likelihood of risks, vulnerability of the assets to this risks and probable impact should be identified using historical information and past experience.
|Evaluate the risks
|Tradeoffs between different assets (e.g. ecological vs economic) should be evaluated for different treatment options.
|Treat the risks
Based on the analysis performed treatments should be implemented to:
Source: Standards Association of Australia 1999,
Two steps should be performed continuously:· Monitoring and Review and Communicating and consulting. While first process ensures efficiency and relevancy of the framework, the latter provides valuable inputs and feedbacks from the process.
Such approach will result in differential addressing issues according to the strategic goals, while offering the best options for resolving tensions between different objectives and interest groups and in line with the principles outlined in the COAG Report which provide valuable guide on future of fire management in Australia (Ellis et al. 2004).
Fires are an integral component of the Australian environment. They pose a number of risks to life, health, property and infrastructure and to ecosystem.
Their total prevention in not feasible nor practical. Moreover such approach interferes with natural functioning of the Australia’s nature. Therefore, it is important to develop fire management system that would minimize risks through systematic risk evaluation, planning and management without interfering natural processes. It can be achieved through proper zoning, which would consider specifics of the ecosystems (such as tolerance and dependence of fires), and risk management techniques, which would consider assets, goals, risks and implication in order to properly address fires. This will help to achieve two ultimate goals protection of life and property and conservation of unique ecosystem of Australia.
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