Bushfires spark extensive search for answers
Key text
This topic is sponsored by the Australian Research Council Linkage Learned Academies Special Projects Grant.
They can start with a momentary flicker, they can burn for months, and their effects can scar landscapes and lives for years.
Bushfires are a natural and complex part of the Australian environment and have been for thousands of years. People as well as the natural environment have developed ways of coping with bushfires. Individuals and communities living in or near bushfire prone areas have established strategies to protect themselves and their homes from fires, these include removing all rubbish and leaf litter around buildings, implementing fire restrictions and preparing evacuation plans. While in the natural environment, many plants have evolved to adapt to, and cope with fires.
Research is now underway on many fronts to determine not only how to prevent bushfires, but also gain further insight on their devastating effects. The areas being looked at include how repeated fires affect local communities, the environment and our native plants and animals, as well as the extra dangers brought about by climate change and drought.
Turning up the heat
In the summer of 2002-2003, raging fires burned through some four million hectares across five Australian States and the Australian Capital Territory. Hundreds of homes went up in flames, four residents caught in the infernos in Canberra were killed, and the damage to property and communities was incalculable.
The environment was also extensively affected, with the fires raging through forests, national parks, reserves and farm land, killing stock and native fauna, and torching trees and other plants. When the smoke cleared, one scientist predicted that it would still take around 200 years for some parts of the nation's forests to fully recover.
The official inquiry into the fires heard from some 500 people, and made nearly 60 recommendations on how Australians can better equip their communities to battle such catastrophic blazes. It also turned up the heat for researchers to come up with better information and ways to reduce fuel loads and lessen the effects on communities and the environment. That research is being carried out around Australia, with much of it involving the Bushfire Cooperative Research Centre (CRC), which was set up as the result of the 2001–02 fires in NSW.
Managing the bush to save lives and towns
One key area being looked at is the use of prescribed burns – how effective they are, and the effects of repeated burns on ecosystems. With prescribed burns, areas of bush are deliberately set alight in the cooler months with the aim of reducing the fuel loads, and thus helping to mitigate really big fires from arising. For instance, the Department of Environment and Conservation in Western Australia as part of its annual prescribed burn season, burns up to 100,000 hectares of the state's south-west forests. The department says prescribed burns also help maintain the biodiversity of ecosystems across the state, and rehabilitates vegetation after disturbances such as timber harvesting and mining.
Reports on conservation efforts in the Ngarkat Conservation Area.
(Natural Resource Management, Australian Government, Australia)
But prescribed burning is a contentious issue. Not everyone believes that it is an effective land management tool. One concern is the effect of repeated burns on animal and plant species. It's believed that inappropriate fire regimes since European settlement have already been responsible for the extinction of two bird species – the Kangaroo Island emu and the northern scrub robin – as well as endangering many other bird varieties. However, in a number of cases, the occurrence of wildfires have also led to a drop in wildlife populations. The fires in 2005 and 2006, which took place in the Ngarkat Conservation Park in South Australia were damaging to the habitat and the populations of the already threatened Western whipbird and the Mallee emu-wren.
Another key issue with the prescribed burns is how do we determine the best time between burns. A recent long-term study in parts of Kakadu National Park by the CSIRO raised concerns that overburning is leading to the disappearance of native wildlife species (Box 1: Fire in the tropical savannas region). The study suggested that some native populations needed to be fire-free for up to five years to ensure their long-term survival.
While in Queensland, the Bushfire Management Coordination Group has developed a strategy that recommends a range of fire cycles of up to 20 years for differing forest regions. It suggests that in dry open eucalypt forests, in the absence of natural fires, controlled burns should take place from 7 to 12 years apart in developed areas; but in less developed areas, burns should take place at intervals varying from 7 to 20 years.
Clearly, the fires will have an effect on the ecosystem, irrespective of whether or not they are man made. Research is required to identify the factors that determine whether this effect is positive or negative. In the Australian Alps, wildfires have an overall greater impact to the survival of Alpine ash forests than managed fires. However it is worthwhile to note that a burn regime of less than 30 years could wipe out Alpine ash forests (Box 2: Fire in the Australian Alps). The Alpine ash only produces seeds after it reaches maturity at an age of 30 years or more; fires occurring at a frequency of less than 30 years would therefore kill trees before they could produce seeds.
Explains the stages of growth of Mountain ash.
(Museum Victoria, Australia)
There are also however, examples in which the occurrence of fires actually help the regeneration of plants. The survival of the Mountain ash is dependent on the occurrence of fires. Mountain ash can only regenerate from seeds, and fire is essential to provide the right conditions for the germination of its seeds. But if fires occur before the young trees reach maturity and produce seed (50 years old), the species may be completely wiped out. The species may then be replaced by another species better adapted to cope with that specific fire regime.
In another example, plant species like the eucalypts regenerate from lignotubers, which are stimulated by fire to develop shoots. And a study has found that smoke from burning plant material promotes seed germination in a variety of Australian plants.
Studying the effects of prescribed burns
Provides information on research in fire management in south Western Australia.
(Bushfire CRC, Australia)
Australian researchers are looking at the ecological effects of repeated fires – either prescribed burns or wildfires – on the landscape over a period of 50 years. Satellite imagery is being used to help determine patterns of fire intensity and to help identify changes in the biota (the flora, fauna and microbes in the region) as a result of different fire regimes in forests across the south-west of Western Australia. Such research will give fire managers guidelines for the optimum frequency, season, intensity and extent of burning to better manage the land.
Other researchers are looking at how prescribed burns affect the resilience or 'ecological memory' of the south-west forests: how long it takes to recover to its former state and how productivity of the land is affected. It's hoped the findings will be able to better protect forests and ecosystems.
Contains information on research undertaken by the CSIRO investigating high intensity fire behaviour.
(CSIRO, Australia)
CSIRO scientists are currently investigating the effects of fuel load and the long term effects of prescribed burning on the behaviour of wildfires in dry eucalypt forests, which are found in many areas of Australia.
Sifting through the ashes
How to best manage the use of fire in the landscape has become more urgent in Australia (Box 3: Other burning issues). The nation is already the world's driest inhabited continent, and it is undergoing prolonged drought exacerbated by climate change.
It is likely that Australia will always have large fires, but with better land management and successful hazard reduction, the land and its people will be able to recover much more quickly from the trauma of fire.
Boxes
1. Fire in the tropical savannas region
2. Fire in the Australian Alps
3. Other burning issues
Posted January 2008.