Burning the fire continent
By Dr John Kanowski, AWC Chief Science Officer
Australia – a fire continent
Following years of drought, exacerbated by heat-wave conditions, the 2019-20 wildfires burnt over 10 million hectares of south-east Australia’s forests and woodland, killing 34 people and incinerating countless animals. More than 100 threatened species had over half their habitat blackened by the fires, while the animals that survived remain at increased risk of predation by feral cats and foxes.
The fires, burning through and around major population centres, made many Australians acutely aware of the importance of effective fire management. However, this issue has long been a central concern for forest and conservation managers.
Australia is particularly susceptible to fire, due to its climate and vegetation. Wildfires have shaped its environment for millennia. The particular frequency, intensity and seasonality of fire prevailing at a location – the ‘fire regime’ – is a key driver of the ecology of Australian ecosystems, affecting the structure, composition and dynamics of the vegetation and the habitat it provides for fauna. Many native plants exhibit adaptations to fire. Some require fire to germinate and establish. In fire- prone ecosystems, many species of wildlife have a remarkable capacity to survive the passage of fire, provided it is not intense, and many species favour the resources available after fire. However, large wildfires such as those that burnt much of south-east Australia in 2019-20 are generally devastating to wildlife. Repeated intense fire events alter ecosystems – favouring species that tolerate repeated disturbance – and eliminating fire-sensitive species.
Fire management in Australia
Fire has been part of the tool kit of humans for a very long time. Indigenous Australians may well have used fire to manage country from the time they settled the continent. On this basis – and this entails a major paradigm shift in our understanding – the Australian bush is the product of an unimaginably long history – likely tens of thousands of years – of deliberate fire management. Certainly, by the time Europeans arrived, Aboriginal people demonstrated great facility in use of fire. Traditional fire management practices continue to the present in parts of central and northern Australia, and typically result in a fine-scale, patchy mosaic of vegetation at different ages since fire and unburnt vegetation. This fire regime generally protects wildlife from the impacts of intense wildfires, which rarely burn through such actively-managed country. Unfortunately, less is known of traditional burning practices in the environments of southern Australia.
European colonisation resulted in the dispossession of Aboriginal people and the disruption of their fire management practices. Across much of the country, a wildfire regime took hold. In northern Australia, this resulted in the annual conflagration of 20-30 million hectares of savannas in the late dry season. In arid Australia, massive landscape-scale wildfires followed periods of extensive rainfall, at intervals of up to 30 years. In south-east Australia, extensive wildfires have burnt through the forests at approximately decadal intervals, most recently this last summer.
Piccaninny Plains late fire frequency. Late fire frequency is the number of years each area has been burnt in a late fire in the nine years for each time period.
AWC’s approach to fire management
AWC’s mission is the effective conservation of Australia’s wildlife and their habitats. Effective fire management is a primary focus of AWC’s operations. At present, our approach to fire management is best articulated for properties in northern and central Australia, where we have a good understanding of ecologically-appropriate fire regimes and how to implement those regimes.
For each property in these regions, AWC develops fire management strategies, drawing on the available ecological knowledge as well as the practical experience of our land managers. While the particulars of each strategy vary between sites, common key objectives include the protection of life and property, the conservation of biodiversity and landscape-scale control of certain weeds. This is achieved through managing patterns of fire, in particular, through deliberately lighting relatively ‘cool’ burns to strategically reduce fuels across the landscape with the aim of reducing the likelihood of large, homogenous wildfires. In northern Australia, there is generally good alignment between conservation-oriented fire management and abatement of greenhouse gas emissions. Given that intense, large wildfires are potent sources of greenhouse gases, AWC’s fire management also makes a contribution to reducing rates of global warming. Where we are engaged in partnerships with Indigenous landholders, such as on Dambimangari and Wilinggin countries, fire strategies also address the interests and concerns of our partners, such as the protection of cultural sites and involvement of culturally- appropriate managers in burning programs.
Each year, a burn plan is developed for each property by AWC land managers, ecologists and partners, to give effect to the fire management strategies. These annual burn plans provide detailed guidance for operations staff, noting areas to be burnt from the ground, the location of firebreaks, and flight lines for aerial-delivery of incendiaries. They are built up from detailed knowledge of country and informed by analysis of fire scars from satellite imagery. In northern Australia, annual fire management is a necessity.
At the end of each year, specialist technical staff in AWC’s science program download the satellite data, conduct additional interpretation of fire scar data, and produce maps and analyses of fire patterns. This information allows us to assess the effectiveness of our fire management against a range of metrics and to plan for the following year’s fire management.
Results of AWC’s fire management
Implementation of AWC’s fire management program has halved the extent of wildfire in properties we manage across northern Australia. This holds true for Western Australia, Northern Territory and Queensland and indicates that our general approach to fire management in northern Australia is effective, despite differences between sites and details of the approaches adopted by each manager.
Table showing reduction in late dry season wildfire before and after AWC management across our north Australian sanctuaries.
Research by AWC ecologists has shown that a reduction in the extent and frequency of wildfire has positive consequences for wildlife. In the Kimberley region of WA, for example, AWC’s fire management has resulted in an increase in the abundance of small mammals, especially where grazing is also controlled. One of the key factors driving the increase in small mammal populations is reduced predation by feral cats in landscapes where more cover is retained due to better fire management.
The abundance of small mammals at AWC’s wildlife sanctuaries in the Kimberley increases with a reduction in the frequency of late dry season wildfires, particularly on destocked sites.
AWC will continue to refine our fire management program based on analysis of its outcomes, including evidence from our research on the response of plants and animals to fire regimes. Like other conservation managers, we need to work out how best to implement fire management in our southern forests, given their long history of modification, and their occurrence within urbanised landscapes where methods employed in remote Australia do not readily apply. Across the continent, implementation of effective fire management will only become more important as temperatures increase with climate change.
Small mammal populations, like those of the Pale Field Rat (Rattus tunneyi), have benefited significantly from AWC’s fire management programs.
AWC’s fire management program in the Kimberley
While AWC has a network of wildlife sanctuaries and partnership sites across Australia, our largest footprint (by area) is in the Kimberley, in north-west Western Australia. This region largely supports savanna vegetation, characterised by various eucalypts, boabs and other trees above a grassy understorey of spinifex and tussock grasses. The grasses grow during the wet season, and cure over the long dry season. Without deliberate fire management, such as practised under Aboriginal fire management, the savannas are prone to extensive wildfire from lightning during the build-up season. Without deliberate fire management, nearly half the savannas in the Kimberley burn annually, the majority in late dry season wildfires.
Mornington Fire history 2006 and current. Shows seven year fire history before/after AWC management for Mornington-Marion Downs-Tableland.
AWC began its regional fire management program, EcoFire, in the Kimberley in 2007. The program involves AWC properties, neighbouring pastoral stations and Indigenous lands. In recent years, AWC has expanded the area under fire management in the region to include Yampi Sound Training Area and the Dambimangari and Wilinggin Aboriginal Corporations partnerships, such that it now extends over 6.5 million hectares. This is the largest non-government fire management program in Australia.
Compared with the situation prevailing in the region, the implementation of the EcoFire program has resulted in a halving of the average annual extent of wildfire, from 31 to 15 per cent, brought about by an increase in prescribed burns in the early dry season and targeted suppression. Early dry season burns tend to be cooler and burn more patchily than late dry season wildfires.
AWC’s ecological survey program has demonstrated that small mammals, seed-eating birds and riparian (streamside) birds have responded positively to the reduction in wildfires.
In 2020, COVID-19 has posed an unexpected challenge to AWC’s fire program in the Kimberley, as it has to all of our lives. Not delivering fire management this year was simply not an option. Quick thinking by AWC staff, our partner organisations and contractors resulted in our Kimberley team enforcing strict quarantine measures – the entire team as well as all vehicles (including two helicopters) and equipment were required to self-isolate for 14 days. As a result, the fire management program is being implemented in full.