Living in a land of fire
Professor Rob Whelan, University of Wollongong
Professor Peter Kanowski, Australian National University
Dr Malcolm Gill, Australian National University
Dr Alan Andersen, CSIRO Tropical Ecosystems Research Centre
prepared for the 2006 Australian State of the Environment Committee, 2006
Fire is an integral part of Australia’s natural environment, and of our cultural and social fabric. The first people on the continent learned to live in a fire-prone environment and to manage fire as part of everyday life. Fire was their principal land management tool, and the early European explorers frequently commented on the presence of smoke and recently burned country. European colonists feared bushfires and used fire to help clear native vegetation for agriculture; they sought to prevent and suppress bushfire to protect life and property. Contemporary Australian land managers are using fire in primary production, for biodiversity conservation, and for the protection of life, property and other assets.
Bushfires will occur at some time in most parts of the Australian continent, although they might be very infrequent in some climatic zones, such as those dominated by rainforest or wet eucalypt forest. The average interval between fires in southern rainforests could be hundreds of years. Between four per cent and ten per cent of the continent (about32–80 million hectares) might be burnt in a typical year, thereby suggesting an average interval between fires for the continent of about 15 years: in the severe fire season of 1974–75, about 15 per cent of the land area of Australia was burnt (Luke and McArthur 1978), and in 2002–03, a severe fire year in south-eastern Australia, seven per cent (54 million hectares) was burnt. Years in which bushfires cause the most serious threats to lives and property in Australia are typically serious drought years in southern Australia.
The greatest extent of bushfires in any one year is almost invariably in the savannas of northern Australia. Fires at any one point can occur every second year in some places. In some seasons, fires extend into the semi-arid and arid interior, especially following the rare years of significant arid-zone rainfall. For example, rainfall in Central Australia was well above average in 2001, and consequently abundant grass growth in 2002 fuelled the most extensive burning there for 25 years. The greater the average extent of fires, the shorter the average interval between them.
Given the extent and significance of bushfires in Australia, fire features in most themes in any assessment of the state of the Australian environment. For example:
- fires affect the atmosphere through the local and regional impacts of smoke on air quality, and through the global effects of carbon being released from biomass burning
- fires affect biodiversity both in the short term through impacts on individual organisms and the populations of which they are part, and over the longer term through effects on species, ecosystems and habitat
- the effects of fires on human settlements, through threats to human life and property, can be very significant, but can also be substantially mitigated through good planning and preparedness, and effective suppression
- fires affect inland waters by altering catchment hydrology and water quality in rivers and dams, and because they are integral to the ecology of wetlands
- fires affect land through both the landscape- and local-scale impacts of uncontrolled fire, and the managed use of fire for fuel reduction and as a tool in farming and forest management systems
- fire has shaped much of Australia’s natural and cultural heritage: Indigenous Australians cared for their country with fire, and the cultural heritage of graziers depends in part on the use of fire; but fire can also threaten sites and structures of cultural significance to both Indigenous and non-Indigenous Australians
- the links between fire and coasts and oceans and between fire and Antarctica are not so obvious, but are nevertheless real. Fires in coastal zone vegetation can impact on coastal and near-shore marine environments, and global climate change, to which carbon release by bushfires contributes, is affecting Antarctica.