Bushfire: causes, behavior, impacts and management
A bushfire is a wildfire that occurs in the scrub, woodland or grassland of Australia and New Zealand. This article explains causes, behaviour, ecology, risks, notable events and management strategies.
A bushfire is a form of wildfire occurring in the open vegetation of the Australian and New Zealand countryside. In local usage "the bush" refers to scrub, scrubland, woodland or grassland and the term covers a wide range of fire types from fast-moving grassfires to slow-moving surface or intense crown fires. Bushfires are a seasonal hazard in Australia and New Zealand, with timing and behaviour shaped by regional climate and vegetation.
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Characteristics and fire behaviour
Bushfires vary by fuel type, weather and topography. Grassfires spread rapidly across open country; forest and woodland fires can climb into canopies producing crown fires that travel faster and generate embers that start spot fires far ahead of the main front. Key weather drivers include high temperatures, low humidity and strong winds; steep slopes and continuity of fuel also accelerate fire spread. Many Australian plant species, notably Eucalyptus, contain volatile oils that increase flammability and encourage intense burning.
Origins and notable events
Ignitions arise from lightning, agricultural burns that escape control, equipment failures, fallen powerlines and deliberate arson. Some seasons produce extreme fire conditions. The 2009 Victorian bushfires (often called Black Saturday) were among the deadliest and most destructive recent events, with large loss of life and property documented. Other seasons have burned millions of hectares and caused widespread ecological and social disruption.
Ecological role and impacts
Fire is a natural process in many Australian ecosystems and some plants regenerate or reproduce only after fire. At moderate frequency and intensity, fires can maintain biodiversity and reset growth. However, very frequent or extremely intense fires can damage soil, reduce habitat for wildlife (including iconic species), and allow invasive species to gain a foothold. Smoke also affects air quality and human health over wide regions.
Management and preparedness
Approaches to reduce bushfire risk combine prevention, mitigation and response. Common measures include planned hazard-reduction burns to reduce fuel loads, construction of firebreaks, community education, strict controls on activities during high fire danger, and investment in firefighting resources. Early warning systems, land-use planning and clear evacuation procedures are critical for protecting lives and property.
Distinctions and further reading
- Bushfire vs wildfire: terms are often used interchangeably, but "bushfire" is regionally specific.
- Types: grassfire, surface fire, crown fire and spot fire denote different behaviour and hazards.
- Management: combining traditional indigenous burning practices with modern science is increasingly discussed as a way to reduce catastrophic risk.
For more information on terminology, ecology and safety measures consult authoritative sources and local fire services; education and preparedness remain the most effective defence against bushfire harm. See related resources: wildfire overview, scrublands, woodland ecology, grassland fires, Australian fire services, New Zealand guidance, Eucalyptus and flammability, Black Saturday.
Definition
Australian bushfires are generally defined as uncontrolled fires of grass, scrub, brush and forest. There are two main categories based on terrain type:
- Bushfires in forested, hilly and mountainous areas:
These areas are sparsely developed, are not used for agriculture, and many of their forested areas are national, state, or other parks. Steep terrain increases the intensity and speed of fires, which pose a great danger to settlements and residents.
- Bushfires in flatlands or grasslands:
In flat or less hilly terrain, mostly covered by grasses and shrubs, brush fires can spread immensely fast, as they are often fanned by strong and hot winds and favoured by dry and easily ignited vegetation. Fires in grasslands can reach an intensity similar to hill country. Here, too, there is a great danger to human settlements. However, they are easier to forecast and contain regionally; moreover, these areas are easier for fire brigades to reach.
Natural triggers of bushfires are lightning strikes, sometimes these fires are caused by careless handling of cigarettes or by arson; occasionally fires start unintentionally during agricultural use of areas.
During the 2019/2020 bushfires, fires also occurred in subtropical Gondwana rainforests in Australia, some of which had not burned for more than 1000 years. Fires also occurred in wet eucalypt forests due to drought conditions that had lasted for several years, as well as in dried-up swamps and soils of organic material after the water table there had dropped.
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Painting Black Thursday (Fire of 1851) by William Strutt (1825-1915)
History
Bushfires of natural origin have been present on the Australian continent for millions of years, triggered by lightning strikes and thus significantly shaped much of the landscape of the Australian continent before the arrival of man. Aboriginal people used fire for hunting and landscape management for many thousands of years, usually in the cooler seasons and when winds were favourable. Fires set in this way encouraged the growth and expansion of grasslands and facilitated hunting, as well as reducing the stock of combustible material and facilitating penetration into inhospitable areas with dense vegetation.
The increased occurrence of human-caused bushfires allowed fire-resistant plant species to spread, especially eucalypts. With their rapid formation of shoots after fires, woody stem bulges, and fire-resistant seeds, many plants adapted evolutionarily. Some species produce flammable oil, which increases fire effectiveness, eliminating non-fire resistant plant species in the surrounding area.
According to a summary published by the Australian CISRO in 2012, Australian fire and land management agencies dealt with 268,398 bush and grass fires between 2002 and 2007. That was an average of 53,680 fires per year. Assuming this trend had been constant throughout the 20th century, there would have been a total of about 5.5 million fires from 1901 to 2000.
Some of the most dangerous and large Australian bushfires since the arrival of European settlers have been (in chronological order):
| Fire | Area | Burnt area | Date | Dead | Destruction |
| Bushfire in Victoria 1851 | Victoria | estimated 50,000 km² | February 6, 1851 | approx. 12 | 1 million sheep, thousands of cattle |
| Red Tuesday Bushfires | Victoria | 2,600 km² | February 1, 1898 | 12 | 2,000 Buildings |
| Bushfire 1926 | Victoria | February-March 1926 | 60 | 1,000 houses | |
| Bushfire in Victoria 1939 | Victoria | 20,000 km² | December 1938 - January 1939, especially on 13 January 1939 | 71 | 3,700 houses |
| Bushfire 1944 | Victoria | approx. 10,000 km² | 14 January - 14 February 1944 | 15–20 | more than 500 houses |
| Bushfire 1951-1952 | Victoria | Summer 1951-1952 | 10 | ||
| Black Sunday Bushfire (1955) | January 2, 1955 | 2 | |||
| Western Australia Bushfire 1961 | 18,000 km² | January-March 1961 | 0 | 160 houses | |
| Bushfire 1962 | Victoria | 14-16 January 1962 | 32 | 450 houses | |
| Southern Highlands Bushfire | 5-14 March 1965 | 3 | 59 houses | ||
| Tasmanian bushfire of 1967 | estimated 2,640 km² | 1967 | 62 | 1,293 houses | |
| Dandenong Ranges Bushfire | Victoria | 19 km² | February 19, 1968 | 53 houses and 10 other buildings | |
| Bushfires in the Northern Territory 1968-1969 | 400,000 km² | 1968–1969 | Killarney - Top Springs | ||
| Bushfires in the Northern Territory 1969-1970 | Northern Territory | 450,000 km² | 1969–1970 | Dry River - Victoria River | |
| Bushfire in South Australia 1969 | Victoria | January 8, 1969 | 23 | 230 houses | |
| Northern Territory Bushfires 1974-1975 | Northern Territory | 450,000 km² | 1974–1975 | Barkly Tableland, Victoria River District, near Newcastle Waters | |
| 1974-1975 Western Australia Bushfire | Western Australia | 290,000 km² | 1974–1975 | ||
| 1974-1975 South Australia Bushfire | South Australia | 170,000 km² | 1974–1975 | ||
| Western Districts-Bushfire | Victoria | 1,030 km² | February 12, 1977 | 4 | 116 houses and 340 buildings |
| Western Australia Bushfire 1978 | Western Australia | 1,140 km² | April 4, 1978 | 2 | 6 buildings (the falling wind in the early evening is believed to have saved the towns of Donnybrook, Boyup Brook, Manjimup and Bridgetown) |
| Northern Sydney Bushfire | New South Wales | 1979 | 20 homes in Sydney, the fire spread to Ku-ring-gai-Chase National Park. | ||
| Ash-Wednesday-Bushfires | South Australia and Victoria | 4,180 km² | February 16, 1983 | 75 | about 2,400 houses |
| Central Victoria Bushfire | Victoria | 508 km² | January 14, 1985 | 3 | > 180 houses |
| Eastern Seaboard Bushfires 1994 | New South Wales | 27 December 1993 - 16 January 1994 | 4 | 225 houses | |
| Wooroloo Bushfire | Western Australia | 105 km² | 8 January 1997 | 0 | 16 houses |
| Dandenongs Bushfire | Victoria | 4 km² | 21 January 1997 | 3 | 41 houses |
| Lithgow Bushfire | New South Wales | 2 December 1997 | 2 | ||
| Perth-and-SW-Region-Bushfire | Western Australia | 230 km² | 2 December 1997 | 2 (21 injured) | 1 House |
| Linton Bush Fire | Victoria | 1998 | 5 | There were 5 firefighters who died in the line of duty on December 2, 1998. | |
| Black Christmas Bushfire | New South Wales | 3,000 km² | 2001–2002 | 0 | 121 houses |
| 2002 Northern Territory Bushfire | Northern Territory | 380,000 km² | 2002 | ||
| Bushfire in Canberra 2003 | 2003 | 4 | nearly 500 houses, Canberra | ||
| Bushfire in Victoria 2003 | Victoria | > 13,000 km² | 8 January - 7 March 2003 | 41 houses. The bushfire burned for 59 days. | |
| Tenterden | December 2003 | 2 | (21,100 km² of forest burned during the 2002-2003 bushfire season in southwestern Western Australia) | ||
| Eyre Peninsula Bushfire | 8,900 km² | 10-12 January 2005 | 9 | about 50 houses | |
| Central Coast Bushfire 2006 | New South Wales - Central Coast | New Year's Day 2006 | |||
| Jail Break Inn Fire | New South Wales - Junee Shire | 300 km² | New Year's Day 2006 | 0 | 20,000 head of cattle. 7 houses, 7 combines and 4 sheep pens destroyed. 1,500 km of fence was damaged. |
| Victoria bushfire 2005 | Victoria | 1,600 km² | December 2005 - January 2006 | 4 | 57 houses, 359 farm buildings, 65,000 head of livestock. The bushfires occurred in the Stawell, Moondarra, Anakie, Yea and Kingla regions. |
| Grampians Bushfire | Victoria | 1,840 km² | January 2006 | 2 | 25 houses destroyed, 62,000 sheep and 500 cattle burned. |
| Pulletop Bushfire | New South Wales - Wagga Wagga | 90 km² | February 6, 2006 | 0 | 2,500 sheep, 6 head of cattle, 3 vehicles, 2 straw barns and 50 km of fence was destroyed |
| The Great Divides Fire | Victoria | 10,480 km² | 1 December 2006 - March 2007 | 1 | 51 houses |
| Bushfires in Victoria 2006/2007 | Victoria | approx. 12,000 km² | 1 December 2006 - 7 February 2007 | 1 | 41 houses destroyed. The bushfire burned for 69 days |
| Dwellingup Bush Fire | 120 km² | February 4, 2007 | 0 | 12 houses destroyed. | |
| Kangaroo Island Bushfire | South Australia | 950 km² | 6-14 December 2007 | 1 | Flinders Chase National Park (630 km² or 85 % of the area of the national park burnt) |
| Boorabbin National Park Bushfire | Western Australia | 400 km² | 30 December 2007 | 3 | Overhead power lines and Great Eastern Highway were destroyed and not usable for 2 weeks |
| Black Saturday Bushfires | Victoria | > 4,500 km² | 7 February 2009 - 14 March 2009 | 173 | > 2,029 houses and 2,000 other structures. In the course of this bushfire, three lightning-generating fire clouds, so-called pyrocumulonimbus, were formed, which rose to a height of up to 15 kilometres. |
| Toodyay Bush Fire | Western Australia | > 30 km² | December 29, 2009 | 0 | 37 houses |
| Lake Clifton brush fire | Western Australia | > 20 km² | 11 January 2011 | 0 | 10 houses destroyed |
| Roleystone-Kelmscott Bush Fire | Western Australia | > 15 km² | 6-8 February 2011 | 0 | 72 homes destroyed, 32 damaged, the Buckingham Bridge on Brookton Highway collapsed and had to be replaced with a temporary bridge. |
| Bushfires in Australia 2019/2020 | New South Wales, Queensland, South Australia, Victoria, Western Australia, Tasmania, Northern Territory | > 126,000 km² | August 2019 - March 2020 | 33 directly + estimated 445 from smoking | 5,900 buildings including 2,800 homes destroyed; 80% of Australia's residents hit by smoke, thousands treated in hospitals for smoke-related illnesses at a cost of AUSD 2 billion (1.2 billion euros), an estimated additional 445 deaths from smoke-related illnesses |
| Bushfire Fraser Island | Queensland | > 800 km² | From mid-October 2020 |
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Author
AlegsaOnline.com Bushfire: causes, behavior, impacts and management Leandro Alegsa
URL: https://en.alegsaonline.com/art/15591
Sources
- burarra.questacon.edu.au : "Monsoonal Climate"
- bom.gov.au : "The Bushfire Threat"
- ga.gov.au : "What is a bushfire"