Bushfire

Bushfire refers to the burning of bush, forest or woodland area. Bushfires are natural phenomena. Bushfires are an intrinsic part of Australia’s environment. Natural ecosystems have evolved with fire, and the landscape, along with its biological diversity, has been shaped by both historic and recent fires. Though common to Australia, bushfires also occur in other parts of the world.

The 2009 Victorian bushfires destroyed 750 homes and burnt over have 330,000 hectares till, showing no sign of being contained till mid February 2009.

According to the Australian Bureau of Transport and Economics' 2001 report, between 1960 and 2000, major Australian bushfires have cost A$2.5 billion. These bushfires also resulted in the death of around 250 people and the destruction of 4,554 homes.

Why should I be aware of this?

• Every summer Australia is in danger of bushfires that devastate lives, eucalypt forests and rage into the suburban fringes of major cities.
• With climate change and global warming, the frequency and severity of bushfires have been forecast to increase.
• Many of Australia’s native plants are fire prone and very combustible while numerous species depend on fire to regenerate.
• Fire is both feared and harnessed. Indigenous Australians have long used fire as a land management tool and it continues to be used to clear land for agricultural purposes and to protect properties from intense, uncontrolled fires.
• Current fire management practices aim to protect people and property, while simultaneously maintaining biodiversity values. However, these objectives are often in conflict as prescribed burning for fuel reduction can eliminate rainforest species.
• As well as human impacts, long-term bushfire effects include loss of bird and animal habitats, reduced soil fertility lasting decades and contamination of water catchments with ash and debris.

All about bushfires

Bushfires in Australia occur either as a Grass Fire or Forest Fire.

1. Grass Fires -- Grass fires usually occur on grazing and farm land. They are fast moving, passing in 5 to 10 seconds and smouldering for minutes. They have a low to medium intensity and end up destroying
2. Forest Fires -- Australia’s forests are largely made up of eucalyptus trees that once caught alight are very difficult to control and extinguish due to the high amounts of flammable vapour from its leaves. This causes large fireballs in the upper storey of the forest and large clouds of smoke blanket the ground and any aerial observations that need to be made. Forest fires are generally slower moving, but have a higher heat output. This means they pass in 2 to 5 minutes, but they can smoulder for days. Fire in the crown of the tree canopy can move rapidly.

Causes of bushfires

Bushfires can originate from both human activity and natural causes.

• Natural causes -- Lightening is the predominant natural source, accounting for about half of all ignitions in Australia.
• Man made causes --Bushfires can be caused deliberately or accidentally by humans. Some of these causes are:
  • A fire left unattended at a camp.
  • Open fire on a dry windy day.
  • The glass from a bottle or mirror can cause a small flame to become a raging wildfire.
  • A cigarette or match that has not been put out.
  • Flammable chemicals that are left in hot areas or in the sun.

Ways to control bushfires

Water-bombing planes such as helicopters and light aircrafts first make observations about the direction the fire, where to build firebreaks, locating nearby homes, businesses, other buildings and livestock and then try to douse the fire.

Backburning during a fire removes the fuel from the path of the fire. Depending on wind and the nature of the fire, a section of up to half a mile may need to be burned, at a safe distance from the main fire.[1] This fire is very carefully controlled, and there is some risk involved.

Controlled burning (also sometimes called backburning) is carried out outside of the bushfire season. By burning earlier, before the fuel load builds up, and before the weather makes the fire difficult to handle, the most dangerous fires may be avoided. One consideration is that occasional fierce fires are a part of the natural cycle - this must be balanced with the need for public safety, and the effect on species which are already endangered due to human impact or other reasons. On the other hand, firefighting efforts may lead to longer periods between fires than might have naturally occurred, which means a greater fuel load and more severe fires when they do eventually occur.

Bushfire disasters in Australia

There are a few bushfires that can be categorised as natural disasters. Some of these were in:

• South Australia and Victoria in 1983, which claimed 76 lives and was designated as “Ash Wednesday”.
• Southern Victoria, 1969 when 23 passed away.
• New South Wales (1968) in the Blue Mountains and coastal region. 14 lives were taken during this fire.
• Hobart and Southern Tasmania, 1967, which left 62 dead.
• Victoria, 1939 and was named “Black Friday”. It took 71 lives.

Bushfire and environment

Bushfires result in habitat loss of many species. The 2009 bushfires burnt through the habitats of the Sooty Owl, Spotted Tree Frog, Ground Parrot and the Barred Glalaxias Fish. It might have critically endangered Leadbeater’s Possum.

CopperBytes

• High temperatures and low rainfall make bushfires a natural hazard. Natural tree oils in native eucalypt forests fuel fireballs.
• South-eastern Australia includes areas which are prone to the most severe and frequent wildfires in the world.
• A Fire Front is the leading edge of a moving fire.
• Most fire fighting deaths have occurred following a sudden change of wind direction.
• Unfortunately, the majority of people who lose their lives in bushfire do so because of poorly timed and poorly planned last minute evacuation
• In drier seasons the fire danger is much higher.
• In 1982/83 South-east Australia experienced severe drought conditions. On 16 February 1983, Victoria and South Australia experienced a very windy hot, dry day. In Melbourne the temperature reached 43°C with relative humidity of 6%. The “Ash Wednesday” bushfires erupted on this day.

References

• What is a bushfire? Geoscience Australia
• Bushfire CRC
• Bushfire CRC education
• Bushfires - Get the Facts
• FACTBOX - Key Facts about Australia's Bushfires:Reuters
• Fears for endangered species after bushfires