Aboriginal Fire Starting - YouTube
www.youtube.com/watch?v=9cUb2ggtFbIOct 10, 2007 - Uploaded by Gregory FowlerFire Starting Demonstration by the Aboriginals of Australia.
By examining fossilised gum tree pollen, researchers at the Australian National University in Canberra have dated the unique regenerative capacity of eucalypts to around the same time that Australia's rainforests began to recede 62 million years ago – shortly after the extinction of the dinosaurs.
Up until now, most studies have argued that bushfires have only been common for the past 15 million years.
Smoking gun
"Our work suggests the ancient ancestors of the eucalypt moved out of the rainforest and into the woodlands that you see today, at about the same time as this [regenerative] adaptation arose," says study author Professor Michael Crisp. "It's a smoking gun of evidence that...both things originated at the same time as fire became a presence in Australian vegetation."
Many trees have dormant 'epicormic' buds underneath the bark that sprout when the tree is damaged by storms or drought – but eucalypts have evolved a unique variation of this tissue. "This tissue is very deep in the wood of the eucalypt tree and is very resilient, springing into life with damage from fire," Michael says.
"In other parts of the world that have similar environmental conditions to Australia, such as California with its oak-dominated forests, a severe bushfire will kill everything above ground. Eucalypts, however, have developed a unique capacity to recover from fire," he says.
Michael's team argue that the evolution of this ability in gum trees may have been part of a cycle which – along with the changing climate – caused Australia to become much more arid and led to the rainforests being replaced by dry eucalypt forests.
"We think that there was a feedback loop between the eucalypt surviving fires and creating an environment that favoured the eucalypt,"
BUSHFIRES ARE PART OF the Australian landscape. They have been around for an estimated 60 million years and they are a regular cycle in our climate.
This year's relatively wet conditions may help keep devastating bushfires at bay in forested regions near the coast, all the while setting up ideal conditions for burning throughout central Australia. But predicting the severity of a given bushfire season is never an easy task.
"The weather conditions that set the scene for prolific unmanaged fire in the landscape are the same weather conditions that make the urban environment really vulnerable," says Justin Leonard, a CSIRO research scientist who specialises in bushfire urban design.
Worst fires have high temperatures, low humidity and strong winds
In urban areas, fine fuels such as mulch, timbre decks and housing materials dry out in high heat and low humidity, which helps feed the flames. But not all urban areas are at high risk.
"Menacing bushfires that cause death and house loss aren't universal across Australia," Justin says. "They're quite focused to smaller regions on the Australian continent, and that's mainly because the severe fire weather that sets the scene for really bad fires [in urban areas]...only occurs in certain areas."
Bushfire management
Researchers attribute this to relatively mild fire weather conditions, the state's sparse population and community awareness.
While New South Wales, Canberra, South Australia and Tasmania have all experienced devastating bushfires in recent years, it is Victoria—particularly in regions near Melbourne—that stands out as a hotbed for bushfire activity. Four of the five deadliest fires on record in Australia have been in Victoria.
Five deadliest bushfires on record
3. Black Friday (VIC), 13-20 Jan 1939 Drought conditions and water shortages also preceded Black Friday, but the usual combination of high temperatures, strong winds, and low humidity finally triggered fires throughout bush communities near Melbourne. Well-meaning locals and graziers made the problem worse by trying to use controlled burns to protect themselves from disaster, only to see their good intentions help spread the flames. In all, 71 people were killed and 650 houses were destroyed. A Royal Commission investigation into the fires led to increased fire awareness and prevention efforts throughout Australia.
4. Black Tuesday (TAS), 7 Feb. 1967 An unusually abundant spring covered Tasmanian forest floors with litter, providing excess fuel for the bushfire season. Strong northerly winds and high temperatures coupled to help fuel at least 80 different fires across southern Tasmania, which swept over the south-east coast of the state and came within 2km of central Hobart. The fires killed 62 people and razed almost 1300 homes.
Bushfire simulation improves prediction
Research boosts fire management theories
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