VICTORIA should substantially increase its fuel reduction burning program to reduce the risk of bushfires – possibly by almost 500 per cent – and there is no need to wait for more research. To delay increasing the amount of forest burnt is ”an invitation for further trouble”, the Bushfires Royal Commission has been told.
Planned burns will ”stop” a bushfire if the burn is only one or two years old and have a ”profound” effect on decreasing the rate of spread of a bushfire if it is only three years old, the commission heard. Planned burns that cut the amount of forest fuel reduced the number of bushfires and delivered a benefit even when challenged by ”extreme burning conditions”, bushfire behaviour expert Phil Cheney said.
The mitigating benefits of planned burns could last as long as 20 years, he said. The comments were made during a panel discussion featuring seven fuel reduction experts.
The panel called for planned burns on 5-10 per cent of Victoria’s public land each year. This would be a vast increase on the planned burning currently done; the present annual target of 130,000 hectares equals about 1.7 per cent of public land.
”A good prescribed burn will stop a fire, if it’s large enough, in the first one and perhaps two years after burning,” said Mr Cheney, a former CSIRO research scientist. ”At three years it still has a profound effect in decreasing the rate of spread. And the reduction in rate of spread may persist for five to eight years.
”The key to a burning program for wide-scale protection is to have the blocks strategically located across the landscape in a pattern that, when repeated, large fires are going to sooner or later run into one of these low fuels and be checked suppression of the fire in subsequent hours or days after the extreme weather will be made much easier.”
Mr Cheney strongly questioned the growth in spending and emphasis on fire suppression in the approach to fire management, relative to the focus on planned burns.
”Our current system has failed. Expansion to bigger and better suppression systems is going to fail. It has failed in the United States, and if the biggest and most powerful country in the world can’t devise a physical suppression system to suppress a fire without prescribed burning, then we surely should be taking some notice about that.”
In a joint statement presented to the commission, the panel said planned burns reduced the intensity of bushfires and helped improve the success of suppression efforts. They also reduced the rate of spread of a fire, the risks to some ”ecological values” and the risk to life and property.
Professor Mark Adams of the University of Sydney said it was sensible to do planned burns in water catchments, which he said helped smooth out ”boom and bust” water harvesting cycles that followed major bushfires.
Planned burns in catchments also protected water quality from ash and sediment.
Asked when the suggested rise in planned burns should begin, Professor Adams said: ”We must commence now. There’s no reason to wait delay is just an invitation for further trouble.”
Dr Kevin Tolhurst of Melbourne University said fuel-reduction burns reduced the number of bushfires.
”We know in very recently burned areas that the number of ignitions, whether it be from lightning or from burning embers blowing into those areas, the take rate is extremely low or perhaps zero,” he said.
”So it will reduce the number of fires in the landscape. It might not prevent them, but it certainly reduces their intensity and their rate of spread.”