Research scientist Lachlan McCaw led a team that studied the effects that previous planned or unplanned fires had on the spread of the disastrous Black Saturday fires a year ago in Australia. Unsurprisingly, he concluded that the intensity was reduced and the areas provided anchor points for firefighters, but larger prescribed fires were more effective than small ones.
DUH. To many of us this is intuitive, but documenting this data can help to rebut the uninformed rants of those in Australia that are opposed to prescribed fires.
Here is an excerpt from a report in The Australian:
Dr McCaw said that across the areas burned on Black Saturday, there was no evidence that small-area fuel reduction had curbed the fires, but strong evidence of an impact where planned or unplanned burns had occurred within four years and over broad areas of more than 600ha.
Where the Kilmore fire, burning with great intensity about 3pm on Black Saturday, met a relatively small area of four-year-old growth, it was quickly outflanked.
About 6.30pm, when the fire met a 1600ha area burnt by wildfire in January 2006, it burned with low intensity.
Dr McCaw said the severity of the Beechworth fire on Black Saturday was reduced by burns that had been conducted one year, two years and four years previously, that had also provided “anchor points” for fire fighting.
Asked about the effectiveness of small “mosaic” burns that left areas of unburnt vegetation for biodiversity conservation, Dr McCaw said if the primary objective of planned burning was community protection, “you would have to be pursuing fairly high levels of fuel reduction”.