20 Apr 2014

Peat Bushfire Causes Irreversible Changes

From the Mercury.
It was a devastating blaze that ignited on January 4 last year in Tasmania’s tinder-dry south from which the environment is still recovering.
But unlike the well-documented Forcett-Dunalley fires, which were sparked on the same day of record heat, the Gilbin River fire has until now gone largely unnoticed by the Tasmanian community.
The blaze turned 44,000 hectares of the state’s south-west wilderness into a charred moonscape.
While the houses in the Tasman Peninsula region can be rebuilt, scientists are worried that the intensity and longevity of the south-west “megafire” may have damaged the region’s fragile ecology forever.

A fire expert from the University of Tasmania’s School of Biological Sciences, Dr David Bowman, who is leading a team of scientists studying the long-term effects of the blaze, said the nightmare scenario was of a region unable to regenerate its soils and vegetation.
He described the Gilbin River blaze, which may have been sparked by an illegal fire or a lightning strike, as the fire every Tasmanian should know about.
“I’m a fire ecologist, and I’m seeing something that is a once-in-a-generation event. To see fires of this intensity and this scale, I wasn’t psychologically prepared for it,” Dr Bowman said of his first visit to the area.
“South-west Tasmania is a flammable environment but the key point about it is that it’s got organic soils which are just this side of brown coal. When you dry it out, you can burn it.
“We know from previous work that it takes thousands of years for these peat soils to accumulate and burning them back to bedrock is going to have a long-term effect.
“One scenario is that we are possibly going into what is called state-shift where we switch from a vegetated, green south-west Tasmania with peat soil to a de-vegetated, rocky and skeletal environment. It could become a curious place – a high-rainfall desert.”
Dr Bowman said such a scenario was just a hypothesis at this stage and it might turn out that past fires had had a similar effect and the vegetation was able to recover easily but that it was essential scientists found out.
But he said that in terms of climate-change vulnerability, the south-west wilderness was similar to the Great Barrier Reef, a precariously balanced ecological system where changes could be expected to easily emerge.
“The research question is: Are we seeing these changes here? I can’t tell you,” Dr Bowman said. “But this hypothesis is the scary idea.” Less scary was the notion that systems could recover over time and build up organic soils.

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