Walking through the wreckage of a bushfire disaster zone, one of the first things you notice is the trees. Those left standing are usually skeletal, stripped naked by wind and blackened by flames. Others lay fallen and shattered on the ground, branches strewn around, their mangled stumps still smouldering.
I saw hundreds, maybe thousands of burned trees in the bushland of southern New South Wales recently, where some of the most devastating bushfires Australia has ever seen swept through just 10 days earlier. And then, after a while, I started noticing something else: not quite trees but the outlines of trees, stark white silhouettes printed like x-rays onto the bone-dry soil.
The strange, arterial shapes were blurrily defined against the charred earth, often with a shallow hole at their root where it seemed the base of a trunk had once been. And they were everywhere: eerily beautiful designs spider webbing across the dirt.
“Tree ghosts,” said the woman who was leading me through the debris. “Aren’t they magnificent?”
In the early hours of New Year’s Eve, a fire front blazed through this area of bushland, incinerating almost everything in its path. Hundreds of hectares of centuries-old native forest were turned to charcoal. And this is what’s left: the skeletons of trees and their pale ghosts.
“What you’re seeing is the ashen remains of trees that have been consumed in fire, either where they’ve fallen or where they were lying,” David Keith, Professor of Botany at the University of NSW, explained over the phone. “Generally what happens after very intense fire events—which this one was in certain areas—is that there’s enough heat for long enough to initiate combustion of all large pieces of wood.”
In the case of the southern NSW bushfires, this “slow combustion” likely took place over the course of a week as the fallen trees were exposed to incredibly high temperatures.
“We’re talking hundreds of degrees celsius, possibly over 1000,” said Professor Keith. “It takes a massive input of energy to get a living tree to burn to the core, right down to ashes... [and] these trees could have been uprooted [in the firestorm] or they could have been standing dead.”
The abundance of tree ghosts throughout large patches of Australian bush speaks to the sheer ferocity of the country’s bushfires. Trees are literally being turned into dust. But as is the case with the fires themselves, Professor Keith suggests that tree ghosts of this calibre are likely the result of several extreme environmental factors—among them: a drier than usual climate.
“The drought we've had that's been more severe in some parts of southeastern Australia, and more prolonged as well, has I think been instrumental in producing this effect,” he said. “What that means is that the fuel has declined in its moisture content to such a degree that that kind of slow combustion fire is possible.
"Certainly there were massive amounts of energy in hot spots within that big fire event. And that's probably what's got it going and produced this unusual effect."
Here are some more photos of "tree ghosts" from an area just north of Bega, NSW.