Impact of logging on Black Summer Bushfires disputed

A team of researchers, including senior academics at the Australian National University, have published a rebuttal to a study which analysed the 2019-2020 Australian forest fires.

Its authors, including Professor David Lindenmayer and Dr Chris Taylor, have responded to a study by University of Tasmania's Professor David Bowman, which found climate and weather were key drivers of the bushfires, not logging.

Its authors have argued Professor Bowman's findings were, in fact, consistent with theirs, that bushfires were more severe where logging had taken place.

"They [Bowman] have demonstrated that logging increased the probability of canopy damage by five to 20 per cent," its authors wrote.

Professor Bowman had previously written that the impact of logging on bushfires had been conflated and scientific consensus on its impact did not exist, despite claims to the contrary.

In the recent study, published in Nature Ecology and Evolution, researchers also pointed out what they claim are substantial problems in Bowman's work, warranting further discussion.

According to the authors, Professor Bowman examined canopy damage, sometimes referred to as crown scorch, rather than crown fire.

"For the purposes of their paper and this discussion, we believe that distinguishing between these categories of impact is crucial to quantifying relationships between logging and fire severity," they wrote.

"However, despite the problems in their overall methodology, the data presented in Bowman still show a significant relationship between logging and the probability of canopy damage."

According to Professor Lindenmayer, who is a world leader in ecology and conservation science, logged forests always burn at greater severity than intact forests.

"Logging increases the probability of canopy damage by five to 20 per cent and leads to long term elevated risk of higher severity fire," he said. "On the other hand, if disturbance due to logging is minimised, canopy damage can be reduced, in turn reducing the risk of uncontrollable fires."

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Professor Bowman, who provided expert testimony to both the NSW Bushfire Inquiry and the Australian Government Bushfire Royal Commission, said despite the back and forth, he remains of the view that the impact of forestry was negligible.

"Over the last year there's been the formulation of a response and then our response and now those two responses have finally been published," the Professor in Pyrogeography and Fire Science said.

"We reanalyzed our data in the light of the comments and criticisms of David Lindenmayer and we remain of the view that the fires were driven by extraordinary climate conditions and they burned across a variety of landscapes with different land use histories."

Prodessor Bowman said he disputed the claim their studies had reached the same findings and large areas of forests with no forestry history had burned at high severity.

"To conflate this extraordinary event to the forestry isn't the first thing I would be doing," he said.

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