Forest Logging Increases Risk of Mega Fires

A new study has found that logging can increase the risk of catastrophic wildfires by changing the predominant variety of tree to one that is younger and therefore more prone to fire.

Alpine Ash in Flowerdale, Victoria, after the Black Saturday fires

The study, published in the journal Proceedings of the National Academy of Sciences, saw a team of world renowned ecologists analyse the mountain ash forests of Victoria, Australia, after the devastating 2009 Black Saturday bushfires, as well as decades of ecological data.

Professor David Lindenmayer from The Australian National University Fenner School of Environment and Society and a member of the team, explained that they found that over the past century large areas of mountain ash forests had been logged for timber and pulpwood, creating an area dominated by young fire-prone trees which increased the risk of “mega fires”.

Professor Lindenmayer explains further:

“Before European settlement, the fire regime was dominated by an infrequent severe wildfire that occurred in late summer. Young seedlings germinate from seed released from the crowns of burned mature trees to produce a new even-aged stand.”

“What we are now realising is the combination of wildfire and logging is creating a previously unrecognised landscape trap in which the behaviour of the ash forest landscapes is markedly different from that which would have occurred before European settlement.”

“The core process underlying this landscape trap is a positive feedback loop between fire frequency and severity and a reduction in forest age at the stand and landscape levels caused by logging.”

“Individual patches of logged forest are becoming more fire-prone and when these are taken together the whole landscape is at risk of being consumed by mega fires.”

He added that the increasing dominance of dense young regenerating stands increases the risk of wildfires happening more regularly.

“Detailed on-site measurements following the 2009 wildfires have revealed that young forest burns at higher severity than mature forest, and their analysis suggest we will see more of these severe wildfires in the future.”

“Once a mountain ash forest landscape is dominated by widespread areas of young fire-prone forest, the increased risk for high severity widespread fire decreases the probability that the landscape can return to its former mature state – particularly under the drier and warmer conditions associated with climate change. That’s why it’s described as a landscape trap; it’s self-sustaining.”

Source: The Australian National University
Image Source: Elizabeth Donoghue

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