09/06/2020

(AU) Logging And Fire Both Make Forests More Flammable

Sydney Morning Herald - Jamie Kirkpatrick*

The clear and overwhelming evidence is that logging makes forests more flammable.

 These are the findings of four peer-reviewed, published scientific studies from four institutions in six years, and of multiple scientific reviews.

Bushfire risks have been getting worse for eastern Australia in recent decades. Credit: NIne

The likely reasons are that after logging, increased sunlight dries out the forest floor, thousands of fast-growing saplings per hectare increases the fuel for a fire to burn, and the wind speed on hot days increases because of the lack of a tree canopy (wind speed is a key factor in creating extreme fire conditions).

Most branches that burn in a bushfire are smaller than the diameter of a human thumb. Young trees burn almost completely while big, tall trees often remain alive and standing after fire.

Climate change is already resulting in more extreme fire danger days, and the evidence is that native forest logging makes things worse.

Dense plants create a "fuel ladder" to the treetops. Dense plant growth occurs in forests growing back from either logging or fire. More severe fires produce denser regrowth. Growing trees in young forests create greater fire hazard for decades.

In logged forests, the body of evidence shows increased flammability begins in the first 10 years after logging or fire and continues for about another 30 years, depending on forest type.

The evidence is that logging and fire both make forests more flammable. Post-fire, the logging industry receives taxpayer-funded grants for additional, increased logging of burned forest, as it did last month. Peer-reviewed studies show post-fire logging also increases forest flammability for decades.

After logging, the top of the tree, the bark and the branches are left on the ground. Only the stripped trunk of the log is taken. Even if the area is then burned, excess dead branches remain, and then dense plant regrowth creates much more fire fuel.

An examination of Tasmania’s January 2019 fires found forests growing back after industrial logging burned more severely than old-growth forests.

 Another peer-reviewed paper found Victorian state forests allocated for logging burned more extensively and frequently than national parks over the past 20 years, and 28 per cent of the area VicForests had planned to log up until 2024 was burned last summer.

Two other studies found fire is more severe in logging regrowth. Studies from the US and Patagonia had similar outcomes.

The catastrophic Kilmore fire in Victoria in 2009 burned slower and with less intensity in tall, wet, old-growth forest on Mt Disappointment.

The logging industry funded a contradictory piece on fire behaviour in 2014, using members of a group called the Institute of Foresters of Australia. The paper, led by Peter Attiwill with co-authors employed by the logging industry, was titled Timber harvesting does not increase fire risks and severity in wet forests of southern Australia.

Immediately, a peer-reviewed paper called Errors by Attiwill (Bradstock and Price, 2014) responded that Attiwill had “erroneously reported our results” and pointed out other key flaws.

Speaking about mountain ash forests, Attiwill had said: “There is no evidence from recent megafires in Victoria that younger regrowth (less than 10 years) burnt with greater severity than older forest (over 70 years)”, a statement that did not address the key period of flammability found by other studies, between around years 10 and 40.

Robust analysis of the same Victorian fires shows a clear relationship between time since logging and fire severity.

There is no published scientific work suggesting logging reduces fire risk. Still, VicForests aggressively attacks scientists who publish peer-reviewed science on the subject, including those it has previously employed.

Private Forests Tasmania has claimed commercial logging is a preventative fire strategy. This claim is not supported by any peer-reviewed fire behaviour models.

Industrial logging continues near country towns including Warburton, Toolangi, Healesville, Noojee, Orbost, Mallacoota and Cann River in Victoria; around Eden and Batemans Bay and along the south and north coasts of NSW, and in areas around Geeveston, Maydena, Derby, Southport and Dover in Tasmania.

As scientists, our purpose is to inform the public and decision-makers about the peer-reviewed scientific evidence. The evidence is that logging makes forest more flammable.

*Jamie Kirkpatrick is distinguished professor in geography and spatial sciences at the University of Tasmania. This article was co-authored by Dr Jennifer Sanger, Dr Chris Taylor, Dr Robert Kooyman, Dr Phil Zylstra and Professor James Watson.

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