This article is more than 3 years old

This article is more than 3 years old

A proposal to release areas of protected Victorian old-growth forest for logging is “environmental vandalism crossed with bad economics” that would put a number of vulnerable species at risk of extinction, a leading Leadbeater’s possum expert has said.

Professor David Lindenmayer, from the Australian National University, is recognised as the world expert in the critically endangered Leadbeater’s possum.

He said a proposal by the Nationals leader, Barnaby Joyce, to downgrade the threatened species rating of the animal and allow logging in areas of state forest that currently form part of the conservation reserve was “madness” and showed a lack of scientific understanding.

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In a letter to the Victorian premier, Daniel Andrews, on Sunday Joyce suggested the threatened species status of the possum should be reviewed in response to an increase in the number of confirmed sightings of the animal.

But Lindenmayer, whose research guided the survey effort, said they had not discovered any new populations or an increase in numbers, just confirmed populations they already knew to exist.

“We probably still have significantly fewer animals than there are giant pandas,” he told Guardian Australia. “Logging the animal’s habitat is not going to do anything other than drive the animal to extinction … This is basic biology 101 that you would teach to first years, and I know that because I have.”

He said there was “no chance” the threatened species scientific committee, which advises environment minister Josh Frydenberg on threatened species listings, would downgrade the species. “They base their assessment on this thing called ‘science’ and ‘evidence’, which is not what Barnaby Joyce does,” he said.

Frydenberg said on Monday he was “open to asking his expert advisory committee to assess the conservation status of species when new information becomes available,” but was unable to make unilateral changes.

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Of the 195,000ha of remaining alpine mountain ash forests, just over half, or 98,500ha, is currently protected in a formal reserve. Of that protected area, 58% is state forest designated a special protection zone, the area Joyce suggested could be opened to logging.

Additional logging areas are needed, Joyce said, because the Victorian government has protected an additional 43,000ha of the forestry estate, prompting it to reduce by half the quota of sawlogs available to Heyfield sawmill operator Australian Sustainable Hardwood.

The company announced it would close the sawmill after being unable to negotiate a higher sawmill quota with the Andrews government. That will cost Heyfield, a town with a population of just over 2,000 people that has historically relied on forestry as its major industry, about 250 direct jobs.

Lindenmayer said increasing the sawlog quota would not ensure the long-term sustainability of the Heyfield mill but would destroy the chances of long-term survivability of the Leadbeater’s possum.

“Victorian government’s own work … shows that if you want to conserve Leadbeater’s possum, you basically have to protect almost all of the remaining mountain ash forest,” he said. “When we’ve done the analysis of the ecosystem itself, the mountain ash ecosystem comes out as critically endangered.”

Population modelling published by Lindenmayer, Victorian government scientist Charles Todd, and others last year found the existing reserve network in Victoria’s central highlands was “not adequate” to ensure the long-term survivability of the Leadbeater’s possum, measured as ensuring a population of at least 500 females persists in 40 generations time.

That would test the viability of the reserve network out to 200 years – the same amount of time it takes for a mountain ash tree to grow and mature to the point where it develops large hollows and is a suitable habitat for Leadbeater’s possums.

Other vulnerable species that share the mountain ash forests, such as the Great glider (Petauroides volans), Yellow-bellied glider (Petaurus australis), and Sooty owl (Tyto tenebri-cosa), are also at risk from increased logging.

“These different species are lining up in terms of showing us that the system itself is in huge trouble,” Lindenmayer said.

He argued that the economic return from tourism was higher than the return from logging. “If you were to follow Malcolm Turnbull’s mantra of jobs and growth, you would not do what you’re doing now. You would truly innovate and invest in eco tourism.”

Professor Michael McCarthy, from the University of Melbourne, said aside from their biodiversity value, mountain ash forests also played a crucial role in ensuring Melbourne’s clean water supply.

“A large proportion of Melbourne’s water supply comes from rain that fell on mountain ash forests,” he said. “The forest itself helps provide good quality water.”