Modelling says there is a 92% chance mountain ash forests will not be able to support current ecosystem by 2067

This article is more than 2 years old

This article is more than 2 years old

Decades of unsustainable logging has created an “extinction debt” in Victoria’s central highlands that will trigger an ecosystem-wide collapse within 50 years without urgent intervention from the state government, ecologists have warned.

According to modelling produced by Australian National University researchers Dr Emma Burns and Prof David Lindenmayer, there is a 92% chance the mountain ash forests will not be able to support its current ecosystem of arboreal animals, like the critically endangered leadbeater’s possum, by 2067.

If current logging practices continue, or if the forests experience another Black Saturday level bushfire, the likelihood of collapse approaches 100%.

“Anything in the next 50 years that requires a tree old enough to bear a hollow is in trouble,” Burns said.

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The modelling, published in Austral Ecology, has been before the Andrews government for two years but is yet to receive a formal response. The expert panel tasked with resolving the future of the central highlands declared itself unable to come to agreement and disbanded in February.

Guardian Australia understands it is one of the top three issues the premier, Daniel Andrews, wants resolved before the 2018 state election. If unresolved Labor stands to lose votes from both sides, with the Greens pushing for the area to be protected under a new great forests national park and the Liberal and National parties calling for more areas to be opened up to logging.

Burns said the problem is the product of historical logging practices and that no amount of future logging is compatible with the ecosystem’s survival.

“Unsustainable practices in the past is what’s causing problems for the current logging industry, which is now much more sustainable, but they have got this extinction debt,” Burns told Guardian Australia. “My opinion is there is nothing they can do sustainably to harvest that 52,000ha area of concern.”

Burns presented the modelling at a joint conference of the Australian and New Zealand ecological societies in the Hunter Valley on Thursday. She said it had the potential to become a significant election issue.

The modelling was undertaken as part of an IUCN assessment and saw the ecosystem listed as critically endangered on the IUCN red list.

It was also relied upon by the commonwealth threatened species scientific advisory committee to increase the listing of the leadbeater’s possum from endangered to critically endangered.

That decision has been challenged by the forestry industry and is due to be reviewed by the committee, which has provided survey data showing an increase in known leadbeater’s possum populations and called for the species to be downlisted to endangered or lower.

In March, the then Nationals leader, Barnaby Joyce, called for the possum to be taken off the endangered list to boost logging and support rural communities.

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The committee is due to review that application next month, with the minister expected to announce his decision by March.

Conservationists have said the survey data was evidence of increased monitoring but not an increase in population.

She has called for a combination of widespread forest protections and direct interventions, such as placing nesting boxes.

“If we were really interested in protecting the diversity of that system we would be really interested in protecting 1939 regrowth, which is not what we do,” she said. “We protect the old trees with the hollows but we need to be protecting the regrowth that’s coming on stream. It’s like we’re protecting the grandparents but the middle population that you would need to replace yourself is being wiped out.”

Mountain ash trees that grew following the 1939 Black Friday bushfires are not yet old enough to bear hollows but are the right age to be logged.

“We should protect 1939 regrowth,” Burns said. “The implications of that is that it wouldn’t be a viable logging industry, economically … that has implications and needs to be thought through very carefully because that is people’s livelihoods.”