Adam Morton – October 2, 2010
IT IS not every day you get a chance to make an animal extinct twice. According to scientists, Victoria is steadily working on it.
Leadbeater’s possum, a marsupial endemic to native forest on Melbourne’s fringe, was declared extinct in the 1950s, apparently wiped out by agricultural land-clearing around the Bass River in South Gippsland.
It was rediscovered near Marysville in 1961 – an event considered so momentous it was chosen as one of the state’s two faunal emblems.
Its population peaked at about 8000 in the 1980s, but the last possum in captivity in Victoria died in 2006, and last year’s Black Saturday bushfires devastated its main home in the central highlands, burning 42 per cent of the permanent reserve system in which it lives.
Leading scientists say its survival is now at risk from the state’s forestry industry, particularly the ongoing “salvage logging” operation aimed at maximising timber yields from blackened areas.
Six weeks after Black Saturday, in a report seen by The Age, a US Burned Area Emergency Response team and Victorian bureaucrats advised the Brumby government that extreme care was needed during the salvage logging of large hollow-bearing trees that give the possum its home.
It said: ”It is recommended that none be removed from fire-affected areas known to contain Leadbeater’s possum, powerful and sooty owls, and within Leadbeater’s possum reserves.”
Scientists working in the central highlands claim this advice has not been followed. David Lindenmayer, an Australian National University ecologist who has spent 25 years studying the possum, says that trees are regularly felled in areas important to the survival of Leadbeater’s possum and other threatened species of possum, glider and bird.
While fire can be an effective way of creating the old-tree hollows that the possum thrives in, Professor Lindenmayer says some have been removed – at times through breaches of the Central Highlands Forestry Management Plan, which prohibits logging of pre-1900 trees.
He says the animal is being pushed ”incredibly close to extinction” by the removal of its habitat through a combination of fire and salvage logging, and 40 years of clear-felling of unburnt forest.
”Forestry is the key threatening process,” he says. ”Basically you have a part of the landscape that is non-functional for an animal, and then you add another one and another one. You may reach a stage where the entire landscape is essentially non-functional for animals to live in.
”I really think we need to revisit clear-fell logging of green forest in the central highlands, because after the fire its impact on the possum is being magnified.”
Professor Lindenmayer’s concern is shared by Melbourne Zoo threatened species biologist Dan Harley, who earned a PhD studying a relic population of possums in Yellingbo Conservation Nature Reserve. “Tree hollows suitable for Leadbeater’s take more than 200 years to form,” Dr Harley says.
These claims are vigorously contested by VicForests, the state government forestry agency. It has rejected a claim by environmentalists, formalised in a complaint to the state Ombudsman, that it has illegally logged pre-1900 mountain ash, putting the possum at risk.
Michael Ryan, a VicForests forest scientist, says field surveys are carried out to check for potential Leadbeater’s possum habitat before logging, and an exclusion zone created where necessary. He says there is also ”an extensive conservation reserve system” designed to protect the possum.
VicForests is required by law to leave untouched any three-hectare area with more than 12 hollow trees, and retain four to five trees a hectare in all logged areas. Mr Ryan says clear-felling is used to replicate the natural regeneration process only.
The debate over the impact of salvage logging comes amid a bigger argument about the future of the native forest industry – and whether an impending decision on Tasmania’s forests could put pressure on the Victorian government to consider a similar commitment.
Dr Harley estimates the population of Leadbeater’s possum outside the central highlands would total fewer than 100, restricted to tiny pockets at risk from the next major bushfire.
”We’ve got a second chance, but the possum’s entire distribution is confined to a 70 by 80 kilometre area. We don’t have much margin for error.”