Give a Possum a Tree

New Matilda

YOU know an animal is in serious trouble when you start counting its habitat trees individually. David Blair, a member of the Australian National University team monitoring the federally endangered Leadbeater’s Possum, stands on a dirt track in gumboots and a green vest, pointing out old grey eucalypts one by one. “Probably 14,” he says when he’s finished counting.

Believe it or not, 14 trees is a reasonably high number. We’re in Toolangi State Forest, and Blair is leading us through prime Leadbeater’s Possum habitat. The species, one of Victoria’s emblems, is virtually confined to a 70km by 80km area about two hours drive north-east of Melbourne. The animal was thought extinct until it was rediscovered here in 1961, and it could disappear again.

Victoria’s 2009 Black Saturday bushfires burned 42 per cent of the animal’s permanent reserve system and there could be as few as 1000 possums left. “They’re on the edge of extinction, particularly after the big fires,” says Sera Blair from Friends of Leadbeater’s Possum Inc.

The animal certainly looks vulnerable. This elusive nocturnal marsupial weighs less than 170 grams, with grey fur, a club-shaped tail, tiny paws and wide round eyes. Sightings are rare, so habitat is the main clue as to how many possums are left and where they live. Habitat also determines which areas of the forest are protected and which are not. To understand why the Leadbeater’s Possum is in danger you need to crunch through the undergrowth and see its home for yourself.

The possum prefers to live in short, thick, partially decayed eucalypts at least two centuries old. Ecologists who work with the animal refer to these trees as “stags”. Blair points out stags on both sides of the track but explains that only the forest on the right side is protected. The forest on the left is a logging coupe named “South Col” marked for clearfelling in August.

Blair explains that the ANU has five monitoring sites nearby, including one about a kilometre and a half away. “There’s Leadbeater’s that have been recorded within cooee of here,” says Blair. “Some of those have burnt now, which potentially makes this site even more important.”

The Leadbeater’s Possum has evolved to cope with wildfire, but several massive infernos over the last century have left a young forest (pdf) with few live hollow-bearing trees.  When the Black Saturday fires swept through the area, they skipped parts of Toolangi State Forest, leaving a green tuft in a blackened landscape. “Now they’re logging the crap out of the green patch in the middle,” says Blair.

Old, hollow-bearing trees aren’t harvested for timber, but those left standing after clearfelling are exposed to the elements and prone to collapse. Old trees can also be lost in the high-intensity fire used to regenerate a logged area. The forest that grows back is of a single age — with fewer hollow-bearing trees than before.

ANU ecologist David Lindenmayer has estimated about 80 per cent of the possum’s range is in designated logging areas (VicForests claims only 50 per cent). Within these areas, the possum is isolated to patches of suitable habitat, but environmental organisations claim even those are being logged. Sarah Rees, director of green group My Environment, says this coupe is a prime example. Her organisation conducted an ecological survey, with consulting from Acacia Environmental Management, which found the coupe has 75 hollow-bearing trees in clusters that should qualify it as a Leadbeater’s Possum habitat. Young ash forest with 12 or more live hollow-bearing trees per three hectares is classed (pdf) “Zone 1A” and set aside for wildlife conservation.

Yet VicForests has included the coupe in its latest Timber Release Plan (pdf), which outlines timber harvesting in the central highlands until 2016. Local environmentalists are outraged. “This is a no-go zone, as far as we’re concerned,” says Rees. “If we have to lock onto bulldozers to protect this area, there’s a number of us that’ll do it.”

Luke Chamberlain, the Wilderness Society’s Victorian forests campaigner, tells New Matilda that this coupe is representative of a broader problem. “It’s a prime example that VicForests has no idea what it’s destroying and shows no care to what it’s destroying.”

It all comes down to habitat. Who assesses it, and how? Then there are the cumulative effects of logging: If Victoria’s central highlands area is harvested on a 70-year rotation, how will the trees ever grow old enough to become suitable habitat for the possum? Finally there’s the most important question of all: After decades of logging and the recent devastating bushfires, how much Leadbeater’s Possum habitat is actually left?

Michael Ryan, a VicForests forest scientist, says pre-harvest surveys are conducted for potential Leadbeater’s habitat. In the South Col coupe, for example, Ryan has identified areas that are “getting close” to Zone 1A habitat. Any old hollow-bearing trees that meet the criteria will be reserved, he says. VicForests is also considering “variable retention harvesting” in the coupe, a form of logging in which patches of habitat are preserved for the future.

But Ryan acknowledges individual retained trees “don’t always survive the regeneration burn” after clearfelling and dead stags “are very hard to keep standing because they catch fire”. He also concedes that the forest that grows back has fewer hollow-bearing trees, but argues the possum’s best habitat is already included in the permanent reserve system. In June 2008 another 30,000 hectares were added to help protect the species.

At the moment, no one can tell New Matilda exactly how much Leadbeater’s Possum habitat is left. What’s certain is that there is very little old growth where the animal lives — a senior director from the Victorian Department of Sustainability and Environment recently estimated only 2000 hectares of unburnt and unlogged mountain ash forest remains in the central highlands. Yet this isn’t an accurate gauge of habitat because Leadbeater’s Possums can also live in young forests with clusters of old trees.

Whatever the case, the leading experts on the animal are worried. ANU ecologist Professor David Lindenmayer, who has spent 25 years studying the possum, recently stated that the species is “incredibly close to extinction” and if current logging practices continue it won’t last the next 50 years.

Ultimately, the Leadbeater’s Possum is only the focus of media attention because it’s a “flagship” species: a cute, furry figurehead for a forest in crisis. What’s really at stake are those old, hollow-bearing trees that provide habitat for many different animals, not just one lucky enough to be named a state emblem.

Back in Toolangi state forest, Blair leans against the dusty panels of his white ute and stares into the bush. The South Col coupe (pdf) is small, only 32 hectares. Why bother fighting for it? “We simply just don’t have many big old trees left in these forests,” he answers, crossing his arms. “There’s so little old growth — and we’re now talking individual trees — that we really, really need to conserve every single one of them. Because you just can’t replace them anytime soon.”