A mysterious plague is killing our snow gums in the Snowy Mountains

Jozef Meyer checks a light trap in Kosciuszko National Park. Picture: Kate Matthews.
Jozef Meyer checks a light trap in Kosciuszko National Park. Picture: Kate Matthews.

Jozef Meyer reaches into a black perspex cone. "I've got a phoracantha!" he says excitedly as he withdraws a small, coffee coloured beetle and shows it to me. It's about three centimetres long with tortoise shell markings on its back. It's flat like a cockroach and has long, swooping antennae the length of its body.

We're in a stand of snow gums in the Perisher Valley checking Jozef's traps. The group of trees looks healthy. But then you look up, and see the dead branches poking through the thinning canopy. Jozef says all these trees are doomed.

"There are great examples of trees I saw a year ago in December and I thought 'oh, yeah, it's in the pretty early stages, it should be okay.' And then this year, it's just completely gone," he tells me.

Jozef is an honours student studying environment and sustainability at the Australian National University. He's staying in the Perisher Valley in Kosciuszko National Park while he investigates the beetle believed to be causing dieback in the snow gums - the phoracantha or longicorn beetle.

On almost every tree here, just above the last of the Smiggin Holes lodges, there's evidence of the phoracantha beetle. I can see a small hole with an ooze of sawdust -- or "frass" -- trickling out the side. It means there's beetle larvae working away on the trunk just underneath the bark.

Jozef tells me you can see little puffs of sawdust coming from the trunk. Many of the trees have thick piles of sawdust at their bases. The beetle is killing them across the high country - an area which stretches from Namadgi in the ACT to the Alpine National Park in Victoria - and no one knows why.

Dr Matthew Brookhouse, a lecturer at the ANU's Fenner School of Environment and Society, first noticed dieback in snow gums a few years ago. He went up to Perisher Valley to investigate reports of localised dieback of snow gums.

A phoracantha beetle of the type scientists believe is killing the snow gums throughout the Australian Alps. Picture: Kate Matthews

A phoracantha beetle of the type scientists believe is killing the snow gums throughout the Australian Alps. Picture: Kate Matthews

"When we arrived in Perisher, the scene was shocking. What I saw there was not just one or two trees dying, but a good portion of the main valley in Perisher was in decline," he tells me in his office in Canberra.

He then spent some time travelling around the Snowy Mountains, trying to figure out what was going on.

"It became evident to me very quickly that we had quite a substantial, very widespread and in some cases very, very severe dieback event playing out across the mountains," he says.

Dr Matthew Brookhouse is leading the charge against a wood boring beetle responsible for killing snow gums throughout its range - from Namadgi in the ACT to the Alpine National Park in Victoria. Picture: Sitthixay Ditthavong

Dr Matthew Brookhouse is leading the charge against a wood boring beetle responsible for killing snow gums throughout its range - from Namadgi in the ACT to the Alpine National Park in Victoria. Picture: Sitthixay Ditthavong

Dieback is occurring throughout Australia for a variety of reasons and to different degrees. The alpine region suffered a recent catastrophic dieback event on the Monaro High Plains. Hundreds of thousands of ribbon gums in an area roughly the size of the ACT were killed over a 15-year period.

If you drive from Cooma to Jindabyne you can see a seemingly endless number of gum trees, some centuries old when they died, standing grey and lifeless along the road. In the Monaro it was a different native insect killing the trees. Something had changed, scientists still don't know what, and the eucalypts were suddenly unable to defend themselves. The ribbon gum was the dominant tree in that landscape and now they're almost all gone.

"People have said, well, that dieback process has ended. Well, that's true. That dieback process has ended. Because everything is dead," says Dr Brookhouse.

Picture: Kate Matthews

Picture: Kate Matthews

A variation of what happened on the Monaro now seems to be happening higher up the slopes. The snow gum is the only tree which lives above 1600 metres and they're being wiped out with no obvious way to save them.

People I spoke to hope there's lessons from the earlier dieback which can help to save the snow gum.

Michelle Francis is a Ngarigo elder local to the Snowy Mountains area. Ngarigo custodians have lived in the Australian Alps for thousands of years, although many were dispersed by colonial violence.

"From a cultural perspective it's very emotional, because it affects our whole ecosystem. Every plant has a job to do. So when one's removed, what's next?," says Michelle.

Michelle and I drive out to an area of the Monaro affected by dieback. We're barely 20 minutes from Jindy when grey, lifeless eucalypts start popping up along the highway.

Michelle Francis is a Ngarigo elder local to the area. She first noticed changes in the ribbon gums on the Monaro Plain after the 2003 bushfires. Picture: Tom Melville

Michelle Francis is a Ngarigo elder local to the area. She first noticed changes in the ribbon gums on the Monaro Plain after the 2003 bushfires. Picture: Tom Melville

"It's very sad to drive to Kunama Namadgi [Mount Kosciuszko] and to see that, and not see people jumping out of their cars and saying 'what's going on with the habitat, what's going on with our environment?'" Michelle tells me.

Dr Brookhouse says he's continually surprised he's breaking new ground in his research on snow gums, and that despite the annual rush of tourists to the Australian alps, no one seems to notice.

"It's a terrible thing because these forests are slipping away in front of people's faces. And they simply can't see it," he says.

A dead snow gum showing clear evidence of the phoracantha beetle's damage. Picture: Kate Matthews

A dead snow gum showing clear evidence of the phoracantha beetle's damage. Picture: Kate Matthews

Michelle says more needs to be done to protect Kosciuszko National Park if it is going to continue as a unique ecosystem and as a tourist attraction.

"The trees are screaming 'What are you going to do about this? How are you going to save us? And how are you going to bring life back into the park?'" She says.

Michelle and her family first noticed something was wrong with the Monaro ribbon gums after the 2003 bushfires, which burnt from Victoria, through NSW and into the ACT. The trees were weakened, vulnerable.

Overgrazing, drought stress, fire damage, and climate change have all been touted as possible culprits for dieback of snow gums, higher up, in the Snowy Mountains.

Insect traps in the Perisher Valley. Jozef Meyer is trying to understand more about the phoracantha beetle's behaviour. Picture: Kate Matthews

Insect traps in the Perisher Valley. Jozef Meyer is trying to understand more about the phoracantha beetle's behaviour. Picture: Kate Matthews

Matt Brookhouse believes the wood borers are feeding on trees which are already sick. The next question is, how do you stop it?

If a tree in a backyard had a beetle infestation, you could treat it - an arborist armed with readily available pesticides would do the trick. That won't work on the level of an ecosystem. What would a chemical do if you were to disperse it over the entire high-plains environment?

Dr Brookhouse is desperate to find out as much as he can to help develop the tools to save the snow gums.

"What happens if there is no way we can slow the insects as they gradually move across the landscape? What are we left with? Are we left with the scenario that played out in the Monaro? That, yes, the outbreak ends, but it ends because there's nothing left for the insects to eat. And it's difficult not to be affected by that," Dr Brookhouse says.

Jozef Meyer points out dieback affected trees in Kosciuszko National Park. Picture: Kate Matthews

Jozef Meyer points out dieback affected trees in Kosciuszko National Park. Picture: Kate Matthews

The snow gum is the only tree that can survive in the sensitive, alpine environment above 1600 metres. Dr Brookhouse believes its loss would be catastrophic, and have flow-on effects throughout an environment that covers NSW, the ACT and Victoria.

"You have to think about the kind of loss associated with the loss of the Great Barrier Reef. The coral that builds the reef is alive, but the attendant fish and other species depend upon that structure. There would be substantial cascading ecological losses," he tells me.

Back at Perisher, Jozef is working hard, studying the offending beetles. If he can understand why the bug chooses this tree or that one then he can help protect the snow gums. It's not clear yet why the hungry bugs are attacking those venerable trees which live in Australia's high country. These aren't young trees, some are hundreds of years old, they've survived droughts, fires, and anthropogenic impacts.

"It can kind of be a bit alarming to think about. If no one does anything, and no one even cares, then where we end up is no trees from Rennix Gap to Charlottes Pass. Just nothing," Jozef says.

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This story What's killing the snow gums? first appeared on Newcastle Herald.