by A few weeks ago, Joe Fontaine stood in the middle of one of Western Australia’s eucalyptus forests on another hot and dry day stripped of the absurd backing of bird calls.
“I would hear this scraping-grain noise coming from the trees,” says Fontaine, a forest ecologist at Perth’s Murdoch University.
Peeling back the bark, a handful of beetle larvae “about the size of a penny” were feeding on dead wood and dying. “When the trees are stressed, the beetles get the upper hand on the tree,” he says.
Above Fontaine, the forest canopy was turning brown. Trees that are more than a hundred years old are hardly alive. Some of these giant jarrahs may survive, but others will not.
It’s a scene being replicated in forests and coastal bush that stretches more than 1,000km (620 miles) across the state’s south-west after drought and baking heat.
Eucalyptus trees such as jarrah and marri dominate many of these ecosystems, and coastal shrubs are scattered along the banks, the likes of which are found nowhere else in the world.
There are pictures of dead and dying bushes and trees in Fontaine’s inbox. One of the earliest signs came in February when Perth’s street trees began to die after a number of days above 40C. The city had its driest six months – from October to March – since records began.
There were similar scenes in the state’s southwest eucalypt forests in 2010 and 2011 – a die-back event that prompted more than a dozen studies. Fire struck the drought-stricken forests years later, releasing carbon dioxide, and raising concerns that the forests could turn into a source, rather than a store, of carbon.
Dr Katinka Ruthrof, a senior research scientist in the state government’s Department of Biodiversity, Conservation and Attractions, says the current die-off has similar characteristics to the 2011 event. The department is assessing the damage by using from images from satellites, fixed-wing aircraft and drones, as well as field checks.
“Some plants may be able to survive and resprout when conditions improve, but many may die,” she says. “This depends on how long the dry season lasts.”
Ruthrof says changes in habitat structure and composition would affect several species, including the provision of habitat and food resources for wildlife.
Dr Mark Harvey, curator of spiders, millipedes and centipedes at the Western Australian Museum, says hundreds of invertebrate species in the south-west are found nowhere else.
“The south-west corner of Western Australia has been isolated from other parts of the continent for the past three million years. That allows species to evolve on their own.”
Those species have been used to humid conditions for thousands of years, he says.
“We are very concerned about this drying event. If the animals don’t have a coping mechanism like a udder to escape the heat, they literally die.
“They have disappeared locally. They have nowhere to go. Recolonization will take thousands of years, even if the habitat has recovered. The prognosis is not good.”
Fontaine says it is “disturbing” to see the death of the bush and forests and he is concerned about the wildlife.
“I’m going to hell with leather now to get people to work ‘oh shit, we’ve got to document this’,” he says.
A clear climate signal
Murdoch Fontaine’s University colleague, atmospheric scientist Dr Kerryn Hawke, says the region’s trees and plants are used to a Mediterranean-style climate with cold fronts from the southern ocean bringing good rain in winter.
But studies have shown that these fronts are shifting further south, offshore.
She says: “These areas don’t reach as far north anymore, which means we’re seeing less initial rain and, when it does reach us, it’s less intense. And we are seeing more and more very hot days due to climate change. The vegetation is not used with such low rainfall.”
Over the past 12 months, rainfall has been well below average in much of the west of the state and the lowest on record in some places, while temperatures have been the highest on record.
“It’s a perfect storm of temperature and rain. But what stood out was the heat we had very early on,” she says, referring to heat waves in September and November.
The conditions in recent months are part of a particular drought that scientists have seen in the region since the 1970s.
Compared to the period from 1901 to 1960, cool season rainfall has fallen by 20% over the past twenty years. Very wet years have almost completely disappeared.
About half of this change has been blamed on rising greenhouse gas emissions, which may be an underestimate, according to one study led by Bureau of Meteorology scientists.
Even with rapid reductions in greenhouse gas emissions, the study suggested, the drying trend is likely to continue for the rest of this century.
Dr Michael Grose, a climate scientist at the Australian government’s Commonwealth Scientific and Industrial Research Organisation, says as early as the 1970s scientists were seeing a drying trend.
“It’s one of the clearest and strongest signals of average rainfall anywhere in the world,” he says.
Fire and fear
There seems little relief in sight, with forecasts for the next three months pointing to more hot and dry weather to come.
Fontaine says with so much dead vegetation around, the risk of bushfires is rising.
Fire authorities need to be careful, he says, when conducting prescribed burns to try to reduce the risk of larger, out-of-control fires.
About 430km south-east of Perth is Walpole, where David Edmonds has a beef and orchid farm and volunteers with the Walpole-Nornalup National Parks Association.
He grew up in Walpole and this year parts of the desert region – including giant 90-metre carrion trees – are turning brown.
“The rain stopped really early. The death is becoming very clear on the granite outcrops,” he says.
“It’s sad. You worry if this is a one-off or something that will become more common. We can’t start watering the trees.”
