SOURCE: The Guardian
DATE: March 6, 2019
SNIP: Australia’s forests are being reshaped by climate change as droughts, heatwaves, rising temperatures and bushfires drive ecosystems towards collapse, ecologists have told Guardian Australia. Trees are dying, canopies are getting thinner and the rate that plants produce seeds is falling. Ecologists have long predicted that climate change would have major consequences for Australia’s forests. Now they believe those impacts are unfolding.
“The whole thing is unravelling,” says Prof David Bowman, who studies the impacts of climate change and fire on trees at the University of Tasmania. “Most people have no idea that it’s even happening. The system is trying to tell you that if you don’t pay attention then the whole thing will implode. We have to get a grip on climate change.”
Dr Joe Fontaine, an ecologist at Murdoch University, says forests across Australia are changing. “Impacts are direct – trees dying from heat and drought – as well as indirect – more fire, fewer seeds and a raft of associated feedbacks.”
A study of the impacts of a heatwave in 2010 and 2011 in the south-west that followed long-term drops in rainfall found that the the large jarrah eucalypts and the area’s giant banksias were severely affected. A knock-on effect, another study found, was that the area became even more prone to fires.
Bowman and colleagues have found that big eucalypts grow slower as temperatures rise and alpine ash forests are at risk of being wiped out because fires are coming along too often.
Bowman says the idea that Australia’s forests are well adapted to the country’s variable climate and can withstand fire and drought, is incorrect. “A big misapprehension is that these things are climatologically flexible, but they’re just not,” he says, explaining that Australia’s dominant eucalypts have “fine-tuned their life history around assumptions of fire frequency”, but “climate change is just blowing that up”.
“All this is non-linear,” he says. “What will happen is the system will crash faster than we realise. Yes, it will reassemble and there will be forests, but they won’t look anything like what we have now. We are going to see this transformation before our eyes.”