RESEARCHERS say climate change may be causing a complex stress syndrome in WA's unique biodiverse forests to worsen, as trees across the South-West show signs of declining health.
WA’s Centre of Excellence for Climate Change Woodland and Forest Health are monitoring a complex decline syndrome in marri trees found throughout the South-West of WA. Researchers say many of the trees are showing signs of stress due to environmental factors, including fungal disease and pests and severe cold temperatures.
Director Giles Hardy says that while the decline syndrome is not completely understood, researchers suspect climate change has contributed to the problem.
“With the decrease in rainfall, we also see an increase in transpiration, so many of our woodland species are under immense stress. With stress, they will be open much more to attack by insects and opportunistic pathogens that take advantage of the tree’s poor health, he says.
“Marri trees (Corymbia calophylla) are a good example of that. I receive reports once a week of marri trees in urban areas with massive cankers, caused by an endemic pathogen (Quambalaria coyrecup). So the question becomes, why is this pathogen that has always been around starting to kill trees – a drying climate is probably a reason for that."
Researchers consider the marri a ‘keystone species’, providing food and habitat for various other flora and fauna, including Carnaby's Black Cockatoo (Calyptorhynchus latirostris). They warn further damage to the trees could have dramatic impacts on WA ecosystems.
“These tree species support a range of life for which we simply don't understand yet what the flow on effects could be,” Prof Hardy says.
Prof Hardy says the evidence supporting increasing temperatures in WA’s climate is “quite compelling”, urging the science community to move beyond debating the reality of climate change and begin preparing for its consequences.
He says climate modelling for WA predicts the South-West to get hotter and drier, with some estimates predicting a 20 per cent decrease in rainfall by 2030.
“We have certainly become about 20 per cent drier in the last 30 years – that evidence is clear – and I believe there is enough evidence now to say it is time to develop strategies to confront the problem."
“We should be starting to conduct research to adapt to the changes, and develop strategies that will help sustain our [ecosystems] in a drying climate. We are starting to see some very severe declines which link to climate change”, he says.
The centre is proposing a large-scale research project establishing monitoring plots throughout the South-West region to determine the causes of marri decline and developing long-term, sustainable solutions.