A study of 25,000 trees could show how rainforests will respond to a warming climate, researchers say.
University of Queensland PhD candidate Julian Radford-Smith has spent the past two years studying the wood density, leaf size, height and other “traits” of more than 300 tree species between Ballina and Gladstone.
He said these traits illustrated how the trees “use light and water” to “survive and thrive” in subtropical rainforests depending on climate.
His PhD supervisor, Associate Professor John Dwyer, said the research told us why trees grow where they do.
“It can inform what might happen to these species under climate change,”
Dr Dwyer said.
“We can go — if the climate is going to change, where do we expect these species to grow? Not just based on some association that dry things grow in dry places and wet things grow in wet places.”
Covering new ground
At night, Mr Radford-Smith would pour over topographical maps of Queensland and northern New South Wales looking for the perfect site.
“Even if it meant hiking for a day to get to these sites, it didn’t matter,” he said.
In some cases, there were no tracks, with Mr Radford-Smith scrapping through dense bush or scrambling up rocky inclines.
They kept a light load, bringing just tapes to measure out the plots, and large calipers to measure the diameter of trunks.
Once on site, they laid out multiple 25 x 25-metre plots in more than 45 locations, painstakingly identifying trees, measuring their size and placing branch and leaf samples in a solar powered fridge.
It was tough but rewarding work, Mr Radford-Smith said, often starting at dawn and finishing once light was too low to identify species.
On trips he was joined by Dr Dwyer or an assistant, collecting samples of wood density and leafs to bring back to a lab in Brisbane.
On one trip to Mount Coulson, about 60 kilometres south of Gladstone, Dr Radford-Smith noticed a tree with smooth, “salmon-tinged” bark and bright pink new growth.
The tree — a Backhousia, the same genus as lemon myrtle — has been confirmed by the Queensland Herbarium as an “undescribed species”.
He said going to areas where very few people, let alone botanists, had been over the past century was a special experience.
“It was almost a treasure hunt for me to go to these unknown locations and set up my plots,” he said.
Under appreciated forests at risk
Dr Dwyer said while there was public understanding and appreciation of some of the region’s wetter rainforests, lesser known but equally important forests are at risk.
He said dry rainforests — which he called “the Australian oxymoron” — have been heavily affected by logging, invasive weeds and cattle grazing.
However some remain in excellent condition such as in Nangur National Park, north of Goomeri.
These under appreciated parks really are “very special places that very few people are even aware of”, he said.
Dr Dwyer said the research was important as it gave scientists a better understanding of “how trees earn a living in their respective environments,” no matter how much public interest there was in the area.
“We can link the strategies of trees to where they have occurred,” Dr Dwyer said.
