Turning Up The Heat To Push Many Australian Plants To The Brink, New Study Finds

Fairfax - Peter Hannam

Australia's inland plants are among those most likely to be affected by rising temperatures, challenging the concept the country's weather extremes would make them less susceptible to global warming, a new study has found.
The research, published in the Global Change Biology journal, studied the upper-canopy leaves of 218 plant species across 19 sites around the world.

Trees start to lose leaf function and can die if exposed to prolonged excessive heat. Photo: Nick Moir

Ten of the sites were in Australia, reflecting the nation's remarkable array of biomes, said Owen Atkin of the ARC Centre of Excellence in Plant Energy Biology at the Australian National University, who led the study.
The potential for damage from warming temperatures was found to be most severe in hot inland areas in mid-latitude regions. In Australia, these areas include study sites near Kalgoorlie in WA, Alice Springs in the Red Centre and Renmark in SA.

Studies have tended to focus more on the impacts of rising temperatures on fauna rather than plants.  Photo: Nick Moir

"We've been getting some amazing extremes," Professor Atkin said. Leaf temperatures can be 5-10 degrees above the air temperatures, putting them in the mid-50s in some places in January.
Upper canopy leaves tend to die when thresholds are breached, reducing the ability of the plants to grow.
"If those events happen often enough, then the tree may well die," he said. "Their tolerance is not high enough to cope with these new extremes."
The findings are important because previous studies of warming have tended to focus on how animals will respond. Since the inland regions where the heatwave extremes are becoming the worst are on the edges of important wheat and other agriculture zones, the results also underscore the need to develop more heat-tolerant varieties, Professor Atkin said.

Heatwaves in Australia: Dr Sarah Perkins-Kirkpatrick explains the ins and outs of this sweltering weather phenomenon. Produced in association with UNSWTV.

Andy Leigh, an ecologist at the University of Technology Sydney, such the study was important because it spanned a range of global conditions.
While Australia was known to have plants able to cope with a variable climate "there's a limit to how far we can push acclimation", she said.
Some plants would be able to adjust better than others to higher temperatures but the result of surviving would be less reproduction or other activity.
"Anything that costs plants effort is gong to come at the cost of productivity," Associate Professor Leigh said.
A separate report out on Tuesday by Nature Climate Change found that a 1 degree increase in global temperature would reduce global wheat yields by between 4.1 and 6.4 per cent.

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