Australian Forests Best at Locking Up Carbon

June 16, 2009 -- Mountain ash forests in Australia are the best in the world at locking up carbon, a new study has found.

And one of the authors said climate change negotiations should give more attention to protecting forests like these.

Environmental scientist, Brendan Mackey of the Australian National University and colleagues report their findings in today's issue of the Proceedings of the National Academy of Science.

"Currently everyone is focussed on how to reduce emissions from deforestation and degradation in developing countries," said Mackey.

"But what this points to is that we can't forget about emissions from natural forests in economically developed countries like Australia."

In the first study of its kind, Mackey and colleagues compared the amount of carbon per unit area locked up in 132 forests around the world. Forests ranged from the Amazon in the tropics to temperate moist forests, such as stands of mountain ash (Eucalyptus regnans) in Victoria's Central Highlands.

They calculated the total biomass locked up in living and dead plant material and the soil of each forest.

Mackey and colleagues found the highest amount of carbon was contained in a forest located in Victoria's Central Highlands, which held 1900 tons of carbon per hectare.

Related Content:

• Planet Earth Live: Forests
• Wildfires Could Curb Climate Change
• HowStuffWorks.com: Deforestation
• More Discovery News

This most "carbon-dense" forest was a stand of unlogged mountain ash over 100 years old. Mountain ash live for at least 350 years, said Mackey.

He said similar but lower carbon densities were found for other temperature moist forests in New Zealand, Chile and the Pacific coast of North America.

By comparison, the average tropical forest had somewhere between 200 and 500 tons of carbon per hectare, said Mackey.

"The common understanding is that tropical forests store the most carbon because they're the most biologically productive and have the most plant growth," said Mackey.

But, he said, researchers have missed the fact that nearly half of the carbon locked up in temperate forests like the mountain ash, is in fallen trees and other dead plant material.

In tropical forests, dead plant material is rapidly decomposed and carbon dioxide is released into the atmosphere through respiration.

By contrast, moist temperate forests are warm enough to encourage good growth rates, dead plant material decays much more slowly and carbon-rich dead biomass lasts much longer.

Mackey said the findings reinforce the role of forests in storing carbon and in mitigating climate change.

He said the research especially underscores the importance of protecting carbon-dense forests in developed countries.

Under the Kyoto Protocol, countries are not required to account for carbon lost through degradation and deforestation of their native forests, said Mackey.

He said, the upcoming Copenhagen climate change negotiations should rectify this.

The forest industry argues logging old growth forests is important to reduce the risk of bushfire, which releases CO2 emissions.

"If we lock up and leave these forests, what we're actually doing is increasing the risk that these forests will burn down," Allan Hansard, CEO of the National Association of Forest Industries, told ABC Radio today.