ABC News Online, Posted Tue Aug 5, 2008 9:00am AEST
Updated Tue Aug 5, 2008 11:19am AEST
- Audio: Big trees demonstrate carbon potential (AM)
Scientists and environmentalists have long promoted the value of trees in fighting pollution, but they are re-thinking just how valuable Australia's forests are in helping the fight against greenhouse gases.
For the first time, a research team has been able to measure exactly how much carbon Australia's untouched forests can absorb.
The scientists found that the forests can store three times more carbon than previously thought.
The research took 10 years and endless field trips by Australian National University scientists visiting 240 sites scattered across Australia's vast remaining natural forests.
The result is, for the first time, an accurate measure of the role trees can play in the climate change solution.
Brendan Mackey is a professor of environmental science and is part of the research team.
"We looked at half of Australia's remaining forests and our estimate is they can store around 33 billion tonnes of CO2. These are very big numbers," he said.
The result is especially startling compared with what scientists had previously thought. At last count they estimated temperate forests could store around 200 tonnes of carbon per hectare.
"If all those forests were cleared and all of the carbon in the biomass in the soil released into the atmosphere, that would be the equivalent of about 80 per cent of Australia's annual emissions every year for 100 years. So we really have to protect our natural forests," Professor Mackey said.
The largest stocks of carbon were found in the mountain ash forests of the central highlands of Victoria and Tasmania.
The eucalypt trees in these undisturbed areas are up to 80 metres tall, with trunks around 4.5 metres in diameter.
Some of the trees are 300 to 400 years old and tower above a dense layer of rainforest.
"It's the big old trees that have a very high amount of carbon and also the coarse woody debris - the dead standing trees and the dead logs on the ground that are there in the natural undisturbed forests," researcher Heather Keith said.
About half of Australia's forests have been cleared in the last two centuries. In three quarters of these, carbon stocks have been degraded by human activities such as logging.
These scientists say it is crucial that what is left remains intact if trees and forests are to help soak up the excess carbon dioxide in the atmosphere and do their bit to fight global warming.
The Wilderness Society's Virginia Young agrees.
"It's the forests that enable us to act early and make deep cuts, and that applies whether its Australia or globally," she said.
- Adapted from a story first aired on AM, August 5.