Australia's old-growth forests can store up to five times more carbon than previously thought, scientists say, as they warn that natural forests are crucial in the worldwide fight against climate change.
A study on the role of natural forests in carbon storage has found that unlogged natural eucalypt forests in Australia's south-east store about 640 tonnes of carbon a hectare, while intact old-growth forests in Victoria and Tasmania store up to 1200 tonnes a hectare.
The study was carried out by the Fenner School of Environment and Society at the Australian National University.
The report's co-author, Professor Brendan Mackey, said the leading world climate change body, the Intergovernmental Panel on Climate Change, had got carbon storage levels wrong.
The scientific body said the average carbon stock in temperate forests was 217 tonnes a hectare.
The report by Professor Brendan Mackey, Heather Keith, Sandra Berry and David Lindenmayer found that natural forests stored almost three times as much carbon as plantations did.
Professor Mackey said, ''Protecting the carbon in Australia's and the world's natural forests is no longer an option: it is a necessity.''
He said the value of forests, especially natural ones, would have to be considered in terms of their carbon storage power.
Forests should not be included in the emissions trading scheme but the international definition of a forest would have to be reworked, to differentiate between the higher value that should be accorded to natural forests rather than to plantations.
Half Australia's forests have disappeared in the past 220 years and the carbon stocks in more than half of the remaining forests have been degraded by activities such as logging.
Professor Mackey warned that if the clearing of natural forests continued, ''then the C02 released will significantly increase concentrations of greenhouse gases in the atmosphere''.