Carbon surprise: By taking detailed measurements, ANU scientists have estimated that Australia's unlogged eucalypt forests hold an average of 640 tonnes of carbon per hectare.
Credit: Sarah Rees
BRISBANE: Australia's native forests may be storing three times more carbon than previously thought, a new report says.
Green Carbon, published this week by the Australian National University in Canberra, argues that the method used by the Intergovernmental Panel on Climate Change (IPCC) to calculate the carbon storage value of forests may significantly underestimate the true figures.
Until now, the IPCC has recommended that if local data is unavailable, temperate forests should be valued as storing 217 tonnes of carbon per hectare. This is an average of values from forests in several parts of the world.
"Importance of good data"
However, by taking detailed measurements from real forests, scientists at ANU now estimate that Australia's unlogged, natural eucalypt forests hold an average of 640 tonnes of carbon per hectare.
"Protecting the carbon in Australia's and the world's natural forests is no longer an option – it is a necessity," said Brendan Mackey, an environmental scientist and the report's lead author.
Mackey's team measured the height and diameter of trees and the amount of dead plant material in forests, and used satellite data to accurately map forest boundaries. Satellite data was also used to estimate the rate of photosynthesis, to estimate how much carbon dioxide was being absorbed.
The study shows the importance of good local data for accurately valuing carbon storage, even if gathering this data is "not straightforward" and requires a combination of fieldwork, remote sensing and computer modelling, said Mackey.
The report estimates that, if left unperturbed, the newly discovered carbon stored in Australia's forests is equivalent to "avoided emissions" of 460 million tonnes of carbon dioxide per year for the next 100 years.
Old growth forests
The research also found that formerly logged forests and plantations stored carbon much less efficiently than old growth forests, and suggested that there was an urgent need to protect natural forests to help control climate change.
"The carbon stored in natural forests is a larger and more reliable stock than the carbon stored in commercially logged forests and plantations," Mackey explained. "People have been focussing on emissions from burning fossils fuels – [they] are now realising that it's important to protect the forests."
In undisturbed, old growth forest, the majority of carbon is stored in very old and large trees, which are not present in logged forests and plantations, he said.
However, environmental scientist Rod Keenan, from the University of Melbourne in Victoria, said that calling for an immediate end to logging in native forests is not the answer.
"Much of what is called for [in the study], in terms of reduced pressure on native forest, is already happening," Keenan said. He added that some logging of native forests should continue, because plantations are more expensive and take time to mature, while imported wood often comes from poorly-managed forests.
