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Death of old-growth forests could mean greater changing climate

Media release


Researchers at Curtin University have found that the effects of climate change and logging on old-growth forests could actually increase the level of carbon dioxide in the atmosphere.

Director of Curtin’s Biodiversity and Climate Institute, Associate Professor Grant Wardell-Johnson, said this could make the effects of climate change more severe than predicted.

“Particular forests do well in different environments and as the climate changes and rainfall patterns are altered, we will see the forest-types of southern Australia change,” Associate Professor Wardell-Johnson said.

“On average, these new forests will have a lower biomass than those they replace and will store less carbon, leading to a reduction in the amount of carbon the terrestrial environment can store, and more carbon in the atmosphere.”

Associate Professor Wardell-Johnson said the logging of old-growth forests also presented a problem.

“Due to the size of the trees and the large below-ground carbon pools, old-growth forests store much more carbon than any other type of forest,” he said.

“Replacements, such as newer or plantation forests do not store the same level of carbon, even including what is stored in wood products. New trees take over a century to reach the same size as those of old-growth forests – if they ever do. Trees can remain in a mature or senescent state for centuries.

“New forests also use much more water than old-growth forests, in their rapid growth stage. This is going to be problematic based on continuing drying trends for much of southern Australia – particularly the south-west.”

Despite this, Associate Professor Wardell-Johnson said authorities in Tasmania were still allowing the logging of old-growth forest each year.

“Based on 2009 announcements, Forestry Tasmania plan to take about 30 per cent of the Tasmanian sawlog quota from public land harvested over the next 20 years from old-growth forests,” he said.

Old-growth trees are also being felled for urban expansion, infrastructure and agriculture in all States and Territories, and for mining in several States. In addition, firewood collection is a major attrition on old-growth in all States.

“This is too much if we are to take carbon seriously,” Associate Professor Wardell-Johnson said.
Associate Professor Wardell-Johnson said the carbon in old-growth forests must be given an economic value if it is to be protected.
“Currently the carbon in the old-growth forests of Australia is not considered an economic asset and it is not recognised in legally binding inter-governmental schemes,” he said.

“We need to provide the carbon stored in these trees with a value and we need to make sure that they are protected as much as is possible.”

Notes to Editor:

Associate Professor Grant Wardell-Johnson is the Director of the new Curtin Institute for Biodiversity and Climate (CIBC), which was officially established this year, and is designed to harness Curtin’s substantial expertise in this area and maximise the potential of national and international collaborations to better investigate the impact of human activity on the region’s biodiversity and climate.

The primary focus themes of the Institute are evolution, conservation, resilience and integration, all of which are critical to understanding the complexity of the biosphere and how it is affected by human activity.


Associate Professor Grant Wardell-Johnson; Director, Curtin Institute of Biodiversity and Climate, Curtin University
Tel: 08 9266 3702, Mobile: 0413 628 201; Email: