Old-growth forests won't save planet

Martin Moroni and Ian Ferguson
WA Today, September 4, 2011

Managing regrowth may help us turn green, write Martin Moroni and Ian Ferguson.

IN AUSTRALIA, too often we're told the solution to all environmental problems is locking all native forests in unmanaged reserves, where they'll be immortal, grow forever and continuously suck large amounts of greenhouse gases from the atmosphere.

We're led to believe all forested landscapes can become old growth, and that forest management destroys forests. This is simplistic, flawed and represents missed opportunities for the environment, society and the economy.

Most of Australia's forests aren't full of enormous old trees and most of our old-growth is already in reserves. Just 6 per cent of Australia's forests are managed for wood production.

Managed forests maintain biodiversity, water quantity and quality and produce a variety of other goods and services, including carbon sequestration, employment, income and other opportunities to society.
Sure, photosynthesis takes carbon from carbon dioxide, an atmospheric gas, to form wood. Dry wood is half carbon by weight and each tonne of carbon absorbed from the atmosphere into wood came from about four tonnes of carbon dioxide.

So wood products store carbon in them and trees can absorb some carbon dioxide from the burning of fossil fuels. But trees can't absorb all the carbon released from the burning of fossil fuels. To do so would require us to produce enough wood to form a 30-cubic-kilometre block of wood almost four times the height of Mount Everest, from forests each year. This is impossible. We must focus on reducing the burning of fossil fuels.

Growing forests absorb carbon dioxide from the atmosphere, but as they die they emit it. Wildfires frequently burn our forests releasing huge amounts of carbon dioxide back to the atmosphere and preventing many forests from becoming old-growth.

Since 2003, 3.5 million hectares have burnt in Victoria. Many of our prime forests require high-intensity wildfires to regenerate - they cannot remain as old-growth indefinitely. Valuable as it may be, storing carbon in forests doesn't change our use of fossil fuels.

Cutting trees down is the only way forests can reduce our use of fossil fuels. This is done by using wood instead of fossil fuels for heat or electricity and, most effectively, using wood instead of products associated with large emissions.

For example, the use of metal, concrete and plastic in construction produces more greenhouse gasses than when wood is used in their place.

Ideally, we should substitute fossil fuels and emission-intensive materials with renewable alternatives like wood.

Globally, wood products store an additional 150 million tonnes of carbon annually and landfill another 44 million tonnes, equivalent to removing 700 million tonnes of carbon dioxide from the atmosphere.

Wood use in residential house construction instead of non-wood alternatives prevented 483 million tonnes of carbon dioxide from being emitted in 2007. By 2030 the global use of forest bio-energy will prevent 1000 million tonnes of fossil fuel carbon emissions annually.

These initiatives lack support in Australia where we are missing easy, proven opportunities to reduce greenhouse gas emissions with forests, unlike their rapid uptake in Europe and North America.

Wood products are traded on the global market. Australia has an annual $2 billion deficit in wood products, annually importing 600,000 to 900,000 cubic metres of sawn wood extracted from thousands of hectares of international forests each year, much of which are managed to lesser standards than Australia's forests.

Withdrawal of more Australian native forests from management can be expected to increase greenhouse gas emissions from more intensive harvesting elsewhere, and from increased transportation of imports. That is not a green outcome. Sustainable management of Australia's native regrowth forests is.

Dr Martin Moroni is senior research scientist, forest carbon, at Forestry Tasmania, and Ian Ferguson is professor emeritus of forest science, University of Melbourne.

FOOTNOTES:

• The authors of the above article clearly have a vested interest in the continued logging of Australia native forests.
• Bushfires do not prevent native forests "becoming old growth", nor do they destroy forests to the same extent that clear fell logging and burning them does.
• The authors neglect to mention that about 80% of the logs extracted from native forests ends up was woodchips, the vast majority of which are exported to Japan.
• Old growth forests don't "emit carbon", they continue to store it
• The authors neglect to mention that logging native forests, particularly old growth ones, put very significant net carbon emissions into the atmosphere, that are are not offset by regrowth forests within a 200 year period