Forestry consultant, and member of the Institute of Foresters of Australia.
The Age, October 18, 2006
THE start of Victoria's renewable energy trading scheme in January signifies a welcome Government willingness to step up the fight against global warming.
Yet environmental groups continue to pressure the Government to act against native forest logging and close Victoria's hardwood timber industry - a debate that was reignited recently by an ABC Four Corners program.
Although not obvious to most Victorians, there is a counter-productive link here that needs to be acknowledged if we are to make headway against global warming.
Sustainable logging is now restricted to just 10 per cent of Victoria's native forests. Yet anti-logging campaigns continue to attribute it with damaging environmental impacts out of proportion to its nature and extent. This includes the erroneous claim that timber
production promotes global warming by diminishing the capacity of native forests as carbon sinks when the opposite is true.
It is widely appreciated that growing forests sequester atmospheric carbon that effectively counteracts greenhouse gas emissions. But rates diminish as growth slows with age. Over time, undisturbed forests store carbon but sequester little new carbon once they reach maturity and
become "old growth".
But sustainable harvesting maintains a continuous cycle of vigorous growth that actively sequesters carbon at high rates while annually transferring carbon storage from trees to various wood-based products.
Losses of carbon occur along the way, most notably through greenhouse gas emissions from mechanised timber harvesting, log cartage, primary processing, and from slash burning to promote forest regeneration. But the losses are relatively small compared with the rate of enhanced carbon sequestration and storage by logging regrowth.
Sustainable logging in Victoria's designated wood production zones produces about 1.5 million cubic metres of hardwood sawlogs and residual logs a year from an estimated total harvested biomass of about 2.1 million cubic metres, including roots, bark, branches and foliage. The
concept of sustainability dictates that annually harvested amount is replaced by an equivalent volume of growth.
Carbon sequestered each year in new biomass growth in Victoria's production zones is estimated to be equivalent to saving 2.6 million tonnes of carbon dioxide emissions. This is net of emissions from fuel and power use inherent to timber production and emissions from the regeneration process. It is also additional to the carbon that could have been sequestered if the forest had alternatively been left unlogged.
Putting this into perspective is that clean energy produced from Victorian wind farms has been estimated to save 250,000 tonnes of greenhouse gas emissions a year. Put another way, if anti-logging campaigns were to close Victoria's native forest timber industry, 10 times as many wind turbines as now exist would be required just to make up for the carbon sequestration lost by "locking up" wood production forests.
Enhanced carbon sequestration is only part of the "greenhouse" benefit of sustainable logging. Australian domestic hardwood production also offsets imports of tropical hardwoods and the use of steel, aluminium and concrete that offer poor environmental outcomes.
Tropical timber imports - often illegally produced from unsustainable sources - have increased by 50 per cent since 2001 as state governments have reduced the native forest harvest. This has been accompanied by additional greenhouse gas emissions inherent to international freight.
Unfortunately, this is likely to continue as we have few hardwood plantations being grown for solid wood production.
The use of substitute products is also believed to have increased as governments have reacted to anti-logging campaigns. These are problematic because they rely on finite resources and because their manufacture involves substantially greater carbon emissions compared with producing a similar unit of renewable solid timber. In particular, greenhouse gas emissions from steel and aluminium making are several hundred times greater than that associated with timber.
No one disputes the benefits of focusing on conserving biodiversity as is now the case in most of our native forests. But it must be recognised there are also substantial environmental benefits associated with sustainably harvesting wood from a portion of our forests.
At a time when environmental awareness is starting to drive urgent political action to tackle global warming, unwarranted campaigns to "save" a minor portion of our forests from sustainable timber production threaten to counteract much of the good work being done by governments and Australians to embrace cleaner "green" energy alternatives.