The tree-covered regions of our planet have always been a valuable natural resource, both for the timber they produce and, ironically, for the land on which they stand, since that can be turned to other uses. As a result, many of the forests that once clothed our planet have been cleared, with the land now used for agriculture, cities or towns, and the timber for construction, to make paper or simply burnt to provide energy. Ecological footprint calculations show that Australia exploited roughly 0.5 global hectare of forest per person in 2003, making up 8 per cent of our total footprint. Australian forests are harvested for timber and woodchips, with a large proportion of woodchips coming from native forests for export to countries like Japan. Most nations use less (the global average is only 0.17 global hectares), but a few (the USA, Canada, Sweden and Finland) need more because their forest industries are bigger. Like Australia, many nations harvest their forests for export to other countries. In terms of forest biocapacity we do quite well, with more than three global hectares available per person (again well above the global average of less than one). Much of that is held in national parks and other reserves and so is not available for exploitation, though the forests provide other vital ecological services, protecting biodiversity, soil and water quality, storing carbon and providing somewhere to get away from it all. The area of plantation forests is increasing in Australia, although they can actually reduce biodiversity depending on whether they are planted on former native forest land or farming land. Since European settlement, a quarter of our native forests and woodlands have gone, replaced by farms and settlements. We hear most about the loss of rainforests, a third of which have vanished, though they make up only 3 per cent of Australia's forest resources. Agriculture is the major driver of land clearance, and that has a big impact on the vital task of controlling carbon dioxide levels in the air. Land clearing releases carbon dioxide into the atmosphere, as the fallen trees are burnt or allowed to rot, and the crops that replace them are usually not as good at storing carbon. Fortunately, there is some good news. There is less land clearing now, and carbon dioxide emissions from forest related activities dropped by 74 per cent between 1990 and 2005. The biggest improvement has been in Queensland, the major contributor (mostly due to land clearing) in Australia. Stronger government policy has helped to maintain native forests while still supporting the forest industry. The push is to make forestry more sustainable, conserving the resources with their many benefits, while still making use of them. This is backed by a major scientific research effort, including measurement and planning for forest biodiversity, managing forests in drier areas and planting trees better suited to particular environments. New practices have been developed, such as watering trees with effluent and using computer models to help make forestry decisions. As a result our forests are becoming more productive and are expanding into drier areas, with extra benefits such as the control of salinity, and, better still, the revegetation of previously cleared land. Related sites
Other boxes Box 2. Tell me about carbon offsets Box 3. What difference can we make?
|
     |
||||||
External sites are not endorsed by the Australian Academy of Science.
Posted December 2008.
The Australian Foundation for Science is a supporter of Nova.
This topic is sponsored by Australian Government Department of Climate Change.
© Australian Academy of Science