Julia Hinde reports from the annual American Association for the Advancement of Science meeting in Seattle
SUSTAINABLE management of tropical forests may cause more environmental damage than unrestricted logging, scientists warn.
Conservationists have long argued that sustainable forestry, where the harvesting of trees is managed to maintain species yields, provides a suitable compromise between strict conservation and uncontrolled exploitation of timber.
But at this week's meeting of the American Association for the Advancement of Science in Seattle, a group of scientists challenged this view, suggesting that sustainable management may not just be less profitable than the cut-and-run approach, but also up to twice as harmful for the environment.
Ted Gullison, previously of Princeton University and now at Imperial College, London, has spent a decade studying mahogany, tropical America's most valuable timber resource, with colleagues Richard Rice and John Reid, of Washington-based Conservation International.
Dr Gullison said that for local mahogany logging companies, which make vast profits, South America's unstable political and economic climate, combined with the unpredictability of nature and current high interest rates, mean they have little economic incentive for sustainable management of a species which might take 100 years to reach maturity.
He added that current practices often do little damage because of the low density of the species. Because mahogany is incapable of growing under the shady canopy of the tropical forest so areas of forest would have to be cleared, and repeatedly thinned, for it to be sustainably managed.
Sustainable logging, which involves more intensive harvesting of a variety of species, could have a much greater effect on the biodiversity, Dr Gullison said. "Efforts to promote sustainable forestry, in the absence of regulations, can make the problem worse," he added. "Many of the things that foresters do, like thinning, consist of removing about three-quarters of the trees in an area. It looks like there is a high degree of specialisation between insects and trees. If you remove three-quarters of the tree biodiversity, you are guaranteed to be wiping out a proportion of the insect biodiversity too. If the maintainance of biodiversity is of paramount importance, a low-impact, albeit unsustainable, approach may become the preferred choice."
Nigel Sizer of the World Resources Institute, Washington said: "Some very respected researchers are coming out with data which question some of the fundamental assumptions of tropical forestry."
Less than 1 per cent of tropical rainforest is sustainably managed.