SUSTAINABLE forestry can do more harm than good, tropical forestry experts warned the AAAS. New Scientist Feb 22 1997
There are times when conservationists should forget about forcing timber companies to restore forests after logging, and try instead to purchase lightly logged land cheaply to set aside as preserves. in some forests, loggers harvest only mahogany, which fetches the highest price of any tropical hardwood. But mahogany is so rare-often only one tree per 5 or 10 hectares-that such logging can leave the forest ecosystem relatively undamaged. in the Chimanes forest of lowland Bolivia, for example, logging for mahogany destroys only 4-5 per cent of forest cover. "It looks almost like untouched forest," says Richard Rice, a resource economist with Conserva- tion International in Washington DC. But things take a dramatic turn for the worse when logging companies try to follow the "sustainable forestry" management plans supported by many environmentalists. A cornerstone of these plans is that loggers must provide for the regeneration of the tree species that they remove. This can have a devastating impact, says Rice and his colleague Ted Gullison ' an ecologist at imperial College, London. Gullison has shown that mahogany seedlings need large clearings if they are to survive. So to allow for the regeneration of mahogany, logging companies must clear much greater swaths of forest than the logging alone requires. A second pillar of green forestry-harvesting a wider variety of species-also destroys much more forest than selective mahogany logging. Both practices also reduce the profits of the logging companies, says Rice. Using computer models, he projected the effect of standard and sustainable management practices over 50 years in the Chimanes forest. This showed that conventional logging would lead to 2.5 times as much profit and 60 per cent less damage compared with "sustainable" logging. Gullison and Rice suggest that conservationists should take advantage of the fact that by removing mahogany, timber companies vastly reduce the economic value of logged lands. "That to me screams opportunity," says Rice. He says that con- servation organisations could buy almost virgin forests at bargain basement prices. Near Chimanes, for example, the Bolivian government has doubled the size of one national park by purchasing logged land. This approach to conservation may not work everywhere. In tropical Asia, for example, loggers cut more trees per hectare because they are more valuable. The land also has higher agricultural value because the soils are richer than those of Amazonia, says David Cassells, a resource economist with the World Bank in Washington DC. Even in South America, Rice's plan would result in the loss of some ecological niches created by the towering mahogany trees. Many conservationists find it difficult to accept sacrificing mahogany to save the rest of the forest. But this, says Rice, is the lesser of two evils: "Let's not sacrifice the forest to save mahogany."