Planet Of The Year: Biodiversity The Death of Birth

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Biologists have identified numerous "hot spots" where ecosystems are under attack and large numbers of unique species face an immediate threat of elimination. Among the troubled areas: Madagascar, where more than 90% of the original vegetation has disappeared; the monsoon forests of the Himalayan foothills that are being denuded by villagers in search of firewood, building materials and arable land; New Caledonia, 83% of whose plants occur nowhere else; the eastern slope of the Andes, as well as forests in East Africa, peninsular Malaysia, northeast Australia and along the Atlantic coast of Brazil.

Since less than 5% of the world's tropical forests receive any protection, the stage is set for mass extinctions. Many plants and animals are doomed, no matter what measures are taken. Some researchers estimate that at least 12% of the bird species in the Amazon basin, as well as 15% of the plants in Central and South America, can be counted among what Janzen calls the "living dead." Many tropical mammals and reptiles face only bleak survival under what amounts to house arrest in game parks and zoos.

Why are so many species and environments threatened? The main reason is that throughout the tropics, developing nations are struggling to feed their peoples and raise cash to make payments on international debts. Many countries are chopping down their forests for the sake of timber exports. In Central America forests are giving way to cattle ranches, which supply beef to American fast-food chains. The pressures on forests have led Janzen, who has spent 26 years struggling to save Costa Rica's woodlands, to conclude that "everything outside parks will be gone, and everything inside the parks is threatened."

Efforts to stop the destruction run into moral as well as practical obstacles. How can developed nations demand onerous debt payments and ask the debtors to preserve their forests? How can countries worry about biodiversity when their people are concerned with feeding themselves?

To begin with, the rich nations must reduce the debt burden of the poor. But just as important is a concerted campaign to convince the people of developing countries that it is in their own long-term interest to preserve their environments. Wiping out forests may make developing nations momentarily richer, but it is bound to produce a poorer future.

Experience has shown the Third World that destruction of forests can have disastrous consequences. Forests are vital watersheds that absorb excess moisture and anchor topsoil. Deforestation contributed to the recent droughts in Africa and the devastating mud slides in Rio de Janeiro last year. In Costa Rica topsoil eroded from bald hills has greatly shortened the life of an expensive hydroelectric dam. Alvaro Umana, Costa Rica's Minister of Industry, Energy and Mines, estimated that the surrounding watershed might have been protected 20 years ago for a cost of $5 million. Now the government must reforest the watershed at ten times that price.