Saving the Amazon

Abstract

Two hours by jeep from the city of Manaus, deep in the Amazon jungle, Rob Bierregaard has carefully marked off ten hectares of a tract that is earmarked for development and is trapping, cataloging and tagging the exotic, brightly colored native birds. When this site and numerous other swatches of up to ten thousand hectares have been cataloged, the surrounding forest will be cut, leaving Bierregaard's sites as eerie jungle relief in the midst of cattle range or cropland. Bierregaard is one of 15 or 20 American and Brazilian scientists working on a project to determine the minimum area capable of preserving a maximum number of plant and animal species. The project, conducted by the World Wildlife Fund and Brazil's National Institute for Research on Amazonia, will compare the success of the various-sized areas in preserving the incredibly diverse insect, animal and plant life of the largest rain forest in the world. Its aim is to provide scientific advice to the Brazilian government on how best to enforce a recent government dictum requiring that 50 percent of the land bought for development in the 4.9-millionsquare-kilometer Amazon region be left in its natural state. Parcel size and shape will be important in determining the future of such highly mobile, symbiotic jungle species as the birds that exist by flying before advancing lines of army ants and snatching their fleeing prey. When left alone, tropical moist forests like the Amazon excel at supporting genetic diversity. According to one National Research Council report released this year (Research Priorities in Tropical Biology), (t)here are probably at least 4.5 million kinds of organisms in the world, of which at least three million occur in the tropics. For example, Southeast Asia, a region smaller than Western Europe, contains 25,000 species of flowering plants or about one in 10 of the world's flora, ecologist Norman Myers says. Great Britain, on the other hand, has 1,430 native plant species, while the Malay Peninsulaabout only half Great Britain's sizehas 7,900. One in five birds and an estimated 20 percent of all known higher plant species evolved in the Amazon's lowland forests. In his book The SinkingArk, Myers notes that while one hectare of temperate-zone forest usually carries no more than 10 different species of trees, a single hectare near Manaus features 235 separate tree species. But the wealth of ecological diversity common in tropical forests also signals how rare many of their species are. Up to one half of the 100 tree species typical of any hectare in the Amazon forest may not be found in another hectare as little as one kilometer away, Myers says. Despite their remote origins, many tropical-forest species still benefit human welfare. They supplied the original stock for many food staples, including rice, millet, cassava, yams, bananas, pineapple and sugarcane. Countless more await exploitation. In New Guinea alone some 250 different trees bear edible fruit, though only 43 have been cultivated. Fruit of the Chinese gooseberry is 15 to 18 times richer in vitamin C than is orange juice. And Myers cites the hitherto uncultivated mangosteen of Southeast Asia as a hidden pearl; it has been called perhaps the world's best tasting fruit. Crossbreeding wild relatives with refined crops can offer farmers fresh gene plasm to resist new pests, diseases and other blights that threaten their fields. Or they can be used to increase the yield and nutrition of their harvest. To grasp the impact tropical species can offer, one $35,000 importation of three types of parasitic wasps allowed Florida citrus growers to save $25 million to $35 million in pesticide costs. A virtual pharmacopoeia, tropical moist forests are also home to most of the world's drug-yielding plants. Roughly 70 44 V