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...take for us to get serious about saving our environment? When will environmentalism move from being a philosophy promoted by a passionate minority to a way of life that governs mainstream behavior and policy? How can we understand that Earth is one big natural system and that torching tropical rain forests and destroying coral reefs will eventually threaten the well-being of towns and cities everywhere...
Ecosystems are naturally resilient, but human impact can reduce their ability to bounce back in many ways. Rain forests withstand some degree of cutting, for instance, but once forest fragments shrink beyond some unknown threshold, the entire system loses its ability to recover. page refers to a recent study led by the University of Michigan's Lisa Curran, who contends that human activities such as logging may have doomed Indonesia's great dipterocarp trees, the anchor of its rain forests...
...dipterocarp fruit, with the result that no new dipterocarp trees are taking root in the areas studied by Curran and her colleagues. Since a host of creatures ranging from the orangutan to the boar are dependent on the dipterocarps, the trees' disappearance may ultimately doom Indonesia's rain-forest ecosystem. PAGE scientist Nigel Sizer of the World Resources Institute notes that similar problems associated with fragmentation loom over all but the largest remaining forests on Earth...
Biologists estimate that more than half the species occur in the tropical rain forests. From these natural greenhouses, many world records of biodiversity have been reported--425 kinds of trees in 2.5 acres (1 hectare) of Brazil's Atlantic forest and 1,300 butterfly species from a corner of Peru's Manu National Park, both more than 10 times the number from comparable sites in Europe and North America. At the other extreme, the McMurdo Dry Valleys of Antarctica, with the poorest and coldest soils in the world, still harbor sparse communities of bacteria, fungi and microscopic invertebrate animals...
Earth's biodiversity (short for biological diversity) is organized into three levels. At the top are the ecosystems, such as rain forests, coral reefs and lakes. Next down are the species that compose the ecosystems: swallowtail butterflies, moray eels, people. At the bottom are the variety of genes making up the heredity of each species. How much biodiversity is there? Biologists have described a total of between 1.5 million and 1.8 million species. Yet this impressive achievement is only a small beginning. Estimates of the true number of living species range, according to the method employed, from 3.6 million...