One Earth, One Future Our Changing Global Environment (1990) / Chapter Skim
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10. Vanishing Forests and Vanishing Species
10. Vanishing Forests and Vanishing Species
Pages 116-130
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From page 116... ...
Recently, scientists and the public have focused their concern on deforestation in the tropics, particularly because tropical forests contain more than half of the world's plant and animal species and because tropical soils are notoriously unproductive once cleared of their forest cover. They are also concerned because as trees are cut and burned, or as they decompose, they release carbon back to the atmosphere, adding to the carbon released as humans burn fossil fuel to satisfy their energy needs.
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From page 117... ...
Within 50 years, tropical rain forests wouIcl vanish from 13 additional countries. Philip Fearnside, of the Brazilian National Institute for Amazonian Research, analyzed satellite photographs to decipher de
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From page 118... ...
Eneas Salati, a hydrologist and climatologist at the University of Sao Paulo in Brazil, and his colleagues calculate that if current trends continue, forests will be completely cleared from most of the Amazonian states by the year 2000.
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From page 119... ...
Robert Repetto, an economist at the World Resources Institute, concluded in a 1988 report that tax and tracle regimes, land tenure laws, agricultural resettlement programs, and administration of timber concessions with loggers are but a few of the policies that aggravate deforestation. He finds that these policies can contribute significantly to the wasting of forest resources.
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From page 120... ...
Salati explains that, although there are very few studies of soil erosion and river sediment loads in tropical areas, the few existing data do show that erosion losses can be 100 times greater in soils changed to agricultural use when compared to similar soil covered with forest. On a regional scale, forest ecosystems recycle the rainwater back to the atmosphere through evaporation from the soil and leaf surfaces and through transpiration from plants, a process so efficient that ecologists refer to tropical forests as "rain machines." The rainfall patterns in the Amazon basin, and probably other regions such as the Brazilian central plateau, depend on the existence of the forests.
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From page 121... ...
Salati, with colleagues Reynaldo Luiz Victoria, also of the University of Sao Paulo, Luiz Antonio Martinelli, of the Centro de Energia Nuclear na Agricultura of Brazil, and Jeffrey Richey, of the University of Washington, find, based on a large range of estimates about rates of deforestation and how much biomass the forests contain, that annual emissions of carbon dioxide from deforestation in the Amazon alone account for 4 to 25 percent of carbon dioxide emissions to the atmosphere worldwide. Other estimates indicate that deforestation could
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From page 122... ...
Roger A Sedjo, a senior fellow at Resources for the Future, and colleagues cal culate that new forest plantations covering an area of approximately 465 million hectares would be required to remove 2.9
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From page 123... ...
it is unlikely that trees will be planted on this scale, but reforestation projects could make modest dents in the accumulation of carbon dioxide and, at the same time, provide other benefits for water quality and for species that live in the forests. VANISHING SPECIES it is nearly impossible for a biologist to be present at the precise moment when the last individual of a species languishes in a tropical forest.
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From page 124... ...
Several areas stand out, according to Norman Myers, an environmental consultant with extensive experience in the tropics, including the Choco forest of Colombia, the Napo center of diversity in Peruvian Amazonia and other centers around the fringe of the Amazon basin, the Tai Forest of Cole d'Ivoire, the montane forests of East Africa, the relict wet forest of Sri Lanka, the monsoon forests of the Himalayan foothills, northwestern Borneo,
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From page 125... ...
Few people realize, as Mark Plotkin, of Conservation International, points out, that a typical American breakfast of cornflakes, bananas, sugar, coffee, orange juice, hot chocolate, and hash brown potatoes is based entirely on plant species that originated in the tropics. Many currently underexploited tropical species could become familiar sights in U.S.
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From page 126... ...
. Horizontal shading is the present range and vertical shading the potential range, with effective carbon dioxide doubling.
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From page 127... ...
As a consequence, much of the potential range will remain unoccupied. (Reprinted from Toward an Understanding of Global Change.
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From page 128... ...
Because many of the world's important crop species originated in the tropics, their relatives that provide the means to maintain and improve our crops can only be found there. A wild relative of the domestic tomatodiscovered in 1962 quite by accident while Hugh Iltis, director of the University of Wisconsin Herbarium, was waiting to pass a landslide on an excursion in the Peruvian Andes after almost two decades of research increased the sugar content of the tomato and raised its commercial value by millions of dollars.
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From page 129... ...
, species of forest trees migrated at rates of 25 to 40 kilometers per century, with the fastest migration by spruce into northwestern Canada at 200 kilometers per century. Analyses of fossil pollen grains indicate that beech forests moved about 20 kilometers per century, far less than Davis and Zabinski indicate would be necessary to keep pace with climate changes projected for the coming century.
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From page 130... ...
They find that the projects are most likely to succeed when local people participate in the planning and implementation and when the plan itself is both environmentally and economically sound. For example, forest reserves can offer an economic return through sustainable agriculture anct forestry and through gathering of nonwood forest products such as latex, fibers, fruits, nuts, and a host of other miscellaneous products.
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