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 ForestForests' Retreat: Page 5 The promotion of a commercial approach to old-growth tropical rainforests, even "sustainable yield," is based on fragmentary and inadequate knowledge of these ecosystems. It is not known with certainty that their trees can be harvested without harm. Sustained yield forestry concerns prevention of the extinction of various tree species by controlling harvest and, to a lesser extent, protecting of watershed and soil, but not necessarily ecosystem protection. Maintaining the complex web of plants and animals that form a forest should be the prime consideration in conservation. To this end, protection from harm is the logical approach until these ecosystems are properly understood. Their ecological value will only be measurable as knowledge about their functioning and their role in the world's climate are explored in the future. In economic terms, they have great potential as tourist attractions, and the new videocam Internet business, as described in the Focus on Indonesia section below, will likely far outproduce short-term income from timber or conversion to agriculture.
An indication of the effects of this destruction is the fact that 76 percent of the 1,186 birds in higher categories of threat, or 902 species, are forest‑dwellers, according to Threatened Birds of the World, a comprehensive report by BirdLife International, which examines bird status for the Red Lists of Threatened Species published by the International Union for the Conservation of Nature (IUCN) (BI 2000). All these birds are in danger of extinction. Some, such as the 182 Critical species, are in imminent danger of becoming extinct. Of the 902 forest birds, 93 percent are native to tropical forests; of these, 41 percent are found in lowland forests and 36 percent in montane moist forests, such as cloud forests (BI 2000). Three-fourths of threatened forest birds are dependent on a particular type of forest, and almost half require near-pristine habitat, with little or no disturbance, or habitat degradation (BI 2000). Only 3 percent of threatened forest birds can tolerate habitat modification. Unsustainable selective logging affects 367 forest bird species, while other threats include clearing forests for small farms (24 percent), tree plantations, clearcutting forest, livestock grazing, cutting trees for firewood, mining in forests and human settlements (BI 2000). An additional 727 bird species are classified as Near-threatened or close to qualifying as Threatened.
Likewise, forests are the major habitat for threatened mammals. The IUCN assigned habitat types to 515 (46 percent) of threatened mammals, finding that about 75 percent inhabited tropical rainforest; of these species, 35 percent in lowland and about 22 percent in montane (Hilton-Taylor 2000). (Some mammals may occupy more than one habitat). Tropical dry forest accounts for another 15 percent; tropical degraded forest, 4 percent; and tropical savannah woodland about 5 percent of threatened mammal habitats. By comparison, temperate broadleaf forest is the habitat for some 4 percent; and coniferous forests, 5 percent of threatened mammals (Hilton-Taylor 2000). The vast majority of threatened frogs and toads are also native to tropical forests.
Many species of tropical trees have been driven to extinction by habitat destruction and the exotic wood trade. The majority of Caribbean islands, which were covered in tropical rainforests when Europeans first saw them in the late 15th century, are now barren. A species of mahogany native to the Caribbean (Swietenia mahogani) has been so heavily exploited that no unstunted specimen remains. Elsewhere, once common species of forest plants and animals have been eliminated or endangered. Where habitats were limited on islands such as Hawaii and Mauritius, fragrant sandalwoods and other trees were cleared, and few--if any--specimens remain of the trees that once made up these forests.
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