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 ForestForests' Retreat: Page 1 Forest destruction is often gradual, a whittling away by settlers and farmers who destroy portions of forest to grow crops using “slash-and-burn,” in which trees are cut, set afire, and the ashes are used as fertilizer for subsistence agriculture. In tropical forests, the thin soil is fertile for only a few years, and farmers move on to clear more forests. When human populations are very small, as in the case of the native peoples of many tropical forests, their effects are not severe or permanent, as the forest grows back. Non-indigenous people, however, often remove forest cover permanently. They do not think of the forest as a source of life, providing food and protection, as native peoples do. The entire center of the 1,000-mile-long island of Madagascar, once a verdant paradise with giant trees and teeming with wildlife, is now a moonscape as a result of such misuse of the land. Millions of rural people in developing countries now depend on wood cut in local forests for fuel. This has been another major factor in deforestation because of the growth of human populations spreading into new regions, cutting trees and clearing away vegetation.
In the Caribbean, Europe, eastern North America, North Africa and West Asia, most of the original forest cover was destroyed prior to modern times. These forests will not return once cut, nor will their diversity. The ecology and diversity of the forests that once covered much of Europe and the eastern United States will remain unknown because they were cut prior to any biological studies. We have only descriptions of giant trees and the wildlife that inhabited these forests. In the temperate rainforests of the Pacific Northwest, however, biologists are studying the last 5 percent that survives of these magnificent, old-growth forests. Working in the canopies hundreds of feet above the forest floor, they are making new discoveries about these ecosystems. They have learned that lichens colonize only the oldest forests and are key to fixing nitrogen (Moffett 1997), or converting this essential gas into compounds that can be used in forming life-sustaining amino acids and proteins (Franck and Brownstone 1992). One forestry student who climbed a 2,000-year-old Sequoia found cones growing only on the outer branches, which can remain on the tree for as long as two decades; a rich variety of lichens grows on trunks and branches (Moffett 1997). Such discoveries illustrate the importance of preserving these ancient forests.
Only a little more than a century ago, rainforest and temperate old- growth forest covered millions of square miles in West Africa, Central and South America, Southeast Asia, Australia and the western United States. Early settlers, followed by commercial loggers and large-scale livestock and agricultural interests, permanently destroyed these complex ecosystems. In some areas, second-growth forest or shrub has replaced them. Only in Amazonia, Central Africa, Russia and northern Canada do large tracts of virgin forest remain, and these are now being logged by international corporations.
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