GM_003

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綜合寫作

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The preservation of forests has become a global concern as woodlands around the world are being rapidly depleted. The focus of environmental efforts has often centered on the thick forests of the tropics. Recently, however, interest has risen in establishing forests in more temperate (moderate climates) parts of the world. In particular, there has been interest in planting shelter forests in areas surrounding cool deserts in the Northern and Southern hemispheres. Environmentalists believe that planting large shelter forests in these temperate zones will benefit both human beings and the environment.

First, shelter forests would benefit farmers by protecting farmland from desertification. Windstorms blow away the fertile topsoil of grasslands that surround deserts; this process gradually depletes land suitable for agriculture. The planting of shelter forests could slow or stop this process. The trees would block the harsh desert winds that blow away topsoil, and their roots would help prevent erosion. Some ecologists think that shelter forests could protect millions of acres of land that would otherwise become unavailable for farmers’ use.

Second, shelter forests would create new habitats for animals. Forests are an important ecosystem, providing a home for many species of animals that cannot live on open plains or grasslands. As forests around the world are gradually cleared, key animal habitats disappear. The planting of artificial forests in otherwise barren areas could partially reverse this global trend, and could help expand the number of animal species greatly.

Third, planting shelter forests in temperate zones would have a positive effect on the global climate. Global warming, a trend in which average global temperatures are increasing, is caused largely by the carbon dioxide gas released by human activities. Since plants absorb carbon dioxide as they grow, new forests contribute to the reduction of atmospheric carbon dioxide levels. Therefore, the large-scale planting of shelter forests would help slow global warming.