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  3. Wetlands What are wetlands? Wetlands can be thought of as "biological supermarkets." They provide great volumes of food

Wetlands What are wetlands? Wetlands can be thought of as "biological supermarkets." They provide great volumes of food

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问题                              Wetlands
    What are wetlands?
    Wetlands can be thought of as "biological supermarkets." They provide great volumes of food that attract many animal species. These animals use wetlands for part of or all of their life-cycle. Dead plant leaves and stems break down in the water to form small particles of organic material called "detritus." This enriched material feeds many small aquatic (水生的) insects, shellfish, and small fish that are food for larger predatory (食肉的) fish, reptiles, amphibians (两栖动物),  birds, and mammals.
    What are the functions and values of wetlands?
    Long regarded as wastelands, wetlands are now recognized as important features in the landscape that provide numerous beneficial services for people and for fish and wildlife. Some of these services, or functions, include water quality improvement, floodwater storage, fish and wildlife habitat, aesthetics, and biological productivity.  These beneficial services, considered valuable to societies worldwide, are the result of the inherent and unique natural characteristics of wetlands.
    Water storage. Wetlands function like natural tubs or sponges, storing water and slowly releasing it. This process slows the water’s momentum and erosive potential, reduces flood heights, and allows for ground water recharge, which contributes to base flow to surface water systems during dry periods. Although a small wetland might not store much water, a network of many small wetlands can store an enormous amount of water. The ability of wetlands to store floodwaters reduces the risk of costly property damage and loss of life--benefits that have economic value to us. For example, the U. S. Army Corps of Engineers found that protecting wetlands along the Charles River in Boston, Massachusetts, saved ＄17 million in potential flood damage.
    Water filtration. After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor.  Nutrients from fertilizer application, manure, !caking septic tanks, and municipal sewage that are dissolved in the water are often absorbed byplant roots and microorganisms in the soil. Other pollutants stick to soil particles. In many cases, this filtration process removes much of the water’s nutrient and pollutant load by the time it leaves a wetland. Some types of wetlands are so good at this filtration function that environmental managers construct similar artificial wetlands to treat storm water and wastewater.
    Biological productivity. Wetlands are some of the most biologically productive natural ecosystems in the world, comparable to tropical rain forests and coral reefs in their productivity and the diversity of species they support. Abundant vegetation and shallow water provide diverse habitats for fish and wildlife. Aquatic plant life flourishes in the nutrient-rich environment, and energy converted by the plants is passed up the food chain to fish, waterfowl, and other wildlife and to us as well. This function supports valuable commercial fish and shellfish industries.
    Fish and wildlife habitat. More than one-third of the United States’ threatened and endangered species live only in wetlands, and nearly half use wetlands at some point in their lives. Many other animals and plants depend on wetlands for survival.
    For many animals and plants, like wood ducks and swamp rose, inland wetlands are the only places they can live. For others, such as black bear, raccoon (浣熊), and deer, wetlands provide important food, water, or shelter. Many of the U. S. breeding bird populations--including ducks, geese, woodpeckers, hawks, and many song-birds--feed, nest, and raise their young in wetlands. Migratory waterfowl use coastal and inland wetlands as resting, feeding, breeding, or nesting grounds for at least part of the year.
    Recreation and aesthetics.  Wetlands have recreational, historical, scientific, and cultural values. More than half of all U.S. adults hunt, fish, bird watch or photograph wildlife. They spend a total of ＄59.5 billion annually. Painters and writers continue to capture the beauty of wetlands on canvas and paper, or through cameras, and video and sound recorders. Others appreciate these wonderlands through hiking, boating, and other recreational activities. Almost everyone likes being on or near the water; part of the enjoyment is the varied, fascinating life forms.
    How are wetlands protected?
    The federal government protects wetlands through regulations, economic incentives and disincentives, cooperative programs, and acquisition.
    Beyond the federal level, a number of states have enacted laws to regulate activities in wetlands, and some counties and towns have adopted local wetlands protection ordinances (法令) or have changed the way development is permitted. Most coastal states have significantly reduced losses of coastal wetlands through protective laws. Few states, however, have laws specifically regulating activities in inland wetlands, although some states and local governments have non- regulatory programs that help protect wetlands.
    Recently, partnerships to manage whole watersheds have developed among federal, state, tribal, and local governments; nonprofit organizations; and private landowners. The goal of these partnerships is to implement comprehensive, integrated watershed protection approaches.  A watershed approach recognizes the inter-connectedness of water, land, and wetlands resources and results in more complete solutions that address more of the factors causing wetland degradation. The government achieves the restoration of former or degraded wetlands under the Clean Water Act Section 404 program as well as through watershed protection initiatives. Together, partners can share limited resources to find the best solutions to protect and restore America’s natural resources.
    While regulation, economic incentives, and acquisition programs are important, they alone cannot protect the majority of our remaining wetlands. Education of the public and efforts in conjunction with states, local governments, and private citizens are helping to protect wetlands and to increase appreciation of the functions and values of wetlands. The rate of wetlands loss has been slowing, but we still have work to do. You can be a part. Approximately 75 percent of wetlands are privately owned, so individual landowners are critical in protecting these national treasures.
    What can you do?
    Despite the efforts of governments and private conservation organizations, pressures that destroy wetlands will continue. The problems of degradation of wetlands from pollution, urban encroachment, groundwater withdrawals,  partial drainage,  and other actions also require attention.
    Many opportunities exist for private citizens, corporations, government agencies, and other groups to work together to slow the rate of wetland loss and to improve the quality of our remaining wetlands.  First, state and local governments need to be encouraged to establish programs to effectively protect wetlands, especially inland wetlands, within their borders. Second, because individual landowners and corporations own many of the nation’s wetlands, they are in a key position to determine the fate of wetlands on their properties. Finally, all citizens, whether or not they own wetlands, can help protect wetlands by supporting wetlands conservation initiatives.
    Wetlands are an important part of our national heritage. Our economic well-being and quality of life largely depend on our nation’s wealth of natural resources, and wetlands are the vital link between our land and water resources. As wetlands are lost, the remaining wetlands become even more valuable.  We have already lost many of our nation’s wetlands since America was ’first settled. We must now take positive steps to protect wetlands to ensure that the functions and related values they provide will be preserved for present and future generations.
The beneficial functions of wetlands, considered valuable to societies worldwide, are the result of the inherent and unique______.
选项
答案natural characteristics of wetlands.
解析 文章在“What are the functions and values of wetlands?”一段中说道：“These beneficial services，considered valuable to societies worldwide，are the result of the inherent and unique natural characteristics of wetlands．”从而得出答案为：natural characteristics of wetlands。
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