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Creating Wetlands
| Article
# : |
17599 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
7 / 1990 |
1,954 Words |
| Author
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Dwight G. Smith
Dwight G. Smith is professor and chairman of the biology
department at Southern Connecticut State University in New
Haven. His latest book, Plants, was released this summer by
Pearson Publishing Company of Boston. |
Humans are creatures of the land - and secondarily of the water. Yet many of the most productive ecosystems are found at the interface of land and water. With a fixed mind-set, modern man has sought to convert the underappreciated wetlands into either water, by dredging, or preferably land, by filling or draining.
Therefore, by meeting the needs of the United States, wetlands are presently disappearing from the 48 conterminous states at a rate of about 400,000 acres per year. Since European settlement of North America began, it is estimated that for the 48 conterminous states about 100 million acres, one half of the original total wetlands, have been converted to a "better" use.
The major cause of wetland destruction has been, and continues to be, the draining of swamps and marshes for farmland. Today the conversion of wetlands into farmland accounts for some 87 percent of the annual total amount of wetlands lost, while urban development, transportation, and various commercial enterprises account for the remainder.
Coastal wetlands have been among the primary targets of development, especially urbanization. In Florida, California, and New Jersey, industrial parklands and ambitious condominium projects continue to erode the remaining tidal marshes.
By comparison, the creation of replacement wetlands has simply not kept pace with their destruction, a problem exacerbated because most of the wetlands created as compensation are not hydrologically and ecologically equivalent to the lost wetlands. Refa Barbour, a transportation engineer with Strand Associates, an environmental consulting company in Madison, Wisconsin, studied the impact of highway construction on wetlands along the Indians interstate system. He found that 101 wetlands totaling 1,044 acres had been destroyed or modified, while 151 new wetlands totaling 638 acres had been created. However, most of the created wetlands were water-filled borrow pits adjacent to the highway, hardly similar to the freshwater marshes and forested wetlands that had been lost. Similar disparities are evident in other regions.
Ralph Tiner of the U.S. Fish and Wildlife service tallied recent wetland losses and gains in Pennsylvania and southeastern Massachusetts. Both areas experienced a net loss of wetlands, mostly marshes and swamps, due to human-induced changes such as channelization, pond construction, and urban development. Net gains of certain types of wetlands - farm ponds in
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