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Wetlands Values and Trends
RCA Issue Brief #4
November 1995
Wetlands--a valuable asset
The facts on wetland losses
Regional differences among wetlands
Examples of local projects
Wetlands help us in many ways
Did you know
...that wetlands are often called the "kidneys of the landscape"
since, like kidneys, they filter out harmful materials?
...that migratory birds use different types of wetlands for specific habitat
and nutritional needs during migration? That some birds prefer swamps, while
others prefer potholes? That some stop in wetlands for nesting purposes,
others stop for wintering, and still others stop only for short periods
to refuel or to mate on the way to northern nesting grounds?
...that wetlands in the United States support about 5,000 plant species,
190 amphibian species, and one-third of all bird species?
...that half to two-thirds of America's wild ducks hatch in the prairie
pothole region marshes in North Dakota, South Dakota, Minnesota, and Iowa?
...that wetlands provide habitat for about one-half the fish, one-third
of the birds, one-fourth of the plants, and one-sixth of the mammals on
the U.S. threatened and endangered species lists?
...that from 1982 to 1992, wetland loss occurred at a higher rate in the
East and Southeast than in the Midwest and West, mainly because of development?
...that conversion of wetlands to agricultural uses has slowed dramatically
since the 1970's?
Wetlands--a valuable asset
"Wetlands" describes a variety of areas where plants and animals
especially suited to wet environments can be found. Wetlands are among the
richest and biologically most productive habitats on Earth.
Wetlands occur in many forms, including forested swamps, deep and shallow
marshes, bogs, and prairie potholes. Some wetlands such as deepwater swamps
are always wet, while others, such as bottomland swamps, dry out in certain
seasons. These different types of wetlands have important functions; they
protect shorelines, shelter rare and endangered species of plants and animals,
and are used for recreation and education.
The cleansing power of wetlands provides natural pollution control. Because
wetlands remove nutrients, pesticides, and sediments from surface waters,
they are highly efficient, low-cost alternatives for treating sewage and
animal waste. Many wetlands slow the overland flow of water and thus reduce
flooding and soil erosion downstream. Coastal wetlands help absorb some
of the impact of storm tides and waves before they reach upland areas. Wetlands
are reservoirs for rainwater and runoff. They recharge ground water supplies
and extend streamflow during periods of drought or low rainfall. Both coastal
and inland wetlands provide breeding, nesting, and feeding habitats for
millions of waterfowl, birds, and other wildlife.
Historically, wetlands were thought to be valuable only as sources of peat
and fossil fuels, as sites for fishing and hunting, or as places to drain
for farmland. After wetland scientists and natural resource managers began
to study these vital areas, they discovered that wetlands have significant
economic and ecological importance. In addition to these specific benefits
of wetlands, all the water on our planet constantly moves through the hydrologic
cycle; wetlands, therefore, as key elements in the water cycle, help replenish
our water supply.
Migratory birds follow special routes during migration. These routes are
typically aligned with wetlands crucial to the survival of these birds.
Migratory birds depend on wetlands to provide food, shelter, water, and
breeding and nesting sites. As some of these wetlands disappear, the birds
are forced to modify their flight paths in search of alternative stopover
sites during their journey. Such changes in their flight plan can decrease
their chances of survival and successful reproduction. The prairie pothole
regions of North Dakota, South Dakota, Minnesota, and Iowa have historically
produced up to 75 percent of all waterfowl in the United States in a given
year, largely because of their abundance of small, scattered, highly productive
wetland areas.
The facts on wetland losses
Before European settlement of North America, there were an estimated 220
million acres of wetlands in what is now the contiguous 48 states. About
half that acreage has disappeared, mostly drained for crop production. One
of the first large-scale drainage projects was undertaken by the Dismal
Swamp Drainage Company in Virginia and North Carolina, which employed a
young surveyor named George Washington.
Between 1982 and 1992, nearly 1.6 million acres of wetlands on non-Federal
lands were converted to other uses, according to the 1992 National Resources
Inventory (NRI). These losses--which include 1.4 million acres of wetlands
to uplands and about 200,000 acres of wetlands to deepwater habitat--were
partly offset, however, by gains of nearly 800,000 acres from previously
drained wetlands, uplands, and deepwater habitat over the 10 years, to produce
total net losses of around 800,000 acres.
This figure represents a marked decline in wetland conversions overall,
but the rate of conversions for agriculture has declined much more rapidly
than the conversion rate for other purposes. According to U.S. Fish and
Wildlife Service estimates, agricultural conversions claimed about 398,000
wetland acres annually from the mid-1950's to the mid-1970's, and 157,000
acres a year from the mid-1970's until the mid-1980's. Since then, however,
wetland conversions for agriculture have dropped to about 31,000 acres a
year.
During his administration, President Bush supported a national goal of "no
net loss" of wetlands. President Clinton has called for a long-term
gain in wetlands. The goal of "no net loss" refers to the Nation's
overall wetland base; there must be a balance between wetland losses and
gains in the short run and an increase in wetlands acreage in the long run.
Although we have not achieved that goal, we have clearly moved much closer
to it. The reduction in wetland losses over the past 10 years reflects the
combined effect of several important trends:
- Decline in the profitability of converting wetlands for agricultural
production
- Passage of the Swampbuster provision in the 1985 and 1990 farm bills
- Presence of the Clean Water Act Section 404 permit program and the
growth in state regulatory programs
- Greater public interest and support for wetlands protection and restoration
- Implementation of Federal, State, and local wetlands programs that
protect and restore wetlands, such as USDA's Wetlands Reserve Program, the
U.S. Fish and Wildlife Service's Partners for Wildlife Program, and State
programs such as Reinvest in Minnesota
Achieving "no net loss" and moving into a net gain in wetlands
may be possible if restoration programs such as the Wetlands Reserve Program
are fully funded and there is no reduction in the protection of wetlands
provided by existing programs. However, the greatest wetland losses are
occurring in areas of economic growth; in the presence of strong economic
growth, existing programs are not offsetting losses.
Regional differences among wetlands
EastMillions of acres of drained wetlands are now poor-quality agricultural
land in the East. Agricultural and forest land are being converted to commercial
and residential development. Because of drainage and nonpoint source water
pollution, many wetland and aquatic wildlife species have declined in this
area. Wetlands and riparian areas support a higher diversity and abundance
of wildlife species than other farmland habitats. Landscape changes to this
area have impacted the rate of wetland loss.
SoutheastLess than 60 percent of the original wetlands in the lower
Atlantic Flyway still exist. And the remaining wetlands are declining in
quality because of nutrient loading, altered hydrology, and urban encroachment.
Wetland wildlife species have experienced long-term declines. Loss and degradation
of the south aquatic system and loss of much of the native fauna contribute
to the decline of global biotic diversity.
South CentralThe loss and decreased quality of existing wetlands
and associated upland buffers in areas such as, but not limited to, playas
or seasonal depressional wetlands, saline lakes, and riparian corridors
have resulted in declining wildlife populations. Significant loss and degradation
of Gulf Coast estuaries have occurred because of saltwater intrusion from
canal construction and development, geologic subsidence, and developmental
pressures along the coastal regions. The Playa Lake Joint Venture reports
that protection and improvement of playas in the Southwest are vital to
ensuring continued accommodation of waterfowl and other water birds overwintering
in, migrating through, and breeding in this region.
MidwestAt one time, open prairie wetlands accounted for nearly
one-fourth of the total surface area of the Midwest. However, drainage for
crop production has severely reduced wetland acreage. Most of the wetland
acreage that remains is either forested or degraded. Nearly 60 percent of
the rural land in this region is cropland and pasture. Wetland drainage
and alteration of associated uplands have led to declines in many wetland
wildlife species. Population levels of certain species of waterfowl and
other migratory birds are declining. The recreational and economic impacts
of wetland loss in this area are a major concern.
Northern PlainsThis area, although one of the most altered ecosystems
in the country, is still one of the most ecologically rich regions in the
world. When the most recent glacier retreated, it created the prairie potholes--areas
containing a high density of isolated wetlands interspersed among the short
and tall grass and mixed-grass prairies. This unique combination of habitats
supported the evolution of a great diversity of ground-nesting wildlife,
particularly migratory birds. Prairie potholes are the most important breeding
grounds for waterfowl in North America. Over the years, nearly half of the
original wetlands in the prairie pothole region have been drained. Of those
remaining, most are cropped when the weather permits. Agricultural practices
around the potholes often result in sedimentation and addition of pesticides
and fertilizers, resulting in degraded wetland vegetation, water quality,
and wetland habitats. Runoff from unprotected cropland is slowly filling
many of these wetlands with sediment.
WestLivestock grazing is the most prevalent agricultural use in
this area. Fifty-nine percent of the original wetlands have been lost throughout
the region. Losses of wetlands in arid areas are particularly detrimental
to wildlife. Wetlands in California's Central Valley have been reduced from
more than 4 million acres to about 300,000 acres. The natural annual flood
cycle of the remaining Central Valley wetlands was eliminated by flood control
and water-development projects. Consequently, the wetlands must be managed
by artificial and intentional flooding with scarce, expensive water. Seventy
percent of these remaining wetlands are privately owned.
Examples of local projects
The Beaver Creek Project in Clarion County, Pennsylvania, is a wetlands
project that not only provides wildlife habitat, but also serves as a fisheries
resource, offers recreational opportunities, and provides a natural setting
for an outdoor learning center. Nine small lakes have been built, totaling
70 acres. All the lakes have been stocked with bass and bluegill and produce
a variety of aquatic plants such as wild celery, duck potato, and buttonrush.
These plants can be harvested and transplanted to other wetlands for wildlife
food and to help restore water quality. Several waterfowl species have had
great nesting success. A larger lake will also be constructed for use as
a water source for western Clarion County. With all these benefits of the
project, everyone wins!
For 20 years, a South Dakota farmer had been farming atop a geologic formation
left by the last glacier 10,000 years ago. The area was one of profuse wetlands
and tallgrass prairie. The farm produced livestock, wheat, corn, and an
abundance of wildlife. The farmer restored more than 30 previously drained
wetlands, resulting in at least 120 surface acres of water. The wetlands
are the centerpiece of the farm, providing habitat for shorebirds, waterfowl,
and dozens of other species. The farmer has also planted more than 800 acres
of adjacent cropland to perennial grasses and legumes to reduce sedimentation
and nutrient loading in the wetlands.
Various other individual state and local projects committed to restoring
wetlands include:
- Pickerel Creek Wetland Restoration Project, which involves 2,100 acres
in four wetlands at an average depth of 2 feet, completed in 1993 by the
Ohio Department of Natural Resources, Ducks Unlimited, and the Natural Resources
Conservation Service
- Riparian wetland restored in California by the Nature Conservancy
and the Natural Resources Conservation Service
- Creation of wetlands by Missouri farmers in cooperation with the Butler
County Soil and Water Conservation District and the Natural Resources Conservation
Service
- Restoration of wetlands in the Lake Michigan watershed, Ozaukee County,
Wisconsin, by the local conservation district, the U.S. Fish and Wildlife
Service, the Wisconsin Department of Natural Resources, Ducks Unlimited,
and the Natural Resources Conservation Service
Wetlands help us in many ways
More than half of all adults (98 million people) in the United States hunt,
fish, bird-watch, or photograph wildlife. These activities, which rely in
large measure on healthy wetlands, provided an estimated $59.5 billion to
the national economy in 1991. Individual states gain economic benefits from
recreational opportunities in wetlands that attract visitors from other
states.
Wetlands also yield fish; they are important spawning and nursery areas
and provide plant food for commercial and recreation fish and shellfish
industries. In 1991, the dockside value of fish landed in the United States
was $3.3 billion. The U.S. fish processing and sales industry generates
nearly $27 billion a year and employs hundreds of thousands of people. An
estimated 71 percent of this value is derived from fish species that depend
directly or indirectly on coastal wetlands during their life cycles. For
example, Louisiana's marshes alone produce an annual commercial fish and
shellfish harvest of 1.2 billion pounds--worth $244 million in 1991.
Wetlands improve water quality by keeping nutrients, sediments, and other
materials from entering lakes, streams, and reservoirs. For example, bottomland
hardwood wetlands in South Carolina remove sediment and toxic substances
and remove or filter excess nutrients. Scientists estimate that the least-cost
substitute for these wetlands benefits would be a water treatment plant
costing $5 million (in 1991) to construct; additional money would be needed
to maintain and operate the plant.
Wetlands often function like natural tubs or sponges, storing water (floodwater,
or surface water that collects in isolated depressions) and slowly releasing
it. Trees and other wetland vegetation help slow floodwaters. This combined
action, storage and slow release, can lower flood heights and reduce the
water's erosive potential. Wetlands thus--
- reduce the likelihood of flood damage, thereby protecting crops in
agricultural areas and protecting roads, buildings, and human health and
safety in developed areas;
- help control increases in the rate and volume of runoff in urban areas;
- buffer shorelines against erosion;
- help maintain and stabilize streamflows over longer periods of time;
- provide spawning grounds and habitat for commercially important fish
and shellfish;
- provide habitat for rare, threatened, and endangered species of plants
and animals;
- help preserve biological diversity across the landscape; and
- trap sediments, nutrients, and other pollutants, thereby greatly improving
water quality.
Wetlands conservation is one of the most important and sensitive natural
resource issues in our country today. Wetlands are important because they
have unique functions and values. Because wetlands are so productive and
greatly influence the flow and quality of water, they are valuable to everyone.
Destruction of wetlands can lead to serious consequences, such as increased
flooding, extinction of species, and decline in water quality. We can avoid
these consequences by maintaining the valuable wetlands we have and restoring
wetlands where possible.
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