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What
are Wetlands?
Wetlands
are unique and varied ecosystems. An old farm adage,
"too thick to drink and too thin to plow,"
gives a hint both of the nature of wetlands and
the lack of value attributed to them in the past.
But thanks to the work of scientists and conservationists,
we now know how to define wetlands and understand
the important functions they provide.
The
Great Lakes Basin is fortunate to contain a diversity
of wetland types ranging from broad expanses of
coastal marsh to small isolated bogs. Although each
wetland is unique, they share three interrelated
characteristics: 1) The presence of water at or
near the land surface for a long enough portion
of the year to influence the type of vegetation
that can grow there; 2) The presence of plants adapted
to living in soils saturated with water (hydrophytic
- or water-loving - vegetation); and 3) The presence
of distinctive soil types which develop under saturated
conditions (hydric soils).
Marsh
When people hear the term wetland, they most commonly
think of a marsh. Marsh is a term that represents
a broad array of wetlands that are dominated by
grass-like vegetation such as rushes, sedges, and
cattails. They are wet areas that can be periodically
covered by standing or slow-moving water and are
usually associated with ponds, rivers, streams,
inland lakes, and the Great Lakes.
Swamp
Swamps provide very important habitat for a wide
array of wildlife throughout the year. Swamp is
simply the technical term for a wooded wetland.
The soils in swamps are usually rich in nutrients
and are generally saturated periodically at some
point during the growing season.
Bogs
and Fens
Although different in their water chemistry and
source, bogs and fens are often grouped into a broad
category called northern peatlands. Bogs are isolated
from ground and surface water and contain acidic
waters. Fens receive water that has passed through
mineral soils rich in limestone and therefore contain
somewhat alkaline waters. Both bogs and fens contain
plants that are uniquely adapted to their water
chemistry and occur as thick peat deposits in old
lake basins or as blankets of peat across the landscape.
Why
are Wetlands Important?
Historically, wetlands were seen as areas that were
better drained or filled. In a classic example of
"you don’t know what you’ve got ‘til it’s gone,"
we have come to understand wetlands as ecologically
important and complex systems only after many wetlands
have been lost. Billions
of dollars are spent each year in the Great Lakes
Basin on hunting, fishing, birdwatching, hiking,
and camping activities that rely directly on the
creatures that call wetlands home.
Wetlands:
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Wetlands
Provide Fish and Wildlife Habitat
Wetlands provide critical habitat for fish and wildlife.
Nearly all fish in the Great Lakes Basin directly
rely on wetlands for spawning, feeding, or taking
cover. Waterfowl and other birds, and a wide range
of mammals forage, reproduce, and find shelter in
wetlands. More than one-third of all threatened
or endangered animal species in North America depend
on wetland areas.
Wetlands
Protect Water Quality
Wetlands act as living filters that remove pollutants,
nutrients, and sediments from surface water and
ground water. By protecting water quality, wetlands
keep our lakes, streams, and ground water healthy
and support the wide range of uses that rely on
clean water.
Wetlands
Contribute to our Water Supply
Wetlands are usually found where the ground water
table reaches or is close to the land surface. They
are often sites of springs or seeps where ground
water is discharged and are very important for providing
high quality water for our lakes and streams. Because
wetlands store water and release it slowly, they
play an important role in maintaining flow in streams.
In addition, some wetlands are found where water
seeps back into the earth and recharges ground water,
providing a source of clean drinking water. The
water recharge potential of a wetland varies according
to a variety of factors, including wetland type,
geographic location, subsurface geology, soil type,
and amount of precipitation.
Wetlands
Protect Shorelines and Control Erosion
In their natural condition, wetlands associated
with rivers and lakes function as a barrier to erosion.
The root systems of wetland plants stabilize soil
at the water’s edge and enhance soil accumulation
at the shoreline.
Wetland
vegetation along shorelines reduces erosion by dampening
wave action and slowing the speed of water currents.
When wetland and shoreline vegetation is removed,
efforts to control erosion and sedimentation can
be expensive and usually result in further degradation
of fish and wildlife habitat.
Wetlands
Protect Us from Floods
Wetlands act as sponges, temporarily storing flood
waters and releasing them slowly, thus reducing
flood peaks and protecting downstream property owners
from flood damage. Wetlands and adjacent floodplains
often form natural floodways that convey flood waters
from upland to downstream points. These functions
become increasingly important in urban areas where
development has increased the rate and volume of
stormwater runoff. Each year, many communities that
have suffered extensive wetland loss experience
severe flooding.
Wetlands
Contribute to Food and Fiber Production
In addition to the revenue generated from wetlands
by hunting, fishing, and trapping wildlife, wetlands
provide a variety of natural products including
blueberries, cranberries, and wild rice. Wetland
grasses are hayed in many places for winter livestock
feed. Forested wetlands, such as cedar swamps, can
provide sustainable yields of valuable timber if
harvested with careful management and planning.
However, commercial activities, such as peat mining,
logging, livestock grazing, and cranberry cultivation
can severely degrade wetlands and a majority of
their functions if not conducted on a small scale
with the utmost of care.
Education
and Research
Wetlands serve as wonderful outdoor classrooms,
providing excellent opportunities for discovery
and living examples of nearly all ecological principles.
Boardwalks and observation platforms have been constructed
in many wetlands across the Great Lakes Basin to
facilitate educational activities.
A
Valuable, Yet Threatened, Resource
Although the functions that wetlands provide make
them our most valuable landforms, the United States
and Canada have lost alarming amounts of wetland
habitats.
According
to a study by the U.S. Fish and Wildlife Service,
the lower 48 states have lost over 53% of their
original wetlands. Great Lakes states and the province
of Ontario have fared worse - it’s estimated that
only 30% of the original wetlands remain in the
Great Lakes Basin.
There
have been no comprehensive studies to document and
assess the overall ecosystem impacts of these significant
wetland losses. However, one needs only to consider
the increases in flood damage, the degraded or impaired
lakes and rivers, the number of threatened and endangered
species, and myriad other indicators of poor ecosystem
health to get an idea of the impacts.
To this
day, wetlands continue to be degraded or converted
to other uses. Each year, government agencies receive
dredging and filling permit or zoning applications
to authorize activities that degrade wetlands in
the Great Lakes Basin. The vast majority of these
permits or zoning applications are issued. On top
of this intense pressure, there are numerous other
activities that degrade wetlands with little or
no regulatory oversight, including drainage projects,
polluting wetlands with contaminated runoff, and
land clearing and logging.
These
continued threats to Great Lakes wetlands underscore
the critical importance of citizen involvement in
protecting them.
Prepared
in February 2004 by Tip of the Mitt Watershed Council
for the Great Lakes Aquatic Habitat Network and
Fund, a project of the
Tip of the Mitt Watershed Council. Funding provided
by E.P.A. Great Lakes Grants Program, National Fish
and Wildlife Foundation,
and U.S. Environmental Protection Agency.
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