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Betreff: INFOTERRA: Do Mitigated Wetlands Really Work Only Time Will Tell.
Absendedatum: Mon, 6 Mar 2000 14:23:50 -0500
Antworten an: "Karen Claxon" <kclaxon@earthlink.net>
Do Mitigated Wetlands Really Work? Only Time Will
Tell.http://www.acs.ohio-state.edu/units/research/archive/wetlands.htm
2/16/00
DO MITIGATED WETLANDS REALLY WORK? ONLY TIME WILL TELL
COLUMBUS, Ohio - Are man-made wetlands really as good as the real thing?
It's going to take scientists more than a dozen years to find out, according
to a researcher at Ohio State University.
Ohio State's two experimental wetlands seem to be behaving quite
differently -- one is 20 percent more productive than the other, but is far
less diverse in terms of plant species. But both seem to contribute equally
to reducing nitrates -- chemicals often found in pesticides.
"Right now, it seems to be a question of choosing between diversity vs.
productivity when constructing a wetland," said William Mitsch, a professor
of natural resources at Ohio State and the director of the Olentangy River
Wetlands Research Park.
Mitsch presented six years of wetlands research Feb. 19 in Washington, D.C.
at the annual meeting of the American Association for the Advancement of
Science.
Six years ago, Mitsch and several volunteers planted about
a dozen plant species in one two-and-a-half acre wetland, while letting
nature develop the other equally sized wetland. "The unplanted wetland is
now producing more biomass," he said. "It produces more peat, which
translates to more vegetation, which means denser habitat for wildlife to
conceal themselves." Also, more peat may impact the ability of the wetland
to filter pollutants.
Three years into the experiment, the wetlands had converged -- they were
nearly identical in terms of plant species and water filtration. Since then,
they have diverged in terms of vegetation. The originally unplanted wetland
is now filled with mostly cattails and bulrushes, while the other wetland
has about a half-dozen plant species. Yet many of the functions, such as
water purification, are similar in both wetlands.
"That's why we're waiting 14 more years," Mitsch said. "We want to see if
the wetlands converge again or whether the difference in productivity is
enough to cause them to diverge in their ability to clean water."
Though Mitsch admits that he is unsure where the wetlands are headed, he
agrees that time is of the essence, as real estate developers continue to
fill in natural wetlands and environmental problems -- such as hypoxia --
seem to worsen.
When a developer fills in and builds on a natural wetland, he's required by
federal law to create a wetland in a nearby area -- a process called
mitigation. And it's the developer's responsibility to maintain and monitor
the wetland for five years, according to Mitsch. After five years, though,
these mitigated wetlands often "disappear off everybody's radar screen."
"And the Army Corps of Engineers wants to know if, after five years, a
created or restored wetland functions as a real wetland," Mitsch said. "We
just can't draw that conclusion yet."
But scientists do know that it will take a phenomenal amount of land --
about 5 million acres -- to create enough wetlands to control the
environmental threat of hypoxia in the Gulf of Mexico. Essentially, hypoxia
is the depletion of oxygen from a body of water, turning the area into a
"dead zone." Each spring, nearly 7,000 square miles of water in the Gulf of
Mexico become a dead zone.
"The ability to create wetlands provides a marvelous opportunity to solve an
enormous environmental problem, and to solve it ecologically, rather than
mechanically," Mitsch said.
Wetlands are often called the "kidneys" of the landscape. They act as buffer
zones, reducing the amount of nitrates and other chemicals in water. "And
wetlands do this at a tenth of the cost of a water treatment plant," Mitsch
said.
Wetlands also serve as a zoo of sorts. "They allow the public to view nature
in a real setting, again at a tenth of what it would cost to build an actual
zoo," he said.
One of the biggest problems with creating wetlands, however, is a lack of
education. "Many of the people creating and restoring wetlands aren't
formally trained to do so," Mitsch said. He suggests making it mandatory
that all wetland scientists receive certification in wetland science before
undertaking wetland creation and restoration.
Mitsch conducts much of the wetlands project research at the Olentangy River
Wetlands Research Park with Virginie Bouchard, a postdoctoral researcher in
natural resources at Ohio State. Mitsch, his colleagues and students also
conduct regular tours of the wetlands.
#
Contact: William Mitsch, (614) 292-9774; Mitsch.1@osu.edu
Written by Holly Wagner, (614) 292-8310; Wagner.235@osu.edu
Editor's note: Mitsch chaired a federal committee that released a report
investigating what could be done to stop the flow of nitrates from
Midwestern farm fields into the Gulf of Mexico. Wetlands topped the list of
alternatives that would allow farming in the Midwest to continue close to
how it is practiced today. For a copy of the latest report, contact Don
Pryor, President's Office of Science and Technology, at
donald_pryor@ostp.eop.gov, or Don Scavia, of the National Oceanic and
Atmospheric Administration, at dscavia@noaa.gov.
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