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Comparison of Natural and Human-made Wetlands
Quick review
Common wetland features:
Wet at least part of the year
Water level is at or near the surface
Soils are often saturated with water
Home to specialized organisms that are
adapted to wet conditions
What are wetlands?
Wetlands are like transitional zones. They’re not
as wet as lakes, but they’re not “dry ground”
either. They’re somewhere in-between.
Image source: http://www.dem.ri.gov/programs/benviron/water/wetlands/whatis.htm
Wetlands are valuable
Wetlands support life!
High biodiversity
Critical habitat for many endangered species
Wetlands are valuable
Humans benefit of wetlands:
Water purification
Groundwater recharge
Protection from storms and floods
Prevention of erosion
Aesthetic values (scenery, wildlife viewing)
Wetland losses
About ½ of the wetlands originally in the
U.S. have been drained or filled
Agriculture
Roads and railways
Urbanization
Wetland losses
Since wetlands are flat, they were
historically thought to be better-suited for
farmlands
Wetlands were considered “wastelands”
Wetlands impeded transportation routes
Many people were afraid of wetlands!
Current opinions of wetlands
Now they are valued for the many benefits
they provide
Draining or filling is now illegal without
proper permits
Even with permits, new wetlands must
often be constructed to compensate
“Wetland mitigation”
Wetland mitigation
Process of creating new wetland
ecosystems
Two common options:
Construct new wetlands where wetlands
never existed before
Restore wetlands in an area where they used
to exist in the past
Wetland mitigation
Process is overseen by State and Federal
agencies, to ensure that permit
requirements are met U.S. Environmental Protection Agency (EPA)
Michigan Department of Environmental Quality
(MDEQ)
Wetland mitigation
Our research question: How do human-
made wetlands compare to natural ones?
Hydrology
Soils
Vegetation
What the research says
It’s hard to build wetlands!
Mother Nature appears to do a better job
than us
Challenges of creating/restoring wetlands: Re-creating natural hydrology (water characteristics)
of wetlands
Keeping exotic plant species away
Developing rich, organic soils
Problem: Improper hydrology
Too wet! This is basically a pond, not a wetland.
Problem: Improper hydrology
Too dry! This is basically a grassland, not a wetland.
Problem: Exotic plant species
Phragmites australis
Melilotus alba
Problem: Organic-poor soils
Wetland mitigation
Despite challenges, many “good” wetlands
have been created or restored
Even marginal-quality wetlands can offer
benefits to wildlife and people
Over time, human-made wetlands can
begin to look more like natural wetlands
Our field exercise
Examine human-made wetlands in our
area and compare to the natural ones
we’ve studied already
How are they similar? How are they different?
Hydrology, vegetation, soils
Our research question: How do human-made
wetlands compare to natural ones?
Any questions?
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