Transcript Wetlands Power Point - Winona State University

What are wetlands?
• The U.S. Fish and Wildlife Service defines wetlands as the
“…lands transitional between terrestrial and aquatic systems
where the water table is usually at or near the land surface or
the land is covered by shallow water.” (Cowardin et al., 1979)
• Wetlands must have all of the following characteristics:
– Hydrology—presence and duration of water
– Hydric soil—poorly drained and with evidence of low or
fluctuating oxygen
– Hydrophytic vegetation—dominance of vegetation adapted to
saturated soil conditions
Wetland Functions
 The physical, chemical, and biological
interactions within wetlands are often
referred to as wetland functions
 Water filtration and purification
 Trapping sediments and contaminants
 Flood control and stream flow regulation
 Erosion reduction
 Habitat for aquatic and terrestrial plants and animals
Wetland Hydrology
• Area is inundated or saturated to the surface
for at least 5% of the growing season in most
years
– Growing season is based on soil temperature and
is determined for regions by the USDA
– Most years = 51 out of 100 years
Wetlands are NOT always wet!
Hydric Soil
• A soil that is saturated, flooded, or ponded
long enough during the growing season to
develop anaerobic conditions in the root zone
– Tend to be dark in color and have mottles of iron
staining
Function of Hydric Soils
• Transformation of various elements in hydric soils
– Denitrification – NO3-  N2
– Converts sulfates (SO4-2) into sulfides (H2S) and insoluble
complexes with phosphate and metal ions –removes
sulfates caused by anthropogenic activities
– Sequesters C – decomposition of organic material
Hydrophytic Vegetation
• Plant species that are adapted
for life in saturated soils
– Anaerobic soil conditions
– Soggy or waterlogged soils
• Require adaptations for better
support
• Require adaptations for gas
exchange
• Hydrophytes are plants
growing in water or on
substrates that are periodically
deficient in oxygen
Hydrophytes
• Plants classified by tendency to occur in wetlands
– Obligate: Almost always occur in wetlands (>99%)
– Facultative Wetland: Usually occur in wetlands (67-99%)
– Facultative: Equally likely to occur in wetlands or non-wetlands (3367%)
– Facultative Upland: Usually occur in non-wetland (67-99%) but
occasionally in wetlands (1-33%)
– Upland: Almost always occur in non-wetlands (>99%)
Function of Wetland Biota
• Plants reduce the erosive potential of peak flows 
stabilize shorelines and levees
• Produce an abundance of detritus consumption
by commercially important vertebrates and
invertebrates.
Wetland Biota
• Large volume of biomass – commercially
important plants and animals
– 95% of the harvested fish and shellfish species are
wetland dependent
– Wetland timber – about 22 million ha
Plant and Animal Communities
 Wetlands in the United States support
 about 5,000 plant species
 190 species of amphibians
 80% of America’s bird population
 Provide critical habitat
 Wetlands occupy 3.5% of the land area  large
amount of habitat yet a small amount of habitat
Water Storage
 Wetlands are reservoirs for rainwater and runoff
– storm abatement (coastal)
– flood mitigation (riparian)
 Moderate stream flows
 Reduce peak water flows
 Maintain flow during low water
 Help prevent flooding by temporarily storing water
 Recharge groundwater
Water Quality
Water Filtration or Purification
 Remove nutrients, pesticides, metals, and
bacteria from surface waters where they
are absorbed, consumed or broken down
by plants, animals, and chemical
processes within the wetland
 Wetlands are the earth’s kidneys
 Limit eutrophication and pollution of water
bodies
Particulate Removal
 Filter out sediments and particles suspended
in runoff water
 Sediments typically contain adsorbed
nutrients and metals
 Limits siltation
 Reduces Habitat Impacts
Geologic Function of Wetlands
• Anaerobic conditions  exceptional
preservation qualities
– Store pollen, fossils, and human artifacts
– Animals from the last Ice Age were discovered in
bogs.
• Used to reconstruct paleoclimates, animal
evolution, and vegetation type
Kinds of Wetlands
Vary based on geographic location, language, etc.
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Bog – peat-accumulating with no
inflows or outflows; supports mosses
Bottomland – lowlands along
streams and rivers
Fen – ground-water fed; peat
accumulating
Marsh – frequently inundated;
emergent herbaceous vegetation
Mire – peat-accumulating (Europe)
Moor – peat-accumulating (Europe)
Muskeg – Large expanses of
peatlands or bogs (Canada/Alaska)
Peatland – any wetland that
accumulates decaying plant matter
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Playa – marshlike ponds similar to
potholes (southwest U.S.)
Pothole – shallow, marshlike pond;
found in Dakotas and Canada
Reedswamp – marsh dominated by
common reed (Europe)
Slough – swamp or shallow lake
system
Swamp – wetland dominated by
trees or shrubs
Vernal Pool – shallow, intermittently
flooded wet meadow
Wet Meadow – grassland with
waterlogged soil near the surface –
without water for most of year
Wet Prairie – similar to marsh but
water levels intermediate between
marsh and wet meadow
Rookery Bay National Estuarine Research Reserve – Salt Marsh
Mangrove Swamp – Everglades National Park – Estuarine Wetland
Ritchey Woods Natural Area – Riparian Wetland
Point Pelee National Park – Ontario, Canada - Lacustrine
Western US - Palustrine Wetland – in topographic low
Ritchey Woods Natural Area – Forested Wetland
Photo: Marion
Photo: http://www.epa.gov/owow/wetlands/types/vernal.html