Types of Wetlands - US EPA · S WAMPS are fed primarily by surface water inputs and are dominated...

MARSHES are periodically saturated,flooded, or ponded with water and charac-

terized by herbaceous (non-woody) vegetationadapted to wet soil conditions. Marshes are

further characterized as tidal marshesand non-tidal marshes.

Tidal (coastal) marshes occur alongcoastlines and are influenced by tidesand often by freshwater from runoff,rivers, or ground water. Salt marshesare the most prevalent types of tidalmarshes and are characterized by salt-tolerant plants such as smooth cord-grass, saltgrass, and glasswort. Saltmarshes have one of the highest rates of

primary productivity associated withwetland ecosystems because of theinflow of nutrients and organicsfrom surface and/or tidal water.Tidal freshwater marshes are locatedupstream of estuaries. Tides influencewater levels but the water is fresh.The lack of salt stress allows agreater diversity of plants to thrive.Cattail, wild rice, pickerelweed,and arrowhead are common andhelp support a large and diverserange of bird and fish species,among other wildlife.

Nontidal (inland) marshes aredominated by herbaceous plantsand frequently occur in poorlydrained depressions, floodplains,and shallow water areas along theedges of lakes and rivers. Majorregions of the United States thatsupport inland marshes include theGreat Lakes coastal marshes, theprairie pothole region, and theFlorida Everglades.

Do you think all wetlands are the same? Think again. Eachwetland differs due to variations in soils, landscape,climate, water regime and chemistry, vegetation, andhuman disturbance. Below are brief descriptions of themajor types of wetlands found in the United Statesorganized into four general categories: marshes, swamps,bogs, and fens.

! Freshwater marshes are characterized byperiodic or permanent shallow water, littleor no peat deposition, and mineral soils.They typically derive most of their waterfrom surface waters, including floodwaterand runoff, but do receive ground waterinputs.

! Wet meadows commonly occur in poorlydrained areas such as shallow lake basins,low-lying depressions, and the landbetween shallow marshes and upland areas.Precipitation serves as their primary watersupply, so they are often dry in the summer.

! Wet prairies are similar to wet meadowsbut remain saturated longer. Wet prairiesmay receive water from intermittentstreams as well as ground water andprecipitation.

! Prairie potholes develop when snowmeltand rain fill the pockmarks left on thelandscape by glaciers. Ground water inputis also important.

! Playas are small basins that collect rainfalland runoff from the surrounding land.These low-lying areas are found in theSouthern High Plains of the United States.

! Vernal pools have either bedrock or a hardclay layer in the soil that helps keep waterin the pool. They are covered by shallowwater for variable periods from winter tospring, but may be completely dry for mostof the summer and fall.

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United States Office of Water EPA 843-F-01-002bEnvironmental Protection Office of Wetlands, September 2001Agency Oceans and Watersheds (4502T)

Many vernal pools fill with water infall or spring.

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Freshwater marshes, like this one inSequoia National Park, are dependenton rainfall, runoff, and seasonalflooding for their water supplies.

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Farmland surrounds these prairiepotholes in Nebraska.

SWAMPS are fed primarily by surface waterinputs and are dominated by trees and

shrubs. Swamps occur in either freshwater orsaltwater floodplains. They are characterized byvery wet soils during the growing season andstanding water during certain times of the year.Well-known swamps include Georgia’s Oke-fenokee Swamp and Virginia’s Great DismalSwamp. Swamps are classified as forested,shrub, or mangrove.

Forested swamps are found in broadfloodplains of the northeast, southeast, and

south-central United States andreceive floodwater from nearbyrivers and streams. Commondeciduous trees found in these areasinclude bald cypress, water tupelo,swamp white oak, and red maple.

Shrub swamps are similar toforested swamps except thatshrubby species like buttonbush andswamp rose dominate.

Mangrove swamps are coastal wetlands char-acterized by salt-tolerant trees, shrubs, and otherplants growing in brackish to saline tidal waters.

These tropical and subtropical systems have aNorth American range that extends from the south-ern tip of Florida along the Gulf Coast to Texas.

BOGS are freshwater wetlands characterizedby spongy peat deposits, a growth of ever-

green trees and shrubs, and a floor covered by athick carpet of sphagnum moss. These systems,whose only water source is rainwater, areusually found in glaciated areas of the northernUnited States. One type of bog, called apocosin, is found only in theSoutheastern Coastal Plain.

On the InternetEPA’s Wetland Home Page contains information and pictures on several

types of wetlands ...................................................................................................... www.epa.gov/owow/wetlands/types

Types of Wetlands and Their Roles in the Watershed, part of North CarolinaState University’s WATERSHEDSS ...................................................... h2osparc.wq.ncsu.edu/info/wetlands/types3.html

Wetlands of the United States from the USGS Northern PrairieWildlife Research Center ........................................................... www.npwrc.usgs.gov/resource/1998/uswetlan/types.htm

Prairie Potholes .................................................................................. www.greatplains.org/resource/1999/ppjv/ppjv.htm

In PrintWetlands. 3rd Edition. W.J. Mitsch, and J.G. Gosselink. 2000. John Wiley & Sons, Inc. New York, NY.

In Search of Swampland: A Wetland Sourcebook and Field Guide. R.W. Tiner, 1998. Rutgers University Press, Piscataway, NJ.

Adopting a Wetland—A Northwest Guide. S. Yates. 1989.

FENS are groundwater-fed peat-

forming wetlandscovered by grasses,sedges, reeds, andwildflowers. Willowand birch are alsocommon. Fens, likebogs, tend to occur inglaciated areas of thenorthern UnitedStates.

The Wetland Fact Sheet Series

Wetlands Overview Funding Wetland Projects

Types of Wetlands Wetland Monitoring & Assessment

Functions & Values of Wetlands Sustainable Communities

Threats to Wetlands Volunteering for Wetlands

Wetland Restoration Teaching about Wetlands

For more information, visit www.epa.gov/owow/wetlands.

American Avocet

Bog ecosystemssupportcranberries,blueberries, andcarnivorousplants like thepitcher plant.

Trees found inswamps are some-times buttressed atthe base, whichhelps anchor them inthe saturated soils.

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Forested swamps serve acritical role in the water-shed by reducing the riskand severity of floodingto downstream areas.