Editing Wetland (section)

==Definitions and terminology==
[[File:A somewhat smoggy Midtown Manhattan skyline as seen from Jamaica Bay - panoramio (cropped).jpg|thumb|300px|[[Marshlands]] are often noted within wetlands, as seen here at the [[Jamaica Bay Wildlife Refuge]] in [[New York City]].]]

===Technical definitions===
A simplified definition of wetland is "an area of land that is usually saturated with water".<ref>{{Cite web |title=Home: Oxford English Dictionary |url=https://www.oed.com/ |access-date=2022-07-08 |website=www.oed.com |language=en}}</ref> More precisely, wetlands are areas where "water covers the [[soil]], or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season".<ref name=":5" /> A patch of land that develops pools of water after a [[rain storm]] would not necessarily be considered a "wetland", even though the land is wet. Wetlands have unique characteristics: they are generally distinguished from other [[water bodies]] or [[landform]]s based on their [[water level]] and on the types of [[plant]]s that live within them. Specifically, wetlands are characterized as having a [[water table]] that stands at or near the [[land surface]] for a long enough period each year to support [[aquatic plants]].<ref>{{cite web |title=Glossary of Terms |url=http://www.cvwd.net/water_glossary.htm |archive-url=https://web.archive.org/web/20120425163056/http://www.cvwd.net/water_glossary.htm |archive-date=April 25, 2012 |access-date=2012-05-23 |publisher=Carpinteria Valley Water District}}</ref><ref>{{cite web |title=Glossary |url=http://mapping2.orr.noaa.gov/portal/calcasieu/calc_html/resources/glossary.html |archive-url=https://web.archive.org/web/20120425163041/http://mapping2.orr.noaa.gov/portal/calcasieu/calc_html/resources/glossary.html |archive-date=2012-04-25 |access-date=2012-05-23 |publisher=Mapping2.orr.noaa.gov}}</ref>

A more concise definition is a community composed of [[hydric soil]] and [[hydrophytes]].<ref name="Keddy2010" />

Wetlands have also been described as [[ecotone]]s, providing a transition between dry land and water bodies.<ref>{{cite web |title=Glossary |url=http://www.alabamapower.com/hydro/glossary.asp |archive-url=https://web.archive.org/web/20120321233304/http://www.alabamapower.com/hydro/glossary.asp |archive-date=2012-03-21 |access-date=2012-05-23 |publisher=Alabama Power}}</ref> Wetlands exist "...at the interface between truly [[terrestrial ecoregion|terrestrial]] ecosystems and [[aquatic habitat|aquatic]] systems, making them inherently different from each other, yet highly dependent on both."<ref name="mitsch2007">{{cite book |last1=Mitsch |first1=William J. |url=https://books.google.com/books?id=1cSKeTCi894C |title=Wetlands |last2=Gosselink |first2=James G. |date=2007-08-24 |publisher=John Wiley & Sons |isbn=978-0-471-69967-5 |edition=4th |location=New York, NY}}</ref>

In environmental decision-making, there are subsets of definitions that are agreed upon to make regulatory and policy decisions.

Under the [[Ramsar Convention|Ramsar international wetland conservation treaty]], wetlands are defined as follows:<ref>{{cite web|title=The Ramsar 40th Anniversary Message for November| publisher = Ramsar| access-date = 2011-10-10 | url = http://www.ramsar.org/cda/en/ramsar-home/main/ramsar/1_4000_0__}}</ref>
* Article 1.1: "...wetlands are areas of marsh, [[fen]], [[peatland]] or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, [[fresh water|fresh]], [[brackish water|brackish]] or [[saline water|salt]], including areas of marine water the depth of which at low tide does not exceed six meters."
* Article 2.1: "[Wetlands] may incorporate [[riparian]] and coastal zones adjacent to the wetlands, and [[island]]s or bodies of marine water deeper than six meters at [[low tide]] lying within the wetlands."
An ecological definition of a wetland is "an ecosystem that arises when inundation by water produces soils dominated by anaerobic and aerobic processes, which, in turn, forces the biota, particularly rooted plants, to adapt to flooding".<ref name="Keddy2010" />

Sometimes a precise legal definition of a wetland is required. The definition used for regulation by the United States government is: 'The term "wetlands" means those areas that are inundated or saturated by surface or ground water at a frequency and duration to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally included swamps, marshes, bogs, and similar areas.'<ref>Environmental Laboratory. (1987). Corps of Engineers wetlands delineation manual. ''Tech. Rep. Y‐87–1''.</ref>

For each of these definitions and others, regardless of the purpose, hydrology is emphasized (shallow waters, water-logged soils). The soil characteristics and the plants and animals controlled by the wetland hydrology are often additional components of the definitions.<ref>{{cite book |last1=Sharitz |first1=Rebecca R. |chapter=Ecology of Freshwater and Estuarine Wetlands: An Introduction |date=2019-12-31 |title=Ecology of Freshwater and Estuarine Wetlands |pages=1–22 |location=Berkeley |publisher=University of California Press |language=en |doi=10.1525/9780520959118-003 |isbn=978-0-520-95911-8 |last2=Batzer |first2=Darold P. |last3=Pennings |first3=Steven C. |s2cid=198427881}}</ref>

=== Types ===
[[File:Sunrise at viru bog.jpg|thumb|upright=1.5|Sunrise at Viru Bog, Estonia]]
{{Main|Classification of wetlands}}
Wetlands can be [[Tide|tidal]] (inundated by tides) or non-tidal.<ref name=":5"/> The water in wetlands is either [[freshwater]], [[brackish water|brackish]], [[Saline water|saline]], or [[alkali]]ne.<ref name="ramsar" /> There are four main kinds of wetlands&nbsp;– [[marsh]], [[swamp]], [[bog]], and [[fen]] (bogs and fens being types of peatlands or [[mire]]s). Some experts also recognize [[wet meadow]]s and [[aquatic ecosystem]]s as additional wetland types.<ref name="Keddy2010" /> Sub-types include [[mangrove swamp|mangrove forests]], [[Carr (landform)|carrs]], [[pocosin]]s, [[floodplain]]s,<ref name="Keddy2010" /> peatlands, [[vernal pool]]s, [[Sink (geography)|sinks]], and many others.<ref name=":0">{{Cite web|url=https://dec.vermont.gov/watershed/wetlands/what/types|title = Wetland Types &#124; Department of Environmental Conservation}}</ref>

The following three groups are used within [[Australia]] to classify wetland by type: Marine and coastal zone wetlands, inland wetlands and human-made wetlands.<ref>{{cite book|date=2001|title=A Directory of Important Wetlands in Australia: Third edition, Chapter 2: Wetland classification system, Criteria for inclusion and Data presentation|url=http://www.environment.gov.au/water/publications/environmental/wetlands/directory.html |access-date=30 March 2021|publisher=Australian Department of the Environment}}</ref> In the US, the best known classifications are the [[Cowardin classification system]]<ref>{{Cite web|title=NPWRC :: Classification of Wetlands and Deepwater Habitats of the United States|url=https://www.fws.gov/wetlands/documents/classwet/index.html|access-date=2018-07-28|website=www.fws.gov|archive-date=2014-01-21|archive-url=https://web.archive.org/web/20140121073314/http://www.fws.gov/wetlands/Documents/classwet/index.html}}</ref> and the hydrogeomorphic (HGM) classification system. The Cowardin system includes five main types of wetlands: [[Marine habitats|marine]] (ocean-associated), [[Estuary|estuarine]] (mixed ocean- and river-associated), [[riverine]] (within river channels), [[lacustrine]] (lake-associated) and [[palustrine]] (inland nontidal habitats).

==== Peatlands ====
[[Mire|Peatlands]] are a unique kind of wetland where lush plant growth and slow decay of dead plants (under anoxic conditions) results in organic peat accumulating; bogs, fens, and mires are different names for peatlands.

=== Wetland names ===
Variations of names for wetland systems:

{{Div col|colwidth=22em}}
* [[Bayou]]
* [[Flooded grasslands and savannas]]
* [[Marsh]]
** [[Brackish marsh]]
** [[Freshwater marsh]]
* [[Mire]]
** [[Fen]]
** [[Bog]]
* [[Riparian zone]]
* [[Swamp]]
** [[Freshwater swamp forest]]
**[[Tidal Freshwater forest]]
** [[Coniferous swamp]]
** [[Peat swamp forest]]
** [[Mangrove swamp]]
* [[Vernal pool]]
{{Div col end}}

Some wetlands have localized names unique to a region such as the prairie potholes of North America's northern plain, [[pocosin]]s, [[Carolina bay]]s and [[baygall]]s<ref name="Watson (2006)">{{cite book |author=Watson, G. E. |title=Big Thicket Plant Ecology: An Introduction |publisher=University of North Texas Press |year=2006 |isbn=978-1574412147 |edition=Third |series=Temple Big Thicket Series #5 |location=Denton, Texas}}</ref><ref name="Texas P&W">{{Cite web |work=Texas Parks and Wildlife. Ecological Mapping systems of Texas |url=https://tpwd.texas.gov/landwater/land/programs/landscape-ecology/ems/emst/woody-wetlands-and-riparian/west-gulf-coastal-plain-seepage-swamp-and-baygall |title=West Gulf Coastal Plain Seepage Swamp and Baygall |archive-url=https://web.archive.org/web/20200710060502/https://tpwd.texas.gov/landwater/land/programs/landscape-ecology/ems/emst/woody-wetlands-and-riparian/west-gulf-coastal-plain-seepage-swamp-and-baygall |archive-date=2020-07-10 |access-date=7 July 2020}}</ref> of the Southeastern US, mallines of Argentina, Mediterranean seasonal ponds of Europe and California, [[Turlough (lake)|turloughs]] of Ireland, [[billabong]]s of Australia, among many others.

=== Locations ===

==== By temperature zone ====
[[File:MiddleSpring.JPG|thumb|Wetlands contrast the hot, arid landscape around Middle Spring, [[Fish Springs National Wildlife Refuge]], [[Utah]].]]
Wetlands are found throughout the world in different climates.<ref name=":5">{{Cite web |last=US EPA |first=OW |date=2015-09-18 |title=What is a Wetland? |url=https://www.epa.gov/wetlands/what-wetland |access-date=2022-07-08 |website=US EPA |language=en}}</ref> Temperatures vary greatly depending on the location of the wetland. Many of the world's wetlands are in the [[temperate zone]]s, midway between the North or South Poles and the equator. In these zones, summers are warm and winters are cold, but temperatures are not extreme. In subtropical zone wetlands, such as along the [[Gulf of Mexico]], average temperatures might be {{convert|11|C|F}}. Wetlands in the [[tropics]] are subjected to much higher temperatures for a large portion of the year. Temperatures for wetlands on the [[Arabian Peninsula]] can exceed {{convert|50|C|F}} and these habitats would therefore be subject to rapid evaporation. In northeastern [[Siberia]], which has a polar climate, wetland temperatures can be as low as {{convert|−50|C|F}}. [[Peatland]]s in arctic and subarctic regions insulate the [[permafrost]], thus delaying or preventing its thawing during summer, as well as inducing its formation.<ref>{{Cite web|url=https://www.ramsar.org/document/peatlands-climate-change-mitigation-biodiversity-conservation|title=Peatlands, climate change mitigation and biodiversity conservation &#124; The Convention on Wetlands, The Convention on Wetlands|website=www.ramsar.org}}</ref>

==== By precipitation amount ====
The amount of precipitation a wetland receives varies widely according to its area. Wetlands in [[Wales]], [[Scotland]], and western [[Ireland]] typically receive about {{convert|1500|mm|in|abbr=on}} per year.{{citation needed|date=December 2022}} In some places in [[Southeast Asia]], where heavy rains occur, they can receive up to {{convert|10000|mm|in|abbr=on}}.{{citation needed|date=December 2022}} In some drier regions, wetlands exist where as little as {{convert|180|mm|in|abbr=on}} precipitation occurs each year.{{citation needed|date=February 2017}}

Temporal variation:<ref>{{Cite web|url=http://www.ramsar.org/cda/en/ramsar-pubs-reports/main/ramsar/1-30-99_4000_0__|title=Ramsar Convention Technical Reports}}</ref>
* [[Perennial]] systems
* [[Seasonal]] systems
* Episodic (periodic or intermittent) systems
* [[Ephemeral]] (short-lived) systems
Surface flow may occur in some segments, with subsurface flow in other segments.