Editing Marsh (section)

==Types of marshes==
[[File:Jyväskylä - swamp 2.jpg|thumb|A marsh in [[Jyväskylä]], [[Finland]]|202x202px]]
Marshes differ depending mainly on their location and [[salinity]]. These factors greatly influence the range and scope of animal and plant life that can survive and reproduce in these environments. The three main types of marsh are [[salt marshes]], freshwater [[tidal marsh]]es, and [[freshwater marsh]]es.<ref name="Rafferty" /> These three can be found worldwide, and each contains a different set of organisms.

===Salt marshes===
{{Main|Salt marsh|Brackish marsh|Tidal marsh}}
[[File:Culbin Salt Marsh - geograph.org.uk - 185128.jpg|thumb|upright=0.9|right|A salt marsh in [[Scotland]]]]
Saltwater marshes are found around the world in mid to high [[latitude]]s, wherever there are sections of protected coastline. They are located close enough to the shoreline that the motion of the [[tide]]s affects them, and, sporadically, they are covered with water. They flourish where the rate of sediment buildup is greater than the rate at which the land level is sinking.<ref name="Rafferty" /> Salt marshes are dominated by specially adapted rooted vegetation, primarily salt-tolerant grasses.<ref name="ReferenceA">Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.</ref>

Salt marshes are most commonly found in [[lagoon]]s, [[estuaries]], and on the sheltered side of a shingle or [[Sandspit (landform)|sandspit]]. The currents there carry the fine particles around to the quiet side of the spit, and sediment begins to build up. These locations allow the marshes to absorb the excess nutrients from the water running through them before they reach the oceans and estuaries.<ref name="Rafferty" /> These marshes are slowly declining. Coastal development and [[urban sprawl]] have caused significant loss of these essential habitats.<ref>B.R. Silliman, E.D. Grosholz, and M.D. Bertness (eds.) 2009. Human Impacts on Salt Marshes. A Global Perspective. University of California Press, Berkeley, California.</ref>

===Freshwater tidal marshes===
{{Main|Tidal marsh}}
Although considered a freshwater marsh, the [[ocean tides]] affect this form of marsh. However, without the stresses of salinity at work in its saltwater counterpart, the diversity of the plants and animals that live in and use freshwater tidal marshes is much higher than in salt marshes. The most severe threats to this form of marsh are the increasing size and pollution of the cities surrounding them.<ref name="Rafferty" />

===Freshwater marshes===
{{Main|Freshwater marsh|Wet meadow|Vernal pool|Dry lake}}
[[File:MeadowInBigBear.JPG|thumb|upright=0.9|A [[wet meadow]] adjacent to [[Big Bear Lake]], [[San Bernardino Mountains]], California]]

Ranging greatly in size and geographic location, freshwater marshes make up North America's most common form of wetland.  They are also the most diverse of the three types of marsh. Some examples of freshwater marsh types in North America are:

====Wet meadows====
[[Wet meadow|Wet meadows]] occur in shallow lake basins, low-lying depressions, and the land between shallow marshes and upland areas. They also happen on the edges of large lakes and rivers. Wet meadows often have very high plant diversity and high densities of buried seeds.<ref name="ReferenceA" /><ref>Keddy, P.A. and A. A. Reznicek.  1986.  Great Lakes vegetation dynamics:  the role of fluctuating water levels and buried seeds.  Journal of Great Lakes Research 12: 25–36.</ref> They are regularly flooded but are often dry in the summer.

====Vernal pools====
[[Vernal pool|Vernal pools]] are a type of marsh found only seasonally in shallow depressions in the land. They can be covered in shallow water, but in the summer and fall, they can be completely dry. In western North America, vernal pools tend to form in open grasslands,<ref>Bauder, E. T. 1989. Drought stress and competition effects on the local distribution of ''Pogogyne abramsii''. Ecology 70: 1083–9.</ref> whereas in the east, they often occur in forested landscapes.<ref>Calhoun, A.J.K. and P.G. deMaynadier. 2008. Science and the Conservation of Vernal Pools in Northeastern North America. CRC Press, Boca Raton, Florida.</ref> Further south, vernal pools form in pine savannas and [[flatwoods]]. Many amphibian species depend upon vernal pools for spring breeding; these ponds provide a habitat free from fish, which eat the eggs and young of amphibians.<ref name="ReferenceA" /> An example is the endangered [[gopher frog]].<ref>Richter, S. C. and Seigel, R. A. 2002. Annual variation in the population ecology of the endangered gopher frog, Rana sevosa Goin and Netting. Copeia, 2002, 962–72.</ref> Similar temporary ponds occur in other world ecosystems, where they may have local names.  However, vernal pool can be applied to all such temporary pool ecosystems.<ref name="ReferenceA" />

====Playa lakes====
[[Playa lake]]s are a form of shallow freshwater marsh in the southern high plains of the United States.<ref>Smith, L. M. 2003. Playas of the Great Plains. Austin, TX: University of Texas Press.</ref> Like vernal pools, they are only present at certain times of the year and generally have a circular shape.<ref>{{cite web|last=United States Environmental Protection Agency|title=Playa Lakes|url=http://water.epa.gov/type/wetlands/playa.cfm|access-date=5 February 2012|url-status=live|archive-url=https://web.archive.org/web/20120204144636/http://water.epa.gov/type/wetlands/playa.cfm|archive-date=4 February 2012}}</ref> As the playa dries during the summer, conspicuous plant zonation develops along the shoreline.<ref>Bolen, E. G., Smith, L. M., and Schramm, H. L., Jr. 1989. Playa lakes: prairie wetlands of the southern High Plains. BioScience 39: 615–23.</ref>

===Prairie potholes===
[[File:VernalPool.jpg|thumb|201x201px|[[Vernal pool]]s are ponded only during the wetter part of the year.]]
[[File:Prairie Pothole Wetlands.jpg|thumb|upright=0.9|right|Aerial view of prairie potholes]]
Prairie potholes are found in northern North America, such as the [[Prairie Pothole Region]]. Glaciers once covered these landscapes, and as a result, shallow depressions were formed in great numbers. These depressions fill with water in the spring. They provide important breeding habitats for many species of waterfowl. Some pools only occur seasonally, while others retain enough water to be present all year.<ref>van der Valk, A. G. 1989. Northern Prairie Wetlands. Ames, IA: Iowa State University Press.</ref>

=== Riverine wetlands ===
Many kinds of marsh occur along the fringes of large rivers.  The different types are produced by factors such as water level, nutrients, [[ice scour]], and waves.<ref>Day, R., P.A. Keddy, J. McNeill and T. Carleton. 1988. Fertility and disturbance gradients: a summary model for riverine marsh vegetation.  Ecology 69: 1044–1054</ref>

===Embanked marshlands===
{{Main|Tidal marsh}}
Large tracts of tidal marsh have been embanked and artificially drained. They are usually known by the Dutch name of [[polder]]s. In Northern Germany and Scandinavia they are called ''[[:de:Marschland|Marschland]]'', ''Marsch'' or ''marsk''; in France ''marais maritime''. In the Netherlands and Belgium, they are designated as [[marine clay]] districts. In [[East Anglia]], a region in the [[East of England]], the embanked marshes are also known as [[The Fens|Fens]].