Editing Salt marsh (section)

==Tidal flooding and vegetation zonation==
[[File:Bride-Brook-Salt-Marsh-s.jpg|thumb|300px|right|An Atlantic coastal salt marsh in [[Connecticut]].]]
Coastal salt marshes can be distinguished from terrestrial habitats by the daily [[tide|tidal]] flow that occurs and continuously floods the area.<ref name="adam"/> It is an important process in delivering sediments, nutrients and plant water supply to the marsh.<ref name="bromberg"/> At higher elevations in the [[high marsh|upper marsh]] zone, there is much less tidal inflow, resulting in lower [[salinity]] levels.<ref name="adam"/> [[Soil salinity]] in the [[low marsh|lower marsh]] zone is fairly constant due to everyday annual tidal flow. However, in the upper marsh, variability in salinity is shown as a result of less frequent flooding and climate variations. Rainfall can reduce salinity and [[evapotranspiration]] can increase levels during dry periods.<ref name="adam"/> As a result, there are [[microhabitat]]s populated by different species of [[flora]] and [[fauna]] dependent on their physiological abilities. The flora of a salt marsh is differentiated into levels according to the plants' individual tolerance of salinity and water table levels. Vegetation found at the water must be able to survive high salt concentrations, periodical [[submersion (coastal management)|submersion]], and a certain amount of water movement, while plants further inland in the marsh can sometimes experience dry, low-nutrient conditions. It has been found that the upper marsh zones limit species through competition and the lack of habitat protection, while lower marsh zones are determined through the ability of plants to tolerate physiological stresses such as salinity, water submergence and low oxygen levels.<ref name="bertness">{{Cite journal |last=Bertness |first=Mark D. |last2=Ewanchuk |first2=Patrick J. |last3=Silliman |first3=Brian Reed |date=2002-02-05 |title=Anthropogenic modification of New England salt marsh landscapes |url=https://pnas.org/doi/full/10.1073/pnas.022447299 |journal=Proceedings of the National Academy of Sciences |language=en |volume=99 |issue=3 |pages=1395–1398 |doi=10.1073/pnas.022447299 |issn=0027-8424 |pmc=122201 |pmid=11818525}}</ref><ref name="rand">{{Cite journal |last=Rand |first=Tatyana A. |date=2001-12-24 |title=Seed dispersal, habitat suitability and the distribution of halophytes across a salt marsh tidal gradient |url=https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2745.2000.00484.x |journal=Journal of Ecology |language=en |volume=88 |issue=4 |pages=608–621 |doi=10.1046/j.1365-2745.2000.00484.x |issn=0022-0477}}</ref>
[[File:Saltmarsh-Grass.JPG|thumb|High marsh in the [[Marine Park (Brooklyn park)|Marine Park]] Salt Marsh Nature Center in [[Brooklyn]], New York]]
The [[New England]] salt marsh is subject to strong tidal influences and shows distinct patterns of zonation.<ref name="rand"/> In low marsh areas with high tidal flooding, a monoculture of the smooth [[Spartina|cordgrass]], ''[[Spartina alterniflora]]'' dominate, then heading landwards, zones of the salt hay, ''[[Spartina patens]]'', black rush, ''[[Juncus gerardii]]'' and the shrub ''[[Iva frutescens]]'' are seen respectively.<ref name="bertness"/> These species all have different tolerances that make the different zones along the marsh best suited for each individual.

Plant species diversity is relatively low, since the flora must be tolerant of salt, complete or partial submersion, and anoxic mud substrate. The most common salt marsh plants are [[glasswort]]s (''Salicornia'' spp.) and the cordgrass (''Spartina'' spp.), which have worldwide distribution. They are often the first plants to take hold in a [[mudflat]] and begin its [[ecological succession]] into a salt marsh. Their shoots lift the main flow of the tide above the mud surface while their roots spread into the substrate and stabilize the sticky mud and carry oxygen into it so that other plants can establish themselves as well. Plants such as [[limonium|sea lavenders]] (''Limonium'' spp.), [[plantago|plantains]] (''Plantago'' spp.), and varied [[Cyperaceae|sedges]] and [[Juncaceae|rushes]] grow once the mud has been vegetated by the [[pioneer species]].

Salt marshes are quite photosynthetically active and are extremely productive habitats. They serve as depositories for a large amount of organic matter and are full of decomposition, which feeds a broad food chain of organisms from bacteria to mammals. Many of the halophytic plants such as cordgrass are not grazed at all by higher animals but die off and decompose to become food for micro-organisms, which in turn become food for fish and birds.