Editing Wetland (section)

===Hydrology===
[[File:Wetlands Cape May New Jersey.jpg|thumb|300px|The wetlands of [[Cape May]], [[New Jersey]], in the [[United States]] comprise an extensive hydrological network that makes them an [[ornithology|ornithologically]] important location to study the many birds which use the preserve as a place to [[nest]].]]
[[File:Mallows Bay Park wetlands.PNG|300px|thumb|A wetland in the [[Chesapeake Bay]] [[drainage basin]] in Mallows Bay Park in [[Charles County, Maryland|Charles County]], [[Maryland]], in the United States.]]
The most important factor producing wetlands is hydrology, or [[flooding]]. The duration of flooding or prolonged soil saturation by [[groundwater]] determines whether the resulting wetland has aquatic, [[marsh]] or [[swamp]] [[vegetation]]. Other important factors include soil fertility, natural disturbance, competition, [[herbivory]], burial, and salinity.<ref name="Keddy2010" /> When [[peat]] from dead plants accumulates, [[bog]]s and [[fen]]s develop.

Wetland hydrology is associated with the spatial and temporal dispersion, flow, and physio-chemical attributes of surface and ground waters. Sources of hydrological flows into wetlands are predominantly [[precipitation]], surface water (saltwater or freshwater), and groundwater. Water flows out of wetlands by [[evapotranspiration]], surface flows and [[tide]]s, and subsurface water outflow. [[Hydrodynamics]] (the movement of water through and from a wetland) affects hydro-periods (temporal fluctuations in water levels) by controlling the water balance and water storage within a wetland.<ref>{{cite book|last1=Richardson|first1=J. L.|last2=Arndt|first2=J. L.|last3=Montgomery|first3=J. A.|date=2001|contribution=Hydrology of wetland and related soils|editor1-first=J. L.|editor1-last=Richardson|editor2-first=M. J.|editor2-last=Vepraskas|title=Wetland Soils|publisher=Lewis Publishers|location=Boca Raton, FL}}</ref>

Landscape characteristics control wetland hydrology and water chemistry. The [[oxygen|O<sub>2</sub>]] and [[carbon dioxide|CO<sub>2</sub>]] concentrations of water depend upon [[temperature]], [[atmospheric pressure]] and mixing with the air (from winds or water flows). Water chemistry within wetlands is determined by the [[pH]], [[salinity]], nutrients, [[Electrical conductivity|conductivity]], soil composition, [[Water hardness|hardness]], and the sources of water. Water chemistry varies across landscapes and climatic regions. Wetlands are generally [[minerotrophic]] (waters contain dissolved materials from soils) with the exception of [[ombrotrophic]] bogs that are fed only by water from precipitation.

Because bogs receive most of their water from precipitation and humidity from the [[atmosphere]], their water usually has low [[mineral]] ionic composition. In contrast, wetlands fed by groundwater or tides have a higher [[concentration]] of dissolved nutrients and minerals.

Fen peatlands receive water both from precipitation and ground water in varying amounts so their water chemistry ranges from acidic with low levels of dissolved minerals to alkaline with high accumulation of [[calcium]] and [[magnesium]].<ref>{{cite journal|last1=Vitt|first1=D. H.|last2=Chee|first2=W|date=1990|title=The relationships of vegetation to surface water chemistry and peat chemistry in fens of Alberta, Canada|journal=Plant Ecology|volume=89|issue=2|pages=87–106|doi=10.1007/bf00032163|s2cid=25071105}}</ref>