Wetland

Wetlands come in different sizes and types. From top left: Upland vs. wetland vs. lacustrine zones; freshwater swamp forest in Bangladesh; peat bogs are freshwater wetlands that develop in areas with standing water and low soil fertility; a freshwater cattail (Typha) marsh that develops with standing water and high soil fertility.

A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently for years or decades or seasonally for a shorter periods. Flooding results in oxygen-poor (anoxic) processes taking place, especially in the soils.^[1] Wetlands are different from other land forms or water bodies due to their aquatic plants adapted to oxygen-poor waterlogged soils.^[2] Wetlands are considered among the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal species. Methods exist for assessing wetland functions and wetland ecological health. These methods have contributed to wetland conservation by raising public awareness of the functions that wetlands can provide.^[3] Constructed wetlands are a type of wetland that can treat wastewater and stormwater runoff. They may also play a role in water-sensitive urban design. Environmental degradation threatens wetlands more than any other ecosystem on Earth, according to the Millennium Ecosystem Assessment from 2005.^[4]

Wetlands exist on every continent.^[5] The water in wetlands is either freshwater, brackish, or saltwater.^[2] The main wetland types are classified based on the dominant plants and the source of the water. For example, marshes are wetlands dominated by emergent vegetation such as reeds, cattails and sedges. Swamps are dominated by woody vegetation such as trees and shrubs (although reed swamps in Europe are dominated by reeds, not trees).

Examples of wetlands classified by the sources of water include tidal wetlands (where the water source is ocean tides), estuaries (water source is mixed tidal and river waters), floodplains (water source is excess water from overflowed rivers or lakes), and bogs and vernal ponds (water source is rainfall or meltwater).^[1]^[6] Some wetlands have multiple types of plants and are fed by multiple sources of water, making them difficult to classify. The world's largest wetlands include the Amazon River basin, the West Siberian Plain,^[7] the Pantanal in South America,^[8] and the Sundarbans in the Ganges-Brahmaputra delta.^[9]

Wetlands contribute many functions that benefit people. These are called ecosystem services and include for example water purification, stabilization of shorelines and storm protection, and flood control. In addition, wetlands also process and break down carbon (in processes called carbon fixation, decomposition and carbon sequestration), and other nutrients and pollutants. Wetlands are reservoirs of biodiversity and support many plants and animals.

Wetlands can be a sink or a source of carbon, depending on the specific wetland. If they function as a carbon sink, they can help with climate change mitigation. However, wetlands can also be a significant source of methane emissions, and some are also emitters of nitrous oxide.^[10]^[11]

^ ^a ^b Keddy, P.A. (2010). Wetland ecology: principles and conservation (2nd ed.). New York: Cambridge University Press. ISBN 978-0521519403. Archived from the original on 2023-03-17. Retrieved 2020-06-03.
^ ^a ^b "Official page of the Ramsar Convention". Retrieved 2011-09-25.
^ Dorney, J.; Savage, R.; Adamus, P.; Tiner, R., eds. (2018). Wetland and Stream Rapid Assessments: Development, Validation, and Application. London; San Diego, CA: Academic Press. ISBN 978-0-12-805091-0. OCLC 1017607532.
^ Davidson, N.C.; D'Cruz, R. & Finlayson, C.M. (2005). Ecosystems and Human Well-being: Wetlands and Water Synthesis: a report of the Millennium Ecosystem Assessment (PDF). Washington, DC: World Resources Institute. ISBN 978-1-56973-597-8.
^ Davidson, N.C. (2014). "How much wetland has the world lost? Long-term and recent trends in global wetland area". Marine and Freshwater Research. 65 (10): 934–941. doi:10.1071/MF14173. S2CID 85617334.
^ "US EPA". 2015. Retrieved 2011-09-25.
^ Fraser, L.; Keddy, P.A., eds. (2005). The World's Largest Wetlands: Their Ecology and Conservation. Cambridge, UK: Cambridge University Press. ISBN 978-0521834049.
^ "WWF Pantanal Programme". Retrieved 2011-09-25.
^ Giri, C.; Pengra, B.; Zhu, Z.; Singh, A.; Tieszen, L.L. (2007). "Monitoring mangrove forest dynamics of the Sundarbans in Bangladesh and India using multi-temporal satellite data from 1973 to 2000". Estuarine, Coastal and Shelf Science. 73 (1–2): 91–100. Bibcode:2007ECSS...73...91G. doi:10.1016/j.ecss.2006.12.019.
^ Bange, H. W. (2006). "Nitrous oxide and methane in European coastal waters". Estuarine, Coastal and Shelf Science. 70 (3): 361–374. Bibcode:2006ECSS...70..361B. doi:10.1016/j.ecss.2006.05.042.
^ Thompson, A. J.; Giannopoulos, G.; Pretty, J.; Baggs, E. M.; Richardson, D. J. (2012). "Biological sources and sinks of nitrous oxide and strategies to mitigate emissions". Philosophical Transactions of the Royal Society B. 367 (1593): 1157–1168. doi:10.1098/rstb.2011.0415. PMC 3306631. PMID 22451101.

[Keddy2010-1] Keddy, P.A. (2010). Wetland ecology: principles and conservation (2nd ed.). New York: Cambridge University Press. ISBN 978-0521519403. Archived from the original on 2023-03-17. Retrieved 2020-06-03.

[ramsar-2] "Official page of the Ramsar Convention". Retrieved 2011-09-25.

[ACADEMIC_PRESS-3] Dorney, J.; Savage, R.; Adamus, P.; Tiner, R., eds. (2018). Wetland and Stream Rapid Assessments: Development, Validation, and Application. London; San Diego, CA: Academic Press. ISBN 978-0-12-805091-0. OCLC 1017607532.

[4] Davidson, N.C.; D'Cruz, R. & Finlayson, C.M. (2005). Ecosystems and Human Well-being: Wetlands and Water Synthesis: a report of the Millennium Ecosystem Assessment (PDF). Washington, DC: World Resources Institute. ISBN 978-1-56973-597-8.

[Davidson2014-5] Davidson, N.C. (2014). "How much wetland has the world lost? Long-term and recent trends in global wetland area". Marine and Freshwater Research. 65 (10): 934–941. doi:10.1071/MF14173. S2CID 85617334.

[water-6] "US EPA". 2015. Retrieved 2011-09-25.

[FraserKeddy-7] Fraser, L.; Keddy, P.A., eds. (2005). The World's Largest Wetlands: Their Ecology and Conservation. Cambridge, UK: Cambridge University Press. ISBN 978-0521834049.

[:1-8] "WWF Pantanal Programme". Retrieved 2011-09-25.

[:2-9] Giri, C.; Pengra, B.; Zhu, Z.; Singh, A.; Tieszen, L.L. (2007). "Monitoring mangrove forest dynamics of the Sundarbans in Bangladesh and India using multi-temporal satellite data from 1973 to 2000". Estuarine, Coastal and Shelf Science. 73 (1–2): 91–100. Bibcode:2007ECSS...73...91G. doi:10.1016/j.ecss.2006.12.019.

[:4-10] Bange, H. W. (2006). "Nitrous oxide and methane in European coastal waters". Estuarine, Coastal and Shelf Science. 70 (3): 361–374. Bibcode:2006ECSS...70..361B. doi:10.1016/j.ecss.2006.05.042.

[:3-11] Thompson, A. J.; Giannopoulos, G.; Pretty, J.; Baggs, E. M.; Richardson, D. J. (2012). "Biological sources and sinks of nitrous oxide and strategies to mitigate emissions". Philosophical Transactions of the Royal Society B. 367 (1593): 1157–1168. doi:10.1098/rstb.2011.0415. PMC 3306631. PMID 22451101.

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