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[[File:Mangrove trees in Everglades.JPG|thumb|250px|right|[[Florida]]'s [[Everglades]], the largest wetland system in the United States.<ref>http://www.ens-newswire.com/ens/apr2002/2002-04-15-06.asp</ref>]] |
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{{biome}} |
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A '''wetland''' is an area of land whose [[soil]] is [[Aquifer|saturated]] with [[moisture]] either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water.<ref>{{cite web | title = National Geographic's Strange Days on Planet Earth: Glossary | publisher = Public Broadcasting Service | accessdate = 2009-10-02 | url = http://www.pbs.org/strangedays/glossary/W.html}}</ref> Wetlands include [[swamp]]s, [[marsh]]es, and [[bog]]s, among others. The [[water]] found in wetlands can be [[Seawater|saltwater]], [[freshwater]], or [[brackish]]. The world's largest wetland is the [[Pantanal]] which straddles [[Brazil]], [[Bolivia]] and [[Paraguay]] in [[South America]]. |
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Wetlands are considered the most [[biologically diverse]] of all [[ecosystems]]. Plant life found in wetlands includes [[mangrove]], [[Nymphaeaceae|water lilies]], [[cattails]], [[sedges]], [[tamarack]], [[black spruce]], [[cypress]], [[gum tree|gum]], and many others. Animal life includes many different [[amphibians]], [[reptiles]], [[birds]], [[insects]], and [[mammals]].<ref name="class"/> |
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In many locations, such as the [[United Kingdom]], [[Iraq]], [[South Africa]] and the [[United States]], wetlands are the subject of [[Conservation movement|conservation]] efforts and [[Biodiversity Action Plan]]s. |
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Wetlands also serve as natural wastewater purification systems—e.g., in Calcutta, India<ref>[http://ecotippingpoints.org/our-stories/indepth/india-calcutta-wetland-wastewater-agriculture-fishpond East Calcutta Wetlands: Wastewater, Fishponds, and Agriculture]</ref> and Arcata, California.<ref>[http://ecotippingpoints.org/our-stories/indepth/usa-california-arcata-constructed-wetland-wastewater Arcata, California Constructed Wetland: A Cost-Effective Alternative for Wastewater Treatment]</ref> |
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The study of wetlands has recently been termed '''paludology''' in some publications.<ref>http://psjc.icm.edu.pl/psjc/cgi-bin/getdoc.cgi?AAAA015683</ref> |
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== Technical definitions == |
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Wetlands have been categorized both as [[biome]]s and [[ecosystem]]s.<ref name="class" /> A patch of land that develops pools of water after a rain storm would not be considered a "wetland" though the land is wet. Wetlands have unique characteristics: they are generally distinguished from other [[water bodies]] or [[landforms]] based on their [[water level]] and on the types of [[plant]]s that thrive within them. Specifically, wetlands are characterized as having a [[water table]] that stands at or near the [[land surface]] for a long enough [[season]] each year to support [[aquatic plants]].<ref name="class">http://www.thewildclassroom.com/biomes/wetlands.html</ref><ref>http://www.cvwd.net/water_glossary.htm</ref><ref>http://mapping2.orr.noaa.gov/portal/calcasieu/calc_html/resources/glossary.html</ref> Put simply, wetlands are lands made up of [[hydric soil]]. |
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Wetlands have also been described as [[ecotone]]s, providing a transition between [[Landform|dry land]] and [[water bodies]].<ref>http://www.alabamapower.com/hydro/glossary.asp</ref> Mitsch and Gosselink write that 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 |
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|last=Mitsch |
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|first=William J. |
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|coauthors=James G. Gosselink |
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|title=Wetlands |
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|edition=4th |
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|date=2007-08-24 |
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|publisher=John Wiley & Sons |
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|location=New York |
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|isbn=978-0471699675}}</ref> |
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=== Ramsar Convention definition === |
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Under the [[Ramsar Convention|Ramsar]] international wetland conservation treaty, wetlands are defined as follows: |
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*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, [[brackish]] or [[Seawater|salt]], including areas of marine water the depth of which at low tide does not exceed six metres." |
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*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 metres at [[low tide]] lying within the wetlands". |
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=== Regional definitions === |
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In the United States, wetlands are defined as "those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas"<ref>EPA Regulations listed at 40 CFR 230.3(t)</ref>. Some states, such as [[Massachusetts]] and [[New York]], have separate definitions that may differ from United States federal laws. |
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== Wetlands and climate change == |
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Wetlands perform two important functions in relation to climate change. They have mitigation effects through their ability to [[Carbon sink|sink carbon]], and adaptation effects through their ability to store and regulate water. |
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=== Mitigation === |
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Peatswamp forests and soils are being drained, burnt, mined, and overgrazed contributing severely to climate change. As Peatlands form only 3% of all the world’s land area, their degradation equal 7% of all fossil fuel carbon dioxide (CO<sub>2</sub>) emissions. As a result of peat drainage, the organic carbon that was built up over thousands of years and is normally under water, is suddenly exposed to the air. It decomposes and turns into carbon dioxide (CO<sub>2</sub>), which is released into the atmosphere. Peat fires cause the same process and in addition create enormous clouds of smoke that cross international borders, such as happen every year in Southeast Asia. |
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Through the building of dams, Wetlands International is halting the drainage of peatlands in Southeast Asia, thereby avoiding enormous CO<sub>2</sub> emissions. Reforestation with native tree species as well as setting up community fire brigades are also part of an integral, very cost effective approach shown in Central Kalimantan and Sumatra, Indonesia. (from: www.wetlands.org) |
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=== Adaptation === |
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Mangroves, floodplains, highland and other wetlands can reduce the impacts of increased precipitation, storms, glacier melting and even sealevel rise. The water regulating and storage functions of these wetlands are crucial in adapting to a changing climate. Therefore, in order to protect people living close or even far downstream from wetlands and their source of livelihoods, we must conserve and restore wetlands. In this way, they can continue to play their critical role. (from www.wetlands.org) |
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== Conservation == |
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Wetlands have historically been the victim of large-scale draining efforts for [[real estate development]], or [[flooding]] for use as recreational [[lakes]]. By 1993 half the world's wetlands had been drained.<ref>{{cite journal|title= unknown title|date=1993-10-09|journal=[[New Scientist]]|issue=1894|pages=46}}</ref> Since the 1970s, more focus has been put on preserving wetlands for their natural function — sometimes also at great expense. Wetlands provide a valuable flood control function. Wetlands are very effective at filtering and cleaning [[water pollution]] <ref>[http://www.wild.org/blog/letting-nature-do-the-job Letting Nature Do the Job]</ref>, (often from [[agricultural runoff]] from the farms that replaced the wetlands in the first place). To replace these wetland [[ecosystem services]] enormous amounts of money have been spent on [[water purification]] plants and remediation measures, constructing dams, leves and other artificial flood controls. |
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=== Ramsar Convention === |
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{{Main|Ramsar Convention}} |
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''The Convention on Wetlands of International Importance, especially as Waterfowl Habitat'', or Ramsar Convention, is an international [[treaty]] designed to address global concerns regarding wetland loss and degradation. The primary purposes of the treaty are to list wetlands of international importance and to promote their wise use, with the ultimate goal of preserving the world's wetlands. Methods include restricting access to the majority portion of wetland areas, as well as educating the public to combat the misconception that wetlands are wastelands. |
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===Conservation by country=== |
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====New Zealand==== |
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{{Main|Wetlands of New Zealand}} |
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Over 90% of the wetlands in [[New Zealand]] have been drained since [[Europe]]an settlement, predominantly to create farmland. Wetlands now have a degree of protection under the [[Resource Management Act]]. |
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====South Africa==== |
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The [[South African Department of Environmental Affairs and Tourism]] in conjunction with the departments of Water Affairs and Forestry, and of Agriculture, supports the conservation and rehabilitation of wetlands through the Working for Wetlands program.<ref>http://wetlands.sanbi.org/ Working for Wetlands</ref> The aim of this program is to encourage the protection, rehabilitation and sustainable use of South African wetlands through co-operative governance and partnerships. The program is also a [[poverty relief]] effort, providing employment in wetland maintenance. |
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====Sweden==== |
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The Swedish national wetland inventory (VMI) is one of the world's most extensive systematic inventories of nature types that has ever been done. VMI has surveyed the wetlands of [[Sweden]] below the alpine region during a 25-year period.<ref>{{cite web | url=http://www.naturvardsverket.se/Documents/publikationer/978-91-620-5925-5.pdf | title=Swedish national wetland inventory - The result of 25 years of inventories | publisher=''Swedish Environmental Protection Agency'' | accessdate=23 August 2010}}</ref> In total 35 000 objects (sites) are included in VMI, corresponding to an area of 4.3 million hectares, or 10% of the land area of Sweden. The aim of the survey has been to increase the general knowledge of wetlands in Sweden, as a basis for environmental monitoring and natural resources planning. By investigating the impact of human activities on wetlands and identifying the most valuable wetlands, their values can be preserved for future generations. The results from the inventory were also meant to function as background data for the authorities' decisions concerning e.g. drainage permits. |
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====United States==== |
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{{Main|Wetlands of the United States|Clean Water Act}} |
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The USA came to understand how biologically productive wetlands are, so the USA passed laws limiting wetlands destruction, and created requirements that if a wetland had to be drained, developers at least had to offset the loss by creating artificial wetlands. One example is the project by the [[U.S. Army Corps of Engineers]] to control flooding and enhance development by taming the [[Everglades]], a project which has now been reversed to restore much of the wetlands as a natural [[habitat]] for plant and animal life, as well as a method of [[flood control]]. Another project in the works to restore the Everglades is the [http://www.evergladesfoundation.org/pages/us-sugar U.S Sugar Corp Land Transaction]. The project entails the acquisition of U.S. Sugar Corp. land, which would allow for water delivery, water treatment and water storage of sufficient quantity and quality to mimic the Everglades' natural system. The [[Everglades Foundation]], a foundation whose mission is to protect and restore one of the world’s unique natural ecosystems, and other environment-based organizations support the state of Florida acting to secure U.S. Sugar Corp. land. <ref>Everglades Foundation. [http://www.evergladesfoundation.org/pages/us-sugar US Sugar.] Retrieved 2010-07-23.</ref> |
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===Mapping=== |
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{{Very long|section|date=September 2010}} |
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{{Wikify|section|date=September 2010}} |
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There are many remote sensing methods that can be used to map wetlands. Remote-sensing technology permits the acquisition of timely digital data on a repetitive basis. This repeat coverage allows wetlands, as well as the adjacent land-cover and land-use types, to be monitored seasonally and/or annually. Using digital data provides a standardized data-collection procedure and an opportunity for data integration within a geographic information system. Traditionally, Landsat 5 Thematic Mapper (TM), Landsat 7 |
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Enhanced Thematic Mapper Plus (ETM + ), and the SPOT 4 and 5 satellite systems have been used for this purpose. More recently, however, multispectral IKONOS and QuickBird data, with spatial resolutions of 4m by 4m and 2.44m by 2.44 m, respectively, have been shown to be excellent sources of data when mapping and monitoring smaller wetland habitats and vegetation communities. |
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A wide range of remote sensing studies has been undertaken in a variety of wetland environments. Remote sensing technology has permitted the acquisition of timely digital data on a repetitive basis. For example, the wetlands and vegetation within Detroit Lakes Wetland management District has been assessed using remote sensing. In mapping and monitoring large geographic areas, analysis of satellite images is less costly and time-consuming compared to visual interpretation of aerial photographs. Aerial photographs also require experienced interpreters to extract information based on structure and texture while remote sensing only requires the analysis of the spectral characteristics of data. |
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However, there are a number of limitations associated with image acquisition. Analysis of wetlands has proved difficult because to obtain the data, it has to be linked with practical purposes such as the analysis of land cover or land use. Wetlands, in particular are difficult to monitor, are often difficult to access, especially their inner reaches, and are sometimes home to dangerous wildlife and endemic diseases. Developing a global inventory of wetlands has proven to be a large and difficult undertaking. Current efforts are based on available data, but both classification and spatial resolution may be inadequate for regional or site-specific management decision-making. It is difficult to identify small, long, and narrow wetlands within the landscape. Current efforts using today’s remote sensing satellites may not have sufficient spatial and spectral resolution to monitor wetland conditions, although multispectral IKONOS and QuickBird data may offer improved spatial resolutions of 4m or higher. Majority of the pixels are just mixtures of several plant species or vegetation types and are difficult to isolate. Improved remote sensing information, coupled with good knowledge domain on wetlands will facilitate expanded efforts in wetland monitoring and mapping. This will also be extremely important because we expect to see major shifts in species composition due to both anthropogenic (land use) and natural changes in the environment caused by climate change. Methods to focus the classification on specific classes of interest so that identification can be done with very high accuracies should be looked into. The issue of the cost and expertise involved in remote sensing technology is still a factor hindering further advancements in image acquisition and data processing. Future improvements in wetland vegetation mapping could include the use of more recent and better geospatial data. |
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== Climate == |
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===Temperature=== |
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[[Image:MiddleSpring.JPG|thumb|Wetlands contrast the hot, arid landscape around Middle Spring, [[Fish Springs National Wildlife Refuge]], [[Utah]].]] |
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Temperatures vary greatly depending on the location of the wetland. Many of the world's wetlands are in temperate zones (midway between the North and South Poles and the equator). In these zones, summers are warm and winters are cold, but temperatures are not extreme. However, wetlands found in the tropic zone, which is around the equator, are always warm. Temperatures in wetlands on the Arabian Peninsula, for example, can reach 50 °C (122 °F). In northeastern Siberia, which has a polar climate, wetland temperatures can be as cold as −50 °C (−58 °F). |
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===Rainfall=== |
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The amount of rainfall a wetland receives depends upon its location. Wetlands in Wales, Scotland, and Western Ireland receive about 150 cm (59 in) per year. Those in Southeast Asia, where heavy rains occur, can receive up to 1000 cm (200 in). In the northern areas of North America, wetlands exist where as little as 18 cm (6 in) of rain fall each year. |
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== List of wetland types == |
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{{Multicol}} |
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*[[Swamp]] |
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**[[Freshwater swamp forest]] |
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**[[Coniferous swamp]] |
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*[[Marsh]] |
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**[[Salt marsh]] |
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*[[Bog]] |
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**[[Peat swamp forest]] |
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{{Multicol-break}} |
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*Slough |
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*[[Flooded grasslands and savannas]] |
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*[[Constructed wetland]] |
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*[[Riparian zone]] |
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{{Multicol-end}} |
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==See also== |
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{{Portal box|Environment|Ecology|Earth sciences|Sustainable development}} |
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*[[Converted wetland]] |
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*[[Saline marshlands]] |
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*[[Society of Wetland Scientists]] (SWS) |
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*[[Wetland conservation]] |
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== References == |
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{{Reflist|2}} |
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== Further reading == |
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*Mitsch, W.J., J.G. Gosselink, C.J. Anderson, and L. Zhang. (2009) "[http://www.wiley.com/WileyCDA/WileyTitle/productCd-047028630X.html Wetland Ecosystems]". John Wiley & Sons, Inc., New York, 295 pp. |
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*Ghabo, A. A. (2007) [http://www.terranuova.info/file_download/51 Wetlands Characterization; Use by Local Communities and Role in Supporting Biodiversity in the Semiarid Ijara District, Kenya]. Terra Nuova East Africa. Wetlands in drylands. |
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*[http://www.cpe.rutgers.edu/brochures/pdfs/1987-Army-Corps-Wetlands-Delineation-Manual.pdf 1987 U.S. Army Corps of Engineers Wetland delineation manual] |
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*Dugan, Patrick (editor) (1993) ''Wetlands in Danger'', World Conservation Atlas Series |
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*Brinson, M. (1993) [http://el.erdc.usace.army.mil/wetlands/pdfs/wrpde4.pdf A Hydrogeomorphic Classification of Wetlands] |
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*Fredrikson, Leigh H. (1983) [http://naldr.nal.usda.gov/NALWeb/Agricola_Link.asp?Accession=IND84105117 "Wetlands: A Vanishing Resource"] Yearbook of Agriculture |
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*W.H. MacKenzie and J.R. Moran (2004) "Wetlands of British Columbia: A Guide to Identification. Ministry of Forests, Land Management Handbook 52. [http://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh52.pdf] |
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== External links == |
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{{Commons category|Wetlands}} |
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* [http://www.wetlands.org Wetlands International - A non-profit global organisation to sustain and restore wetlands, their resources and biodiversity for future generations] |
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* [http://www.fws.gov/wetlands/ US Fish & Wildlife Service: National Wetlands Inventory] |
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* [http://www.articlemyriad.com/37.htm Wetlands: The Ecological Effect of Loss (Research article)] |
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* {{fr}}[http://www.forum-marais-atl.com/ Pôle-relais zones humides littorales de la façade atlantique, Manche et Mer du Nord] |
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* [http://www.esterosdelibera.com/ Marshlands of Iberá] (in English and Spanish) |
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* [http://www.nal.usda.gov/wqic/wetl.shtml Wetlands] Water Quality Information Center, U.S. Department of Agriculture |
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* [http://www.centrostudinatura.it/ Centro Studi Naturalistici] |
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* [http://blog.sprlaw.com/category/wetlands/ Wetlands legal updates] |
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* [http://www.wwf.org.hk/eng/maipo/?source=fp-topmenu Wetland of Hong Kong] |
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* [http://www.forum-marais-atl.com/ Forum des Marais Atlantiques - Pôle-relais zones humides littorales de la façade atlantique, Manche et Mer du Nord] |
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{{aquatic ecosystem topics}} |
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[[Category:Wetlands| ]] |
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[[ar:منطقة رطبة]] |
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[[ca:Zona humida]] |
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[[cs:Mokřad]] |
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[[da:Vådområde]] |
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[[de:Feuchtgebiet]] |
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[[et:Märgala]] |
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[[es:Humedal]] |
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[[eo:Malsekejo]] |
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[[fa:تالاب]] |
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[[fr:Zone humide]] |
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[[ko:습지]] |
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[[hr:Vlažno područje]] |
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[[id:Lahan basah]] |
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[[it:Zona umida]] |
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[[ka:ვეთლენდი]] |
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[[lv:Mitrājs]] |
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[[lt:Šlapynė]] |
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[[hu:Wetland]] |
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[[nl:Drasland]] |
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[[ne:सिमसार]] |
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[[ja:湿地]] |
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[[no:Våtmark]] |
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[[pl:Mokradło]] |
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[[pt:Zona úmida]] |
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[[ru:Водно-болотные угодья]] |
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[[sk:Mokraď (územie)]] |
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[[sl:Mokrišče]] |
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[[fi:Kosteikko]] |
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[[sv:Våtmark]] |
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[[th:พื้นที่ชุ่มน้ำ]] |
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[[vi:Đất ngập nước]] |
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[[zh-yue:濕地]] |
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[[zh:湿地]] |
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Revision as of 14:31, 9 September 2010
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