A swamp is a forested wetland.[1] Swamps are considered to be transition zones because both land and water play a role in creating this environment.[2] Swamps vary in size and are located all around the world. The water of a swamp may be fresh water, brackish water, or seawater. Freshwater swamps form along large rivers or lakes where they are critically dependent upon rainwater and seasonal flooding to maintain natural water level fluctuations.[2][3]Saltwater swamps are found along tropical and subtropical coastlines.[4] Some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation[5] or soil saturation. The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps. In the boreal regions of Canada, the word swamp is colloquially used for what is more formally termed a bog, fen, or muskeg. Some of the world's largest swamps are found along major rivers such as the Amazon, the Mississippi, and the Congo.[6]
Differences between marshes and swamps
Swamps and marshes are specific types of wetlands that form along waterbodies containing rich, hydric soils.[7] Marshes are wetlands, continually or frequently flooded by nearby running bodies of water, that are dominated by emergent soft-stem vegetation and herbaceous plants. Swamps are wetlands consisting of saturated soils or standing water and are dominated by water-tolerant woody vegetation such as shrubs, bushes, and trees.[8][4]
Hydrology
Swamps are characterized by their saturated soils and slow-moving waters.[8] The water that accumulates in swamps comes from a variety of sources including precipitation, groundwater, tides and/or freshwater flooding.[4] These hydrologic pathways all contribute to how energy and nutrients flow in and out of the ecosystem. As water flows through the swamp, nutrients, sediment and pollutants are naturally filtered out. Chemicals like phosphorus and nitrogen that end up in waterways get absorbed and used by the aquatic plants within the swamp, purifying the water. Any remaining or excess chemicals present will accumulate at the bottom of the swamp, being removed from the water and buried within the sediment.[2] The biogeochemical environment of a swamp is dependent on its hydrology, affecting the levels and availability of resources like oxygen, nutrients, water pH and toxicity, which will influence the whole ecosystem.[4]
Values and ecosystem services
Swamps and other wetlands have traditionally held a very low property value compared to fields, prairies, or woodlands. They have a reputation for being unproductive land that cannot easily be utilized for human activities, other than hunting, trapping, or fishing. Farmers, for example, typically drained swamps next to their fields so as to gain more land usable for planting crops, both historically, and to a lesser extent, presently. On the other hand, swamps can (and do) play a beneficial ecological role in the overall functions of the natural environment and provide a variety of resources that many species depend on. Swamps and other wetlands have shown to be a natural form of flood management and defense against flooding. In such circumstances where flooding does occur, swamps absorb and use the excess water within the wetland, preventing it from traveling and flooding surrounding areas.[2] Dense vegetation within the swamp also provides soil stability to the land, holding soils and sediment in place whilst preventing erosion and land loss. Swamps are an abundant and valuable source of fresh water and oxygen for all life, and they are often breeding grounds for a wide variety of species. Floodplain swamps are an important resource in the production and distribution of fish.[10] Two thirds of global fish and shellfish are commercially harvested and dependent on wetlands.[2]
Impacts and conservation
Historically, humans have been known to drain and/or fill swamps and other wetlands in order to create more space for human development and to reduce the threat of diseases borne by swamp insects. Wetlands are removed and replaced with land that is then used for things like agriculture, real estate, and recreational uses. Many swamps have also undergone intensive logging and farming, requiring the construction of drainage ditches and canals. These ditches and canals contributed to drainage and, along the coast, allowed salt water to intrude, converting swamps to marsh or even to open water.[1] Large areas of swamp were therefore lost or degraded. Louisiana provides a classic example of wetland loss from these combined factors.[11] Europe has likely lost nearly half its wetlands.[12] New Zealand lost 90 percent of its wetlands over a period of 150 years.[13] Ecologists recognize that swamps provide ecological services including flood control, fish production, water purification, carbon storage, and wildlife habitats.[1] In many parts of the world authorities protect swamps. In parts of Europe and North America, swamp restoration projects are becoming widespread.[3][14] The United States government began enforcing stricter laws and management programs in the 1970s in efforts to protect and restore these ecosystems.[2] Often the simplest steps to restoring swamps involve plugging drainage ditches and removing levees.[1]
Conservationists work to preserve swamps such as those in northwest Indiana in the United States Midwest that were preserved as part of the Indiana Dunes.[15][16][17]
Notable examples
Swamps can be found on all continents except Antarctica.[18]
The largest swamp in the world is the Amazon River floodplain, which is particularly significant for its large number of fish and tree species.[19][20][21]
In Asia, tropical peat swamps are located in mainland East Asia and Southeast Asia. In Southeast Asia, peatlands are mainly found in low altitude coastal and sub-coastal areas and extend inland for distance more than 100 km (62 mi) along river valleys and across watersheds. They are mostly to be found on the coasts of East Sumatra, Kalimantan (Central, East, South and West Kalimantan provinces), West Papua, Papua New Guinea, Brunei, Peninsular Malaya, Sabah, Sarawak, Southeast Thailand, and the Philippines (Riley et al.,1996). Indonesia has the largest area of tropical peatland. Of the total 440,000 km2 (170,000 sq mi) tropical peat swamp, about 210,000 km2 (81,000 sq mi) are located in Indonesia (Page, 2001; Wahyunto, 2006).
The world's largest wetlands include significant areas of swamp, such as in the Amazon and Congo River basins.[21] Further north, however, the largest wetlands are bogs.
^ abcdKeddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p.
^ abcdef"swamp". National Geographic Society. 2011-01-21. Archived from the original on 2021-03-03. Retrieved 2019-09-26.
^ abHughes, F.M.R. (ed.). 2003. The Flooded Forest: Guidance for policy makers and river managers in Europe on the restoration of floodplain forests. FLOBAR2, Department of Geography, University of Cambridge, Cambridge, UK. 96 p.
^ abcdMitsch, W.J., & Gosselink, J.G.(2015). Wetlands. Hoboken, NJ: John Wiley & Sons Inc.
^"Linnaistensuo Mire". Visit Lahti. Lahti Region. Archived from the original on 1 December 2021. Retrieved 18 November 2020.
^Lowe-McConnell, R. H. (1975). Fish Communities in Tropical Fresh waters: Their Distribution, Ecology and Evolution. London: Long man
^Keddy, P.A., D. Campbell, T. McFalls, G. Shaffer, R. Moreau, C. Dranguet, and R. Heleniak. 2007. The wetlands of lakes Pontchartrain and Maurepas: past, present and future. Environmental Reviews 15: 1–35.
^Dugan, P. (ed.) 2005. Guide to Wetlands. Buffalo, New York. Firefly Books. 304 p.
^Peters, M. and Clarkson, B. 2010. Wetland Restoration: A Handbook for New Zealand Freshwater Systems. Manaaki Whenua Press, Lincoln, N.Z. ISBN978-0-478-34707-4 (online)
^Environment Canada. 2004. How Much Habitat is Enough? A Framework for Guiding Habitat Rehabilitation in Great Lakes Areas of Concern. 2nd ed. 81 p.
^Conner, W. H. and Buford, M. A. (1998). Southern deepwater swamps. In Southern Forested Wetlands: Ecology and Management, eds. M. G. Messina and W. H. Conner, pp. 261–87. Boca Raton, FL: Lewis Publishers.
^Reuss, M. (1998). Designing the Bayous: The Control of Water in the Atchafalaya Basin 1800–1995. Alexandria, VA: U.S. Army Corps of Engineers Office of History.
^Watson, Geraldine Ellis (2006) Big Thicket Plant Ecology: An Introduction, Third Edition (Temple Big Thicket Series #5). University of North Texas Press. Denton, Texas. 152 pp. ISBN978-1574412147
^Nowell, K.; Jackson, P., eds. (1996). "Panthera Onca". Wild Cats. Status Survey and Conservation Action Plan(PDF). Gland, Switzerland: IUCN/SSC Cat Specialist Group. IUCN. pp. 118–302. Archived(PDF) from the original on 2019-02-05. Retrieved 2015-09-07.