It has been suggested that this article should be split into articles titled Swamp (wetland) and Swamp (woodland) . (discuss) (July 2023) |
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]
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]
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]
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]
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]
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]
The Sudd and the Okavango Delta [22] [23] are Africa's best known marshland areas. The Bangweulu Floodplains make up Africa's largest swamp.
The Mesopotamian Marshes [24] is a large swamp and river system in southern Iraq, traditionally inhabited in part by the Marsh Arabs.
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 Vasyugan Swamp is a large swamp in the western Siberia area of the Russian Federation. This is one of the largest swamps in the world, covering an area larger than Switzerland.
The Atchafalaya Swamp at the lower end of the Mississippi River is the largest swamp in the United States. It is an important example of the southern cypress swamp [25] but it has been greatly altered by logging, drainage, and levee construction. [26] Other famous swamps in the United States are the forested portions of the Everglades, Okefenokee Swamp, Barley Barber Swamp, Great Cypress Swamp and the Great Dismal Swamp. The Okefenokee is located in extreme southeastern Georgia and extends slightly into northeastern Florida. The Great Cypress Swamp is mostly in Delaware, but extends into Maryland on the Delmarva Peninsula. Point Lookout State Park on the southern tip of Maryland contains many swamps and marshes. The Great Dismal Swamp lies in extreme southeastern Virginia and extreme northeastern North Carolina. Both are National Wildlife Refuges. Another swamp area, Reelfoot Lake of extreme western Tennessee and Kentucky, was created by the 1811–12 New Madrid earthquakes. Caddo Lake, the Great Dismal and Reelfoot are swamps centered at large lakes. Swamps are often associated with bayous in the southeastern United States, especially in the Gulf Coast region. A baygall is a type of swamp found in the forest of the Gulf Coast states in the USA. [27] [28] [29]
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.
The Everglades is a natural region of flooded grasslands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee. Water leaving the lake in the wet season forms a slow-moving river 60 miles (97 km) wide and over 100 miles (160 km) long, flowing southward across a limestone shelf to Florida Bay at the southern end of the state. The Everglades experiences a wide range of weather patterns, from frequent flooding in the wet season to drought in the dry season. Throughout the 20th century, the Everglades suffered significant loss of habitat and environmental degradation.
A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor (anoxic) processes taking place, especially in the soils. Wetlands form a transitional zone between waterbodies and dry lands, and are different from other terrestrial or aquatic ecosystems due to their vegetation's roots having adapted to oxygen-poor waterlogged soils. They are considered among the most biologically diverse of all ecosystems, serving as habitats to a wide range of aquatic and semi-aquatic plants and animals, with often improved water quality due to plant removal of excess nutrients such as nitrates and phosphorus.
A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetland along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires. The unique water chemistry of fens is a result of the ground or surface water input. Typically, this input results in higher mineral concentrations and a more basic pH than found in bogs. As peat accumulates in a fen, groundwater input can be reduced or cut off, making the fen ombrotrophic rather than minerotrophic. In this way, fens can become more acidic and transition to bogs over time.
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials – often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; alkaline mires are called fens. A bayhead is another type of bog found in the forest of the Gulf Coast states in the United States. They are often covered in heath or heather shrubs rooted in the sphagnum moss and peat. The gradual accumulation of decayed plant material in a bog functions as a carbon sink.
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants. More in general, the word can be used for any low-lying and seasonally waterlogged terrain. In Europe and in agricultural literature low-lying meadows that require draining and embanked polderlands are also referred to as marshes or marshland.
Lake Pontchartrain is an estuary located in southeastern Louisiana in the United States. It covers an area of 630 square miles (1,600 km2) with an average depth of 12 to 14 feet. Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about 40 miles (64 km) from west to east and 24 miles (39 km) from south to north.
The Pearl River is a river in the U.S. states of Mississippi and Louisiana. It forms in Neshoba County, Mississippi from the confluence of Nanih Waiya and Tallahaga creeks, and has a meander length of 444 miles (715 km). The lower part of the river forms part of the boundary between Mississippi and Louisiana.
Caddo Lake is a 25,400-acre (10,300 ha) lake and bayou (wetland) on the border between Texas and Louisiana, in northern Harrison County and southern Marion County in Texas and western Caddo Parish in Louisiana. The lake is named after the Caddoans or Caddo, Native Americans who lived in the area until their expulsion by the United States in the 19th century. The US forced most of them to move west to Indian Territory.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes, ponds, rivers, streams, springs, bogs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic, lotic and wetlands. Freshwater ecosystems contain 41% of the world's known fish species.
The wetlands of Louisiana are water-saturated coastal and swamp regions of southern Louisiana, often called "Bayou".
The Atchafalaya Basin, or Atchafalaya Swamp, is the largest wetland and swamp in the United States. Located in south central Louisiana, it is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge. The river stretches from near Simmesport in the north through parts of eight parishes to the Morgan City southern area.
Hammock is a term used in the southeastern United States for stands of trees, usually hardwood, that form an ecological island in a contrasting ecosystem. Hammocks grow on elevated areas, often just a few inches high, surrounded by wetlands that are too wet to support them. The term hammock is also applied to stands of hardwood trees growing on slopes between wetlands and drier uplands supporting a mixed or coniferous forest. Types of hammocks found in the United States include tropical hardwood hammocks, temperate hardwood hammocks, and maritime or coastal hammocks. Hammocks are also often classified as hydric, mesic or xeric. The types are not exclusive, but often grade into each other.
Pocosin is a type of palustrine wetland with deep, acidic, sandy, peat soils. Groundwater saturates the soil except during brief seasonal dry spells and during prolonged droughts. Pocosin soils are nutrient-deficient (oligotrophic), especially in phosphorus.
A wet meadow is a type of wetland with soils that are saturated for part or all of the growing season which prevents the growth of trees and brush. Debate exists whether a wet meadow is a type of marsh or a completely separate type of wetland. Wet prairies and wet savannas are hydrologically similar.
Before drainage, the Everglades, a region of tropical wetlands in southern Florida, were an interwoven mesh of marshes and prairies covering 4,000 square miles (10,000 km2). The Everglades is both a vast watershed that has historically extended from Lake Okeechobee 100 miles (160 km) south to Florida Bay, and many interconnected ecosystems within a geographic boundary. It is such a unique meeting of water, land, and climate that the use of either singular or plural to refer to the Everglades is appropriate. When Marjory Stoneman Douglas wrote her definitive description of the region in 1947, she used the metaphor "River of Grass" to explain the blending of water and plant life.
Classification of wetlands has been a problematical task, with the commonly accepted definition of what constitutes a wetland being among the major difficulties. A number of national wetland classifications exist. In the 1970s, the Ramsar Convention on Wetlands of International Importance introduced a first attempt to establish an internationally acceptable wetland classification scheme.
A peatland is a type of wetland whose soils consist of organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. Peatlands are unusual landforms that derive mostly from biological rather than physical processes, and can take on characteristic shapes and surface patterning.
The Mississippi Alluvial Plain is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in seven U.S. states, though predominantly in Arkansas, Louisiana, and Mississippi. It parallels the Mississippi River from the Midwestern United States to the Gulf of Mexico.
Coastal erosion in Louisiana is the process of steady depletion of wetlands along the state's coastline in marshes, swamps, and barrier islands, particularly affecting the alluvial basin surrounding the mouth of the Mississippi River. In the last century, coastal Louisiana has lost an estimated 4,833 square kilometers (1,866 sq mi) of land, approximately the size of Delaware's land area. Coast wide rates of wetland change have varied from −83.5 square kilometers (−32.2 sq mi) to −28.01 square kilometers (−10.81 sq mi) annually, with peak loss rates occurring during the 1970's. One consequence of coastal erosion is an increased vulnerability to hurricane storm surges, which affects the New Orleans metropolitan area and other communities in the region. The state has outlined a comprehensive master plan for coastal restoration and has begun to implement various restoration projects such as fresh water diversions, but certain zones will have to be prioritized and targeted for restoration efforts, as it is unlikely that all depleted wetlands can be rehabilitated.
The North American Southern Coastal Plain is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in six U.S. states. The region stretches across the Gulf coast from eastern Louisiana to Florida, forms the majority of Florida, and forms the coastlines of Georgia and much of South Carolina. It has been divided into twelve Level IV ecoregions.