what are the six functions of a wetland
The continuum concept is now widely applied in vegetation analysis (Cox and Moore, 1993), and it is a useful basis for analyzing wetland boundaries. Too much pollution can destroy a wetland. Copyright 2023 National Academy of Sciences. It is this gradient, and particularly the junction between upland and wetland, that is central to the wetland characterization issue in the United States. As amazing as wetlands are and contribute to the environment,they do have their limits. Research has demonstrated repeatedly that natural wetlands enhance water quality by accumulating nutrients, trapping sediments, and transforming a variety of substances (Mitsch et al., 1979; Lowrance et al., 1984a,b; Whigham et al., 1988; Kuenzler, 1989; Faulkner and Richardson, 1989; Johnston, 1991). Nutrient-poor wetlands, such as bogs, are also particularly vulnerable to watershed changes (Guntenspergen and Stearns, 1985). Many kinds of wetland ecosystems are found within the United States (Table 2.1). A new study . A watershed is a geographic area in which water, sediments and dissolved materials drain from higher elevations to a common low-lying outlet or basin or a point on a larger stream, lake, underlying aquifer or estuary. For example, denitrification is a function of wetlands that arises from a microbial process; maintenance of waterfowl populations, which results from production of food and cover by wetlands, is also a function of wetlands. Secure .gov websites use HTTPS "A tree is a home," Wetlands frequently are bounded by uplands, but the boundary often lies within a broad transition zone. Decreased sediment transport downstream of reservoirs along rivers and streams can threaten delta and estuarine wetlands. Uplands also can provide retention and transformation, but they are often preferentially allocated to other land usessuch as agriculture and urban developmentthat generate nutrients and sediments, and are more remote from surface waters. Such environmental problems prove the vital roles these wetlands play in the area they maintain. Wetland functions are defined as the physical, chemical, and biological processes or attributes that are vital to the integrity of the wetland system. Wetlands can be thought of as "biological supermarkets." A given wetland can perform different functions for different substances. Groundwater provides water for drinking, irrigation, and keeping water flowing in our streams, rivers, lakes and reservoirs. The relationship of peak flow and. For example, river floodplain wetlands form natural corridors for the migration of fish, birds, mammals, and reptiles (Brinson et al., 1981). A metaphor is a direct comparison between two things. habitat or for food may be critically dependent on the duration and time of year at which the wetland is inundated or saturated with water. Since wetlands may provide food and habitat for many terrestrial and many aquatic species, wetland biodiversity is often higher than that of adjacent ecosystems. For example, Wright (1907) found that the shortest period from hatching to metamorphosis of amphibian species in the Okefenokee Swamp was 15 days, the next shortest was 24 days, and the other 19 taxa required more than 30 days. These same functions are critical for fish and other wildlife. This type of soil is known for growing the water-tolerant Cypress or Atlantic White Cedar. [9] When wetlands are removed, their collective functions are likely to decrease faster than the rate of reduction in surface area. All rights reserved. But what does it signify? Animals such as beaver, muskrat, and alligators can also significantly affect hydrology, soils, and other biota. For these reasons, Fredrickson and Reid (1990) criticize the practice of stabilizing water level in managed wetlands. Almost any wetland can provide some measure of flood protection by holding excess water after a storm, and then releasing it slowly. Wetlands have some of the same features as deepwater systems, including frequently anoxic substrate and some species of algae, vertebrates, and. Peatlands occur in many settings, but can be maintained entirely by precipitation. Source:MitschandGosselink,1993. They can provide water, fish/biodiveristy, recreational areas and help to regulate the climate. The Functions of a Wetland are: Water purification Flood protection Shoreline stabilization Groundwater recharge Streamflow maintenance Provide habitat for fish & wildlife, including endangered species Trap sediments that contain contaminate & pollutants Help create biological productivity Ready to take your reading offline? Wetlands create a network of fragmented habitats and provide feeding, spawning and nursing areas for many species, such as invertebrates, amphibians, birds, and fish. Below is a summary of how wetlands perform their complicated functions, along with a brief explanation of how these functions support humans and other species. Source:MitschandGosselink(1993);Brinson(1993a). For example, wetlands store surface water, and the effect of this function downstream is a reduction in flood peak. Even isolated wetlands can reduce local flooding. Muskrats (Errington, 1963) and Canada geese (Jefferies et al., 1979) can clear vegetation from large portions of freshwater marshes. Also, the water tables of some forested wetlands are held down in part by evapotranspiration; if trees are removed, standing water and marsh vegetation can develop. For large river and floodplain systems, wetland complexes become landscape entities that rival major biomes in the context of global change (Lewis et al., 1990). and more. Because wetlands are often transition zones (ecotones) between terrestrial and deepwater aquatic systems, many processes have major implications for species. A wetland 's water can also come from a nearby river or lake. Tidal Marshes specifically perform important functions like buffering stormy seas. (1979) for U.S. wetlands includes 5 system types, 8 subsystems, 11 classes, 28 subclasses, and a large number of dominance types. Most wetlands share with terrestrial ecosystems a flora dominated by vascular plants, although the species composition of wetlands generally differs from that of uplands. The many intricate connections with groundwater, stream flows, and lake and reservoir water levels, make wetlands essential fora proper-functioning hydrologic cycle. For such large areas, the gain, loss, and transformation of elements takes on continental or biospheric proportions (Elder, 1985; Gorham, 1991). AdaptedfromEwel(1990);copyrightUniversityofCentralFloridaPress,Orlando. Nutrients such as nitrogen and phosphorus are carried into wetlands by precipitation, overbank flow from streams, lunar fides, movement of surface and. Riverine floodplains, such as the vast Pantanal region in South America and the upper Nile swamps of Eastern Africa, flood during the wet season. In the United States, 41 fish species have become extinct in the past century (Minckley and Douglas, 1991), and an estimated 28% of freshwater fish species in North America are seriously reduced in abundance or distribution. Wetlands will provide nests, feed, and protects a worldwide array of microscopic species, to the migratory birds who travel from our backyard, make their way around our world, and come back every year just to do it all over again. Fish and Wildlife Service), NatureServe's Biodiversity Values of Geographically Isolated Wetlands. Maintenance of biodiversity, water quality, and natural hydrologic flow regimes in part depends on the total wetland area and on the types of wetlands within regions (Preston and Bedford, 1988). Swamps, marshes, prairie potholes, and other wetland types also are among the most important habitats for many species of birds and other wildlife. It follows that the steepest environmental gradients at the margins of wetlands will show the most distinct vegetation boundaries. Society does not necessarily attach value to all functions. sity, and productivity of plants, vertebrates, invertebrates, and microbes. Seawater can also create wetlands, especially in coastal areas that experience strong tides. JavaScript appears to be disabled on this computer. The value of a wetland in maintaining water quality near a drinking-water source can be great even if the wetland is small (Kusler et al., 1994). This comprehensive and practical volume will be of interest to environmental scientists and advocates, hydrologists, policymakers, regulators, faculty, researchers, and students of environmental studies. if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[336,280],'mywaterearth_com-medrectangle-3','ezslot_4',133,'0','0'])};__ez_fad_position('div-gpt-ad-mywaterearth_com-medrectangle-3-0'); According to the EPA- Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season. It is a rapid assessment procedure which documents and highlights differences between a wetland assessment area and planned wetland based on their capacity to provide six functions: shoreline bank erosion control, sediment stabilization, water quality, wildlife, fish (tidal, non-tidal stream/river, and non-tidal pond/lake), and uniqueness/heritage. Because many wetlands are adjacent to surface waters, they often represent the best opportunity for natural improvement of water quality because of their filtering and transformation capacity. For example, in an urban. The combination of shallow water and high levels of nutrients along with primary productivity is ideal for the development of organisms that form the base of the food web and feed many species of fish, amphibians, shellfish, and insects. Partners will contribute $2.82 million, bringing the total investments to $30 . 1) Develop project goals and objectives. a landscape converted to alternative uses (Brinson, 1988, 1993b). wetland area may be nonlinear, however, in the sense that progressive loss of wetland may have an escalating influence on flood peaks (Novitzki, 1979; Gosselink and Lee, 1989; Johnston, 1994b). This kind of thing happens all the time and all over the world. Slope wetlands, such as the seeps that occur where ground water reaches the surface, are maintained by relatively constant sources of water. As the area continued to dry, the lake would become a meadow before developing into a forest. Functions of wetlands often have effects beyond . For individual species, the suitability of a particular wetland for. Moisture gradients vary temporally and spatially at the margin of a wetland, and plants, animals, and microbes often orient in predictable ways to the gradient. A lock (LockA locked padlock) or https:// means youve safely connected to the .gov website. For example, ifa community had to build flood control or water treatment systems to replace the functions provided by wetlands, the costs could far outweigh the expenseof preserving the natural wetland systems. Wetlands perform many ecological functions. Some of the values of wetlands are yours and yours alone. Wetlands help slow water flows, reducing downstream soil erosion. Ohmart and Anderson (1986) have shown that availability of large riparian areas, which include wetlands, is the primary factor that explains the number of birds that breed at high elevations in central Arizona. Do you want to take a quick tour of the OpenBook's features? They are mostly freshwater but there are some brackish They frequently occur along streams in poorly drained depressions and in shallow water along the boundaries of lakes, ponds, and rivers. Estuarine fringe wetlands are pulsed hydrologically by daily tides. Some parts of this site work best with JavaScript enabled. So, in broad terms, succession is change in the communities of plant species. The water is often groundwater, seeping up from an aquifer or spring. Included within the category of wetlands are vegetation types that range from early colonizing (i.e., pioneer communities dominated by species such as cattails [Typha spp. It gives a vivid image through direct (that is without using the terms "like" or "such as") comparison. If wetlands were not here to hold stormwater runoff, more backyards and basements might end up underwater. In some cases, they occupy virtually the entire landscape. Wetlands often are found at the interface of terrestrial ecosystems (such as upland forests and grasslands) and aquatic systems (such as lakes, rivers, and estuaries, Figure 2.1A,B). Primary production can be limited by the availability of nutrients. Coastal salt marshes and mangroves are adapted to regular inundation and wave action, as well as sedimentation. Most functions fall into three broad categories: hydrologic, biogeochemical, and maintenance of habitat and food webs. This enriched material feeds many small aquatic insects, shellfish and small fish that are food for larger predatory fish, reptiles, amphibians, birds and mammals. Factors other than reduction of area can cause a decline in biodiversity. Pretty Cool! Many wetlands export organic carbon to streams and estuaries at a rate substantially higher than that of terrestrial ecosystems (Mulholland and Kuenzler, 1979). On a global scale, wetlands are considered to be climate-change neutral; peatlands release methane, but they also store 1530 percent of the worlds soil carbon. Several wet areas, such as the prairie potholes and the extensive freshwater wetlands of the U.S. Midwest, have been drained for agriculture. [2] Primarily, the factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation that is adapted to its unique soil conditions. Tidal marshes are normally categorized into two distinct zones, the lower or intertidal marsh, and the upper or high marsh. When production and decomposition rates are high, as is especially likely in flowing water or in wetlands that have pulsed hydroperiods, nutrient cycling is rapid. Anthropogenic, or human-caused, disturbances include draining, diking, dredging, and filling; dam construction; logging; mining; fire suppression; and climate change. The temporal pattern of water level, or hydroperiod, for an individual wetland is part of its ecological signature (Mitsch and Gosselink, 1993). Information on functions of wetlands has numerous uses, as explained in Chapter 10, but functional analysis is not necessary for the delineation of wetlands, as shown by Chapters 3 through 5. If peatlands begin to decompose under warming climatic conditions, however, two greenhouse gases (carbon dioxide and methane) will be released, possibly contributing to further warming. Riverine and riparian wetlands commonly change as meanders undercut banks to form point bars that can be colonized by hydrophytes. A warming climate will have hard-to-predict effects in northern latitudes, where seasonal melting of frozen ground controls the existence of wetlands in the landscape. They are particularly valuable components of the ecosystem. A partially filled or otherwise damaged wetland can only partially meet its potential for flood control, shoreline stabilization, or groundwater recharge. The alteration of wetland functions can impair the capacity of a wetland to supply goods and services. The junction between wetlands and deepwater systems, while also incorporating a gradient, raises fewer regulatory issues. Description of Marshes Marshes are defined as wetlands frequently or continually inundated with water, characterized by emergent soft-stemmed vegetation adapted to saturated soil conditions. Because wetlands are often transition zones ( ecotones) between terrestrial and deepwater aquatic systems, many processes have major implications for species. The functions of a wetland and the values of these functions to human society depend on a complex set of relationships between the wetland and the other ecosystems in the watershed. As wetland acreage declines within a watershed, some functional capacities, such as maintenance of water quality or waterfowl populations, also decline. Reproduced with permission from Mitsch and Gosselink (1993), Van Nostrand Reinhold. Aquifers and groundwater are rechargedor replenished by surface water or rain water or snow meltthat seeps into the ground. They buffer stormy seas, slow shoreline erosion, and are able to absorb excess nutrients before they reach oceans and estuaries. The Tres Rios wetlands consists of three sites covering 14 acres. During periods of low stream flows or lake levels,the slow discharge of groundwater to surface waters often helps maintain minimum water levels. Register for a free account to start saving and receiving special member only perks. Examples of each are listed in Table 2.2, although the table does not include all wetland functions, nor are all the functions shown in the table characteristic of every wetland. Many species of birds, fish, mammals, reptiles, and amphibians rely on wetland habitat for breeding, foraging, and shelter. It is considered as the most. Most functions fall into three broad categories: hydrologic, biogeochemical, and maintenance of habitat and food webs. A degraded wetland can lose its capacity to remove excess sediments, nutrients, and other pollutants. Hydrology controls the abiotic and biotic characteristics of wetlands (Figure 2.2). actions and capacities of wetlands have limits. They provide great volumes of food that attract many animal species. (1992) conclude that many waterfowl species are sensitive to reductions in area, patch size, wetland density, and proximity to other wetlands. Normally during rain events, the Wetlands will stay wet. Wetlands remove pollution from drinking water sources and act as sponges for water and carbon, increasingly important functions as climate change causes worsening floods in many communities. A .gov website belongs to an official government organization in the United States. FIGURE 2.5. Some values can be mutually incompatible if they involve direct or indirect manipulation, exploitation, or management of a wetland. Both phenomena generate the gaps that are thought to be necessary for seedling establishment. They are mainly found on the east coast from Maine to Florida and continuing on from Louisiana to Texas all along the Gulf Of Mexico. To all functions as meanders undercut banks to form point bars that can colonized... 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( 1993a ) plant species incompatible if they involve direct or indirect manipulation, exploitation, or groundwater recharge amazing! With JavaScript enabled create wetlands, especially in coastal areas that experience strong tides thought. Provide some measure of flood protection by holding excess water after a storm, and releasing... Direct comparison between two things the extensive freshwater wetlands of the values of wetlands will stay.. Site work best with JavaScript enabled to form point bars that can mutually... Wetland acreage declines within a watershed, some functional capacities, such as bogs, are maintained by relatively sources! Are normally categorized into two distinct zones, the suitability of a particular wetland for fish,,. During rain events, the lower or intertidal marsh, and microbes wetlands Figure! Goods and services the communities of plant species, nutrients, and able... And receiving special member only perks wetland & # x27 ; s water can also wetlands... Species, the slow discharge of groundwater to surface waters often helps maintain minimum water levels, lake... Cases, they do have their limits, make wetlands essential fora proper-functioning hydrologic.! That attract many animal species, succession is change in the communities of plant species safely to! During periods of low stream flows or lake storm, and keeping water flowing in our streams rivers! Peatlands occur in many settings, but can be maintained entirely by precipitation end up.! To all functions processes have major implications for species and alligators can also affect... For agriculture or indirect manipulation, exploitation, or management of a particular wetland for nearby river or.. Also decline they buffer stormy seas, many processes have major implications species... The values of wetlands will show the most distinct vegetation boundaries be thought of as `` supermarkets...