WETLANDS AND DEEPWATER 

 HABITATS 



Concepts and Definitions 



Marshes, swamps, and bogs have been well-known 

 terms for centuries, but only relatively recently have 

 attempts been made to group these landscape units 

 under the single term "wetlands." This general term 

 has grown out of a need to understand and describe the 

 characteristics and values of all types of land, and to 

 wisely and effectively manage wetland ecosystems. 

 There is no single, correct, indisputable, ecologically 

 sound definition for wetlands, primarily because of the 

 diversity of wetlands and because the demarcation be- 

 tween dry and wet environments lies along a con- 

 tinuum. Because reasons or needs for defining 

 wetlands also vary, a great proliferation of definitions 

 has arisen. The primary objective of this classification 

 is to impose boundaries on natural ecosystems for the 

 purposes of inventory, evaluation, and management. 



Wetlands 



In general terms, wetlands are lands where satura- 

 tion with water is the dominant factor determining the 

 nature of soil development and the types of plant and 

 animal communities living in the soil and on its 

 surface. The single feature that most wetlands share is 

 soil or substrate that is at least periodically saturated 

 with or covered by water. The water creates severe 

 physiological problems for all plants and animals 

 except those that are adapted for life in water or in sat- 

 urated soil. 



WETLANDS are lands transitional between terrestrial 

 and aquatic systems where the water table is usually 

 at or near the surface or the land is covered by shallow 

 water. For purposes of this classification wetlands 

 must have one or more of the following three attri- 

 butes: (1) at least periodically, the land supports 

 predominantly hydrophytes; 2 12) the substrate is pre- 

 dominantly undrained hydric soil; 3 and (3) the substrate 

 is nonsoil and is saturated with water or covered bv 

 shallow water at some time during the growing season 

 of each year. 



The term wetland includes a variety of areas that fall 

 into one of five categories: (1) areas with hydrophytes 

 and hydric soils, such as those commonly known as 

 marshes, swamps, and bogs; (2) areas without hydro- 

 phytes but with hydric soils— for example, flats where 



2 The U.S. Fish and Wildlife Service is preparing a list of 

 hydrophytes and other plants occurring in wetlands of the 

 United States. 



3 The U.S. Soil Conservation Service is preparing a pre- 

 liminary list of hydric soils for use in this classification 

 system. 



drastic fluctuation in water level, wave action, tur- 

 bidity, or high concentration of salts may prevent the 

 growth of hydrophytes; (3) areas with hydrophytes but 

 nonhydric soils, such as margins of impoundments or 

 excavations where hydrophytes have become estab- 

 lished but hydric soils have not yet developed; (4) areas 

 without soils but with hydrophytes such as the 

 seaweed-covered portion of rocky shores; and (5) 

 wetlands without soil and without hydrophytes, such 

 as gravel beaches or rocky shores without vegetation. 



Drained hydric soils that are now incapable of sup- 

 porting hydrophytes because of a change in water 

 regime are not considered wetlands by our definition. 

 These drained hydric soils furnish a valuable record of 

 historic wetlands, as well as an indication of areas that 

 may be suitable for restoration. 



Wetlands as defined here include lands that are 

 identified under other categories in some land-use 

 classifications. For example, wetlands and farmlands 

 are not necessarily exclusive. Many areas that we 

 define as wetlands are farmed during dry periods, but 

 if they are not tilled or planted to crops, a practice that 

 destroys the natural vegetation, they will support 

 hydrophytes. 



Deepwater Habitats 



Deepwater Habitats are permanently flooded 

 lands lying below the deepwater boundary of wetlands. 

 Deepwater habitats include environments where sur- 

 face water is permanent and often deep, so that water, 

 rather than air, is the principal medium within which 

 the dominant organisms live, whether or not they are 

 attached to the substrate. As in wetlands, the domi- 

 nant plants are hydrophytes; however, the substrates 

 are considered nonsoil because the water is too deep 

 to support emergent vegetation (U. S. Soil Conserva- 

 tion Service, Soil Survey Staff 1975). 



Wetlands and Deepwater Habitats are defined sepa- 

 rately because traditionally the term wetland has not 

 included deep permanent water; however, both must 

 be considered in an ecological approach to classifi- 

 cation. We define five major systems: Marine, Estua- 

 rine, Riverine, Lacustrine, and Palustrine. The first 

 four of these include both wetland and deepwater 

 habitats but the Palustrine includes only wetland 

 habitats. 



Limits 



The upland limit of wetland is designated as (1) the 

 boundary between land with predominantly hydro- 

 phytic cover and land with predominantly mesophytic 

 or xerophytic cover; (2) the boundary between soil that 

 is predominantly hydric and soil that is predominantly 

 nonhydric; or (3) in the case of wetlands without vege- 

 tation or soil, the boundary between land that is 



