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 between dry and wet environments lies 

 along a continuum. Because reasons or needs for defin- 

 ing 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 pur- 

 poses of inventory, evaluation, and management. 



tion of salts may prevent the growth of hydrophytes; (3) 

 areas with hydrophytes but nonhydric soils, such as 

 margins of impoundments or excavations where hydro- 

 phytes have become established 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 support- 

 ing 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 iden- 

 tified under other categories in some land-use classifica- 

 tions. For example, wetlands and farmlands are not 

 necessarily exclusive. Many areas that we define as wet- 

 lands 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. 



Wetlands 



In general terms, wetlands are lands where saturation 

 with water is the dominant factor determining the nature 

 of soil development and the types of plant and animal com- 

 munities 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 saturated 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 attributes: (1) at least 

 periodically, the land supports predominantly hydro- 

 phytes; 1 (2) the substrate is predominantly undrained 

 hydric soil; 2 and (3) the substrate is nonsoil and is 

 saturated with water or covered by 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 hydrophytes but with 

 hydric soils— for example, flats where drastic fluctuation 

 in water level, wave action, turbidity, or high concentra- 



■The U.S. Fish and Wildlife Service is preparing a list of hydro- 

 phytes and other plants occurring in wetlands of the United 

 States. 



2 The U.S. Soil Conservation Service is preparing a preliminary 

 list of hydric soils for use in this classification system. 



Deepwater Habitats 



Deepwater Habitats are permanently flooded lands 

 lying below the deepwater boundary of wetlands. Deep- 

 water habitats include environments where surface 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 dominant plants are hydro- 

 phytes; however, the substrates are considered nonsoil 

 because the water is too deep to support emergent vegeta- 

 tion (U.S. Soil Conservation Service, Soil Survey Staff 

 1975). 



Wetlands and deepwater habitats are defined separately 

 because traditionally the term wetland has not included 

 deep permanent water; however, both must be considered 

 in an ecological approach to classification. We define five 

 major Systems: Marine, Estuarine, 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 boun- 

 dary between land with predominantly hydrophytic cover 

 and land with predominantly mesophytic or xerophytic 

 cover; (2) the boundary between soil that is predominant- 

 ly hydric and soil that is predominantly nonhydric; or (3) 

 in the case of wetlands without vegetation or soil, the 

 boundary between land that is flooded or saturated at 

 some time during the growing season each year and land 

 that is not. 



