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<br />91 <br /> <br />animal rather than plant communities. Uke"he, the definition ill slightly <br />more complex because of the inclusion of additional te'chnical terns such as <br />hydrophvte and hydric soils. - ~drophyte is defined aSI any plant i~rowi~g,.1n <br />water or on a substrate that is at least periodically def1cl,el\~,1i1.,0~n.n as <br />s result'bf~ exeess1l1l! Wa ter content. Hydr1(~ soU'b clldined," 1CI11l.liliir is <br />wet long enough to pedodically produce anaerobic co!latUim. (t..e." abienc. <br />of oxygen), thereby influencing the growt h (If plants a.nd aenerall~'.)illli tin'g <br />vegetation to wetland adapted plants such as willows (Sal1x), rushes" <br />(Juncus), sedges (Carex), etc. <br /> <br />Wetlands as defined by the USF & WS include lands that are currently <br />under cultivation. That is, wetlands and farm lands are not necessarily <br />exclusive. Many areas defined as wetlands are farmed during dry pe:riods but <br />if they are not tilled, cultivated, planted, heavily grazed, or subjected to <br />practices that destroy the natural vegetation, the land will suppot't <br />hydrophytes and revert to wetlands (Cowardin et al., 1979). <br /> <br />The dry land or upland limit to a wetland is designated as 1) the <br />boundary between land with predolllinantly mes~'phyt1c or xerophytic <br />vegetational cover and land with predominatl:v hydrophytic vegetational <br />cover; 2) the boundary between soil that is predominantly nonhydric, and soil <br />that is predolll1nantly hydric; or 3) in the cue of wetlands 1Iithout <br />vegetation or soil, the boundary between land that is flooded or saturated <br />at some time each year and land that is not. <br /> <br />Current practice distinguishes between "wetlands" and "deepwater <br />habitats." Deepwater habitats are permanently flooded areas or lands lying <br />below the deepwater boundary of wetlands. TIle dividing boundary between <br />inland wetlands and deepwater habit~t has been set at 2 meters (6.6 feet). <br />This depth was selected because -it is the lIaltimwa depth at which "emergent <br />plants" normally grow. This is based on the faet that "emergents" are not <br />true aquatic plants, but "amphibious," plantlladapted f,)[ growth in both <br />permanently flooded and nonflooded or wet soBs" When the emergents, <br />shrubs, or trees grow beyond the 2-.. low watE,r mark, at any time, their. deep <br />water edge is the boundary. <br /> <br />Wetland COl!lponer~~, <br /> <br />Wetlands can be characterized in terms of hydrology, vegetatioll, and <br />s oils. The three components vary geographic~llly, and illteract with each <br />other and with topography and geology to give wetlands their distinctive <br />characteristics. <br /> <br />Water <br /> <br />All natural wetland functions are a res~llt of, or ,Ire closely :related <br />to, the wetland water cycle and the hydrological cycle :ls the chief outside <br />or "forcing" function that controls wetland structure and function <br />(Gosselink and Turner 1978). From an energetic analysis, the hydrological <br />