water. Plants and animals not physiologically adapted to a water-saturated 

 environment are severely stressed in wetland habitats, and consequently do 

 not comoete well with more water- tolerant species. 



Wetlands, as defined by the U.S. Fish and Wildlife Service, either: (1) 

 suDport predominantly wetland vegetation (hydrophytes) at least periodically; 

 and/or (2) have a substrate of primarily undrained, periodically anaerobic 

 (hydric) soil; and/or (3) have a nonsoil (bedrock, gravel, peat, etc.) 

 substrate saturated with or covered by water during at least some of the 

 growing season each year. The upper limit of a wetland is delineated by the 

 border" between predominantly hydrophytic (very wet) and mesophytic (average 

 moisture) or xerophytic (arid) plant cover, the transition between hydric and 

 nonhydric soils, and, in areas without plant cover or soil, the upper limit 

 of land which is covered by or saturated with water at some time each year. 



The lower limit of wetlands in saltwater (marine and estuarine) systems 

 is defined as the elevation of the extreme low water of spring tide. In 

 freshwater systems such as rivers (riverine), lakes (lacustrine), and 

 nontidal marshes (pal ustrine) , the lower limit is defined as the depth to 

 which emergents grow or 2 m (6.6 ft) whichever is deeper. 



For this coastal Alabama study, three categories of wetlands are mapped: 

 estuarine intertidal emergent wetland, palustrine emergent wetlands, and the 

 combination of palustrine forested and palustrine scrub-shrub wetland. 



Estuaries are defined as either deepwater or adjacent tidal wetlands that 

 have some access to the open ocean, although the saltwater is at least occa- 

 sionally diluted by freshwater runoff from land. Some estuaries actually 

 have higher salinities than the open ocean due to evaporation in enclosed 

 bays, but most have lower salinities. Estuaries are considered to extend 

 UDStream to the point where ocean-derived salts measure less than 0.5 part 

 per thousand (ppt) during average annual low flow. The seaward border of an 

 estuary may be the limit of seawater continuously diluted by freshwater run- 

 off, the seaward limit of wetland plants, or an imaginary line closing a 

 river, bay, or sound. Estuarine systems are divided into the subtidal sub- 

 system, which is continuously submerged, and the intertidal subsystem, which 

 is alternately exposed and submerged by tidal changes, and its associated 

 splash zone. 



Palustrine areas include tidal areas with ocean-derived salinities of 

 less than 0.5 ppt during average annual low flow and nontidal wetlands that 

 are dominated by trees, shrubs, persistent emergent vegetation, or emergent 

 mosses or lichens. Wetlands lacking such vegetation are designated 

 palustrine if they have an ocean-derived salinity of less than 0.5 ppt, have 

 an area of less than 8 ha (20 acres), lack active wave-formed or bedrock 

 shoreline features, and are less than 2 m (6.6 ft) deep at low water. The 

 palustrine classification includes areas traditionally called swamp, marsh, 

 fen, bog, and prairie. 



The dominant plant cover in emergent wetlands, whether estuarine or palu- 

 strine, is erect, rooted, herbaceous hydrophytes, excludinn mosses and 

 lichens. This vegetation is mostly perennial and is present for most of the 



