32 • Wetlands: Their Use and Regulation 



tered scrublands. On the eastern shore of Florida 

 and along the Louisiana coast, mangroves are 

 found behind barrier islands and on the shores of 

 protected coastlines. 



Tidal Freshwater Marshes 



Tidal freshwater marshes occur in virtually every 

 coastal State but are most abundant in the estuaries 



of the mid- Atlantic coast and along the coasts of 

 Louisiana and Texas. Dominant intertidal plants 

 include a mixture of grasses and broadleaf species, 

 such as arrow arum, spatterdock, pickerel weed, 

 and arrowhead, which form rather complex multi- 

 layered plant zones. The upper marsh may have 

 from 20 to 50 species of grasses, shrubs, ferns, and 

 herbaceous plants (11). 



GEOGRAPHIC DISTRIBUTION OF WETLAND TYPES 



The various wetland types described in the pre- 

 vious section are distributed unevenly across the 

 United States. The regions of the United States with 

 high concentrations of the various types are iden- 



tified in table 3. The regions described are based 

 on Hammond's Physical Subdivisions (fig. 3), 

 which are the same as those used in Chapter 5: 

 Wetland Trends. 



Table 3.— Locations of Various Wetland Types in the United States 



Wetland type Primary regions States 



Inland freshwater marsh Dakota-Minnesota drift and lake bed (8); North Dakota, South Dakota, Nebraska, 



Upper Midwest (9); and Gulf Coastal Minnesota, Florida 



Flats (4) 



Inland saline marshes Intermontane (12); Pacific Mountains (13) Oregon, Nevada, Utah, California 



Bogs Upper Midwest (9); Gulf-Atlantic Rolling Wisconsin, Minnesota, Michigan, Maine, 



Plain (5); Gulf Coastal Flat (4); and Florida, North Carolina 



Atlantic Coastal Flats (3) 



Tundra Central Highland and Basin; Arctic Alaska 



Lowland; and Pacific Mountains 



Shrub swamps Upper Midwest (9); Gulf Coastal Flats (4) Minnesota, Wisconsin, Michigan, Florida, 



Georgia, South Carolina, North Carolina, 

 Louisiana 



Wooded swamps Upper Midwest (9); Gulf Coastal Flats (4); Minnesota, Wisconsin, Michigan, Florida, 



Atlantic Coastal Flats (3); and Lower Georgia, South Carolina, North Carolina, 



Mississippi Alluvial Plain (6) Louisiana 



Bottom land hardwood Lower Mississippi Alluvial Plain (6); Louisiana, Mississippi, Arkansas, 



Atlantic Coastal Flats (3); Gulf-Atlantic Missouri, Tennessee, Alabama, Florida, 

 Rolling Plain (5); and Gulf Coastal Georgia, South Carolina, North Carolina, 



Flats (4) Texas 



Coastal salt marshes Atlantic Coastal Zone (1); Gulf Coastal All Coastal States, but particularly the 



Zone (2); Eastern Highlands (7); Pacific Mid- and South Atlantic and Gulf Coast 

 Moutains (13) States 



Mangrove swamps Gulf Coastal Zone (2) Florida and Louisiana 



Tidal freshwater wetlands Atlantic Coastal Zone (1) and Flats (3); Louisiana, Texas, North Carolina, Virginia, 



Gulf Coastal Zone (2) and Flats (4) Maryland, Delaware, New Jersey, 

 Georgia, South Carolina 



SOURCE: This table is based on maps from Samuel P, Shaw and C. Gordon Fredine, "Wetlands of the United States: Their Extent and Their Value to Waterfowl and 

 other Wildlife, " Fish and Wildlife Service, US Department of the Interior, Circular 39, 1956. 



