24 



We use the Modifiers mineral and organic in this 

 classification. Mineral soils and organic soils are differen- 

 tiated on the basis of specific criteria that are enumerated 

 in soil taxonomy (U.S. Soil Conservation Service, Soil 

 Survey Staff 1975:13-14, 65). These criteria are restated 

 in our Appendix D for ready reference. If a more detailed 

 classification is desired, the U.S. Soil Conservation Ser- 

 vice classification system should be used. 



Special Modifiers 



Many wetlands and deepwater habitats are man-made, 

 and natural ones have been modified to some degree by 

 the activities of man or beavers. Since the nature of these 

 modifications often greatly influences the character of 

 such habitats, special modifying terms have been included 

 here to emphasize their importance. The following Mod- 

 ifiers should be used singly or in combination wherever 

 they apply to wetlands and deepwater habitats. 



Excavated 

 Lies within a basin or channel excavated by man. 



Impounded 



Created or modified by a barrier or dam which pur- 

 posefully or unintentionally obstructs the outflow of water. 

 Both man-made dams and beaver dams are included. 



Diked 



Created or modified by a man-made barrier or dike 

 designed to obstruct the inflow of water. 



Partly Drained 



The water level has been artificially lowered, but the 

 area is still classified as wetland because soil moisture is 

 sufficient to support hydrophytes. Drained areas are not 

 considered wetland if they can no longer support 

 hydrophytes. 



Farmed 



The soil surface has been mechanically or physically 

 altered for production of crops, but hydrophytes will 

 become reestablished if farming is discontinued. 



Artificial 



Refers to substrates classified as Rock Bottom, Uncon- 

 solidated Bottom, Rocky Shore, and Unconsolidated Shore 

 that were emplaced by man, using either natural materials 

 such as dredge spoil or synthetic materials such as dis- 

 carded automobiles, tires, or concrete. Jetties and break- 

 waters are examples of Artificial Rocky Shores. Man-made 

 reefs are an example of Artificial Rock Bottoms. 



REGIONALIZATION FOR THE 

 CLASSIFICATION SYSTEM 



In this classification system, a given taxon has no par- 

 ticular regional alliance; its representatives may be found 

 in one or many parts of the United States. However, 

 regional variations in climate, geology, soils, and vegeta- 

 tion are important in the development of different wetland 

 habitats; and management problems often differ greatly 

 in different regions. For these reasons, there is a need 

 to recognize regional differences. Regionalization is 

 designed to facilitate three activities: (1) planning, where 

 it is necessary to study management problems and poten- 

 tial solutions on a regional basis; (2) organization and 

 retrieval of data gathered in a resource inventory; and (3) 

 interpretation of inventory data, including differences in 

 indicator plants and animals among the regions. 



We recommend the classification and map (Fig. 7) of 

 Bailey (1976) to fill the need for regionalization inland. 

 Bailey's classification of ecoregions is hierarchical. The 

 upper four levels are domain (defined as including sub- 

 continental areas of related climates), division (defined as 

 including regional climate at the level of Koppen's [1931] 

 types), province (defined as including broad vegetational 

 types), and section (defined as including climax vegeta- 

 tion at the level of Kuchler's [1964] types). On the map, 

 the boundaries between the different levels are designated 

 by lines of various widths and the sections are numbered 

 with a four-digit code; digits 1 through 4 represent the 

 first four levels in the hierarchy. The reader is referred 

 to Bailey (1976, 1978) for detailed discussion and descrip- 

 tion of the units appearing on his map, reproduced in our 

 Fig. 7. 



The Bailey system terminates at the ocean, whereas the 

 present wetland classification includes Marine and Estu- 

 arine habitats. Many workers have divided Marine and 

 Estuarine realms into series of biogeographic provinces 

 (e.g., U.S. Senate 1970; Ketchum 1972). These provinces 

 differ somewhat in detail, but the broader concepts are 

 similar. Figure 7 shows the distribution of 10 Marine and 

 Estuarine provinces that we offer for North America. 



• Arctic Province extends from the southern tip of New- 

 foundland (Avalon Peninsula), northward around Canada 

 to the west coasts of the Arctic Ocean, Bering Sea, and 

 Baffin and Labrador basins. It is characterized by the 

 southern extension of floating ice, the 4°C summer iso- 

 therm, and Arctic biota. 



• Acadian Province extends along the Northeast Atlan- 

 tic Coast from the Avalon Peninsula to Cape Cod and is 

 characterized by a well developed algal flora and boreal 

 biota. The shoreline is heavily indented and frequently 

 rocky. It has a large tidal range and is strongly influenced 

 by the Labrador Current. 



• Virginian Province extends along the Middle Atlan- 

 tic Coast from Cape Cod to Cape Hatteras. The province 



