26 



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 modifiers 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 

 purposefully 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, 

 Unconsolidated Bottom, Rocky Shore, and Uncon- 

 solidated Shore that were emplaced by man, using 

 either natural materials such as dredge spoil or syn- 

 thetic materials such as discarded automobiles, tires, 

 or concrete. Jetties and breakwaters 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 

 particular regional alliance; its representatives may be 

 found in one or many parts of the United States. 

 However, regional variations in climate, geology, soils, 

 and vegetation 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 dif- 

 ferences. Regionalization is designed to facilitate three 

 activities: (1) planning, where it is necessary to study 

 management problems and potential 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 

 subcontinental 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 vegetation 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 a detailed discussion and description 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 

 estuarine habitats. Many workers have divided marine 

 and estuarine realms into series of biogeographic prov- 

 inces (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 

 Newfoundland (Avalon Peninsula), northward around 

 Canada to the west coasts of the Arctic Ocean, Bering 

 Sea, and Baffin and Labrador basins. It is charac- 

 terized by the southern extension of floating ice, the 

 4°C summer isotherm, and arctic biota. 



• Acadian Province extends along the northeast 

 Atlantic 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 fre- 

 quently rocky. It has a large tidal range and is 

 strongly influenced by the Labrador Current. 



• Virginian Province extends along the middle 

 Atlantic coast from Cape Cod to Cape Hattaras. The 

 province is transitional between the Acadian and Caro- 

 linian provinces (which follow). The biota is primarily 

 temperate, but has some boreal representatives. The 

 Labrador Current occasionally extends down to Cape 

 Hattaras and winter temperatures may approach 4°C. 

 The tidal range is moderate. 



• Carolinian Province is situated along the south 

 Atlantic coast from Cape Hattaras to Cape Kennedy. 

 It contains extensive marshes and well-developed 

 barrier islands. Waters are turbid and productive. The 



