Chapter 4 



Classification of Inland Wetlands 



The present report is concerned only with the fresh-water and inland 

 wetlands. The estuarine habitat has been excluded to avoid duplication 

 of coverage with the estuarine survey of the Federal Water Pollution 

 Control Administration (Wastler and de Guerrero 1968). Thus in 

 coastal areas, the wetlands in this report are limited to sites free of 

 tidal influence and where the vegetation is typical of fresh-water en- 

 vironments. 



A wetland is recognized as a site where the water table is near, at, 

 or above the surface of the ground for at least some portion of the 

 year. Areas seasonally flooded, such as river flood plains, therefore, 

 qualify as wetlands. Lakes and ponds are included where they are 

 ecologically related to specific wetland types. 



Marshes, swamps, and bogs constitute the three major types of wet- 

 lands, each of which may exhibit various phases or subtypes. Ecologi- 

 cally, they represent a dynamic set of ecosystems that are constantly 

 undergoing change and that are subjected to a diversity of environ- 

 mental influences, such as fluctuations in water level, sedimentation, 

 erosion, fire, and natural and man-induced eutrophication. Wetland 

 development can produce dramatic changes in site conditions, in 

 which lakes and ponds may be transformed into marshes, swamps, or 

 bogs. For example, bodies of water with shallow margins frequently 

 develop littoral zones of submerged, floating, and emergent aquatic 

 vegetation typical of those found in marshes. These aquatic plants may 



