A clear and widely accepted definition of a wetland has yet to be established. Wetlands are of various types and function, and occur in diverse locations, and climates which in part make them difficult to define. Many definitions of a wetland have been posed by different groups and individuals, some of the definitions include: “An area of land that has hydric soil and hydrophytic vegetation, typically flooded for part of the year, and forming a transition zone between aquatic and terrestrial systems (Brady and Weil, 1999).” A wetland is an ecosystem that depends on constant or recurrent, shallow inundation or saturation at or near the surface of the substrate (soil). The minimum essential characteristics of a wetland are recurrent, sustained inundation or saturation at or near the surface and the presence of physical, chemical, and biological features reflective of recurrent, sustained inundation or saturation. (National Research Council, 1995).” In general Mitsh and Gosselink (1993) define wetlands as areas that have characteristics of both aquatic and terrestrial ecosystems, but are neither.
Wetland classification systems are not used consistently by all groups of people, consequently wetland classification differences occur regionally. Wetlands classifications include; bogs, fens, swamps and flood plain forests, marshes, and wet meadows. In North Carolina Wetlands are classified by the source of moisture and include; wetlands sustained by rainfall, wetlands sustained by ground water discharge, wetlands sustained by ground water and surface water, wetlands on rivers and lakes, and wetlands on the ocean. This classification system has subcategories under each type of wetland (Vepraskas, 2000). A good overview of the classification system for wetlands used in North Carolina can be found in “A Field Guide to North Carolina Wetlands” printed in 1996, by EPA #904/B-94/001, DEM Report NO. 96-01, NCDENR, Div. of Envir. Mngt. Water quality section.
Wetlands are defined for classification purposes as areas that under natural conditions posses three factors including: hydric soil, wetland hydrogeology, and hydrophytic vegetation. Hydric soils are soils that are anaerobic (without oxygen gas) for at least one week during the growing season (Lilly, 1993). Specific criteria to identify hydric soils are not easy to develop, but indicators have been developed by scientist to aid in their delineation. Hydric soil indicators are listed in “Field Indicators of Hydric Soils in the United States: A guide for identifying and delineating hydric soils” which was printed by the United States Department of Agriculture in March of 1993. A publication written by Vepraskas in 1993 entitled “Redoximorphic Features for Identifying Aquic Conditions” is also available through the North Carolina Cooperative Extension Service. Wetland hydrology criteria are based on depth of the water table from the soil surface and the...