Wetland Definitions





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Created by:

Abby Rokosch
Jessen Book
Siobhan Fennessy

Over the past 100 years wetlands have undergone a genesis of definition. In the early years of definition, wetlands were referred to as:

...lowlands covered with shallow and sometimes temporary or intermittent waters. They are referred to by such names as marshes, swamps, bogs, wet meadows, potholes, sloughs, and river overflow lands. Shallow lakes and ponds, usually with emergent vegetation as a conspicuous feature, are included in the definition, but the permanent waters of steams, reservoirs, and deep lakes are not included. Neither are water areas that are so temporary as to have little or no effect on the development of moist-soil vegetation. (Shaw and Fredine, 1956 in Kent, 1994)

This definition was meant primarily for the lay-public and did not define wetlands in scientific terms. Consequently, much revision has been worked into the definition in the nearly half century since the above definition was coined. The current definition comes with the passing of the Clean Water Act, and is used by ecologists, scientists, and landscape engineers to define the land under question.

The term "wetlands" means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. (Kent, 1994)

Whereas Shaw and Fredine (1956) attempted to classify wetlands by using common names, the current—government approved—definition attempts to describe the land and water features of a wetland. Thus, common names are less important, and definitions can be made more accurately based on the biophysical features of the area. While using definitions is helpful to understand how to classify areas of the earth, they by no means encompass all of the functions of a wetland.

Taking the definition one step further, Brinson and Rheinhardt (1994) include in the definition a sense of what the four major operational components of a wetland are: hydrology, biogeochemistry, support of a specific plant community, and support of a specific animal community. A true, functional wetland will meet criteria from each category. Whigham (1999) continues the delineation by citing 11 ecological functions characteristic of a wetland: maintaining static surface water storage; maintaining dynamic surface water storage; retaining particulates; maintaining elemental cycling; removal of imported elements and compounds; maintaining characteristic plant communities; maintaining habitat structure within the wetland; maintaining food webs within the wetland, maintaining habitat interspersion and connectivity among wetlands; maintaining taxa richness of invertebrates; and maintaining distribution and abundance of invertebrates. However, as definitions get more and more complex, Richardson stresses that no one yet can fully understand or appreciate all that wetlands do for the ecosystem/landscape, nor can any one definition encompass all of these functions or ideas (in Young, 1996).