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For information on Wisconsin's natural communities, contact:
Ryan O'Connor
Natural Heritage Inventory Ecologist

Wetland communities of Wisconsin

Key to Wetland Communities of Wisconsin

General Overview

Wetland communities have a common characteristic - their soil, or other substrate, is periodically saturated with or covered by water. A wetland is defined in the Wisconsin Statutes as "an area where water is at, near, or above the land surface long enough to be capable of supporting aquatic or hydrophytic vegetation and which has soils indicative of wet conditions."

Wetlands form where the shape of the land is conducive to retaining water, including flat areas or depressions with limited outflow, where groundwater is present at the land surface and in floodplains with water flow-through. Wetlands can sometimes form in unlikely places, such as on slopes, when the local climate produces continually wet conditions (Verry 1988). Landscape features and other variables that vary from site-to-site will influence both ecological function and plant and animal diversity.

Wetlands are part of the water cycle of all ecosystems, and their location in the landscape allows them to function as a buffer between upland areas and surface waters (Weller 1981). Wetlands perform a number of natural functions that benefit natural ecosystems and society. Water quality is often dependent upon wetlands because they serve to trap sediment, remove nutrients, protect shorelines and slow the effects of flood water. They also serve as both discharge and recharge areas for groundwater and provide habitat for many species of plants and animals (Stearns 1978). In part due to these functions, wetlands exhibit higher biological productivity than most other community types, and support rare biota. Currently, 43% of all federally-listed threatened and endangered species use wetlands at some point in their life cycles (Feierabend 1992). In Wisconsin, 32% of the state's listed species are wetland dependent. Further loss or degradation of wetlands would affect a disproportionate share of Wisconsin's rare species.

At present, Wisconsin has lost 47% of its original ten million acres of wetlands. Many of the remaining 5.3 million acres are in the northern third of the state (Wisconsin DNR 1990). In some southern Wisconsin counties, the amount of wetland loss is well over 75%. Wisconsin's losses are reflective of the national status of wetlands; it is estimated that one-half of the nation's original 221 million acres of wetlands have been lost (Feierabend 1992). A large amount of remaining acreage in Wisconsin exists in a partly altered state, such as with old drainage ditches still functional enough to change the hydrology of the wetland. Much of this remaining wetland acreage was at one time disturbed, either by drainage (followed by restoration) or by being cleared, repeatedly burned, grazed or periodically plowed (Curtis 1959). Disturbance and other factors have opened many wetlands to invasion by non-native invasive species that can reduce the ecological value of wetlands.

Last revised: Wednesday, June 16, 2021