Freshwater wetlands can mean many different things. To some, the vitality and beauty of marshes can only be described and captured in words and pictures. At the opposing extreme, urban engneers and planners see wetlands as unused space that can be exploited for drainage or as the possible receptacle of human waste products. To the ecologist, freshwater wetlands are complex systems.  To past farmers and countryfolk they have generally represented an extremely important renewable resource.  This view is returning as culivation of crops for the mass production of energy becomes profitable.

Ecological definitions vary markedly from marshes of glacial origin, to prairie wetlands, to freshwater marshes of estuarine areas that experience severe fluctuations in water movement under tidal influences. In glaciated regions, marshes are often remnant wetlands of shallow lake systems in which vegetation extends over the entire water surface. Technically a swamp or bog contains persistent standing water among the vegetation, whereas marshes contain water-saturated sediments with no or little standing water among the vegetation. The conditions of wetlands change markedly and rapidly in response to fluctuations in climate and rainfall. Many of these responses are cyclical with long-term periods.

All of these defining features of freshwater wetlands makes them good educational models for understanding the inerplay between culture and ecology, where the emphasis is on managing systems of

biological productivity in relation to water and nutrient flows.