ABSTRACT
Most landscapes contain wetland ecosystems that form transitions (ecotones) between upland and open water ecosystems. In the U.S., the Clean Water Act regulates wetlands in order to maintain wetland functions (e.g., flood protection and water quality improvement). Theoretically, wetland areas that carry out these functions are delineated for regulatory jurisdiction. Ideally, the boundary would be drawn at the point where critical functions diminish rapidly as one moves from the wetter to the drier parts of the ecosystem. Because scientific data on functional capacity are difficult to obtain, structural attributes which can be examined over shorter periods of time often are used as surrogate measures. Species composition, soil type, and hydrologic indicators all have proven to be useful indicators of wetland functioning. Thus, in delineating wetlands for any purpose, it must be remembered that wetland functions are a product of all components of the wetland ecosystem (not just vascular plants), that the wetland functions year round (not just when vascular plants are actively growing), and that critical functions (such as flood protection) will occur only at irregular intervals.
In a landscape context, wetlands and wetland ecotones are important transition zones between uplands and aquatic ecosystems. They are sites where nutrient concentrations change as water flows between terrestrial and aquatic ecosystems, and are thus important buffers between uplands and open waters. Research questions are suggested in two categories: (1) issues related to planning for maintenance of wetland functions, and (2) issues specifically related to effective wetland management.
