Hydrogeomorphic factors and ecosystem responses in coastal wetlands of theGreat Lakes

Gauging the impact of manipulative activities, such as rehabilitation or ma nagement, on wetlands requires having a notion of the unmanipulated conditi on as a reference. An understanding of the reference condition requires kno wledge of dominant factors influencing ecosystem processes and biological c ommunities. In this paper, we focus on natural physical factors (conditions and processes) that drive coastal wetland ecosystems of the Laurentian Gre at Lakes. Great Lakes coastal wetlands develop under conditions of large-la ke hydrology and disturbance imposed at a hierarchy of spatial and temporal scales and contain biotic communities adapted to unstable and unpredictabl e conditions. Coastal wetlands are configured along a continuum of hydrogeo morphic types: open coastal wetlands, drowned river mouth and flooded delta wetlands, and protected wetlands, each developing distinct ecosystem prope rties and biotic communities. Hydrogeomorphic factors associated with the l ake and watershed operate at a hierarchy of scales: a) local and short-term (seiches and ice action), b) watershed / lakewide / annual (seasonal water - level change), and c) larger or year-to-year and longer (regional and/or greater than one-year). Other physical factors include the unique water qua lity features of each lake. The aim of this paper is to provide scientists and managers with a framework for considering regional and site-specific ge omorphometry and a hierarchy of physical processes in planning management a nd conservation projects.