HYDROGEOCHEMICAL INVESTIGATION OF NATIVE WILD RICE HABITAT IN SOUTHWEST MICHIGAN

The Hultmark Preserve, a wetland protected by the Southwest Michigan Land Conservancy in Van Buren County, Michigan, is a unique geomorphic location that provides habitat for Great Lakes native wild rice (Zizania aquatica) and other native vegetation. This site provides a setting to evaluate the hydrogeochemical condition of a relatively pristine ecosystem where this endangered species is present. Because wild rice is an economic resource and has deep spiritual ties to Native American tribes such as the Ojibwe, Lakota, Potawatomi, Menomonie, and the Ho Chunk, there is significant interest in understanding geochemical parameters that provide vital conditions needed for the survival of native habitats. This study sought to characterize the hydrogeochemistry of the wetland system housing these native species. An initial site delineation was constructed which included the construction of maps and an overall evaluation of the wetland’s geomorphology that included evaluation of lithology and organic matter from sediment cores. Evaluation of sediment cores revealed high organic matter content which is believed to be influencing the biogeochemical condition. Hydrogeochemical characterization of the wetland system included regular monitoring of surface water and porewater geochemical parameters such as pH, conductivity, redox potential, dissolved oxygen, and major ions. A combination of drive point wells and piezometers were used to collect porewater samples from the root zone and routinely monitor water level and pressure head. Results indicate the wetland is overall anoxic and dominantly sulfate-reducing. These parameters were also used to determine recharge source, either groundwater-fed or precipitation-fed. These results indicate the importance of evaluating environments housing native species to provide a guide for long-term monitoring, protection, rehabilitation, and preservation of such habitats for future generations.