Assessing the Ecological Condition of Wetlands in the Lower Missouri River Floodplain

Abstract

Changes to the hydrology of the Missouri River and its associated floodplain have dramatically reduced historic flooding cycles, thereby reducing wetland area as well as the ecological integrity of remaining wetlands. This study assesses the ecological condition of wetlands within the Lower Missouri River estimated 500-year floodplain (from Sioux City to St. Louis). The sample population comprises 17 wetlands sampled as part of a "reference" study done in 2005 and an additional 42 wetlands sampled randomly in 2008 and 2009. Wetlands were classified, assessed for disturbance and sampled for a suite of floristic and water quality variables. High conductivity was associated with degraded floristic quality in all wetlands (within regional groups), whereas total nutrient ratios (TN:TP) appeared to have class-specific impacts. Total phosphorous, pH, floristic richness and mean conservatism also grouped by region. However, most water quality variables were found to vary significantly within individual wetlands and by wetland classes. Findings suggest that alterations to structural factors or morphological attributes within wetlands may have more significant impacts on wetland condition than surrounding disturbance or regional trends in disturbance.