In Review, Environmental Monitoring and Assessment

Wetland biomonitoring approaches are needed to determine when changes in response to stressors are occurring and to predict the consequences of proposed land use changes. These approaches require an understanding of shifts in biota that occur in response to land use; data that is lacking for most kinds of wetlands. Changes in floristic composition corresponding to land use differences at multiple scales (site to 2500 m radius) were characterized for forty wet meadows associated with prairie glacial marshes in Minnesota (USA). Site impacts (stormwater, cultivation) and landscape disturbance (agriculture and urbanization, combined), coincide with a reduction in native graminoid and herbaceous perennial abundance (e.g., Carex lasiocarpa, Calamagrostis canadensis, Spartina pectinata). This vegetation is replaced with annuals (e.g, Bidens cernua, Polygonum pensylvanicum) in recently cultivated sites or introduced perennials (e.g., Phalaris arundinacea, Typha angustifolia) and floating aquatics (lemnids) in stormwater impacted wetlands. Ditches also reduce native perennial importance and increase perennials, but only when they are in highly impacted landscapes.

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