Anoka Ecosystems:
Mixed Emergent Marsh
Mixed emergent marshes are a broad category of marsh ecosystems which have a heterogeneous species composition and occur on flooded soils with wetland vegetation. These ecosystems typically occur in semipermanently flooded areas, such as river backwaters, the edges of ponds and lakes, or the deepest areas of shallow wetland basins. These marshes are similar to cattail marshes, though forbs common in cattail marshes are less likely to colonize and the river and lake bottoms of cattail marshes are generally softer and muckier. However, given that this is such a broad category of marshes, there are few other all-encompassing qualities of this ecosystem, and it is likely that further definition and resulting division of subtypes will occur.
Unlike cattail marshes, in mixed emergent marshes, cattails, shrubs and trees are NOT the dominant vegetation. Vegetation is often very diverse and includes many different rushes, common reed grass, prairie cordgrass, broad-leaved arrowhead and others. In addition to these species, mixed emergent marshes often have plants which are highly resilliant and can survive flooding and other harsh conditions as seeds, tubers, rhizome fragments, and dormant parts of the plant. Opportunistic species, such as monkey-flower, spike rushes, umbrella sedges, and others germinate quickly on exposed or eroded soils.
This community is very susceptable to damage via fertilizer runoff or drainage. Due to its relation to the upland ecosystems surrounding it, a mixed emergent marsh can be fundamentally changed by a change in nutrient availability. If disturbed, the community is very susceptible to invasives and other opportunistic species, such as reed canary grass, or may evolve into an unnatural cattail marsh.
Sources:
"Minnesota Land Cover Classification System: User Manual." Version 5.3 Minnesota Department of Natural Resources, Central Region, 2004.
"Minnesota's Native Vegetation: A Key to Natural Communities" Version 1.5 Minnesota Department of Natural Resources, Natural Heritage Program, 1993.
Wovcha, D, Delaney, B, Nordquist, G. Minnesota's St. Croix River Valley and Anoka Sandplain: A Guide to Native Habitats Minneapolis: University of Minnesota, 1995.
