Often called the "kidneys" of the environment, wetlands act as buffer zones between land and waterways. In addition to absorbing carbon and holding onto it for years a process called sequestration wetlands filter out chemicals in water that runs off from farm fields, roads, parking lots and other surfaces.
When the two experimental wetlands were created in 1994, researchers planted 13 common wetland species in one marsh and left the other to develop as a natural wetland. Water from the nearby Olentangy River has been continually pumped into both marshes at rates to mimic water flow in a freshwater river wetland setting.
Within five years, both wetlands contained almost 100 different species each, and that plant diversity was maintained through the study period's end in 2008.
"I was surprised that the vegetation, the types of species and diversity of the plants, jumped up very fast, by year five," Mitsch said. By 1998, the planted wetland hosted 96 species and the naturally developing marsh was home to 87 species. Those numbers increased to 101 and 97 species, respectively, by 2008.
Seven dominant plant types were growing in year 15 in the created wetland: bur-reed, a variety of cattails, river bulrush and softstem bulrush, American lotus, sago pondweed and rice cutgrass. The three dominant plant types in the natural wetland at year 15 were the rice cutgrass, softstem bulrush and cattails.
"The naturally developing wetland was more powerful, the planted wetland still slightly more diverse," Mitsch said.
Even with that growth, Mitsch calls the wetlands "unfinished." He and his colleagues expect these two experimental marshes to be followed for a total of at least 50 years by university scientists of the future to tell the whole story of the similarities and differences between man-made and natural wetlands.
"I foresee that they will become more and more tre
|Contact: William Mitsch|
Ohio State University