Can an invasive species alter the hydrologic regime of a wet prairie?

English Abstract:

The hydrologic characteristics of the Oak Openings Region in Northwest Ohio, USA, a globally rare ecosystem, are not well understood. It originally consisted of oak savannas, wet prairies, oak woodlands, oak barrens, and floodplain forests. Currently, the Oak Openings supports globally rare oak savanna and wet prairie habitats. The wet prairies in the region have been drained by ditches and encroached by invasive plants (mainly glossy buckthorn - Rhamnus frangula), which have altered the natural flow making it an unusually variable and artificial system. Groundwater and ditch levels were monitored at six wet prairie restoration sites during three years. Each site consisted of a clustered set of five piezometers positioned on a transect perpendicular to the main ditch. Within each ditch reach, a surface water monitoring location was also set. Of the six sites, two were set as control sites, where the glossy buckthorn was not removed for a period of time. Results show a different response in the groundwater level of the control sites, but only under certain hydrologic conditions. The longer growing season of the buckthorn depressed groundwater levels until the beginning of November during dry years, though not under wet or normal years.