Plant diversity and composition in the absence of the exotic invasive, Microstegium vimineum, at a wetland restoration site in Raleigh, North Carolina

The breakdown of global barriers has accelerated introductions of exotic species into new environments.  The large ecosystem disturbance caused when restoring wetlands provides an excellent template for invasive species to establish and flourish.  This is the case at the Yates Millpond wetland restoration site in Raleigh, North Carolina.  Yates Millpond had little of the exotic, invasive species Microstegium vimineum before restoration construction, yet contained a near monoculture of the species after restoration construction was complete in 2002.  In 2005, a M. vimineum removal experiment was initiated to determine the plant community that is suppressed by M. vimineum presence.  Treatments consist of 6 light and 6 shade plots.  Within each plot, two 2.25m² quadrats were established for a split plot treatment of M. vimineum removal versus an unweeded control.  M. vimineum was continuously removed throughout the growing seasons of 2005 and 2006 and the percent cover of all subsequent vegetation was recorded.  After one growing season (2005), the results of removing M. vimineum were dramatic.  The light plots without M. vimineum had more than double the average number of species and Shannon diversity as well as much higher evenness than plots with M. vimineum.  The shade plots without M. vimineum also showed higher species richness, Shannon diversity and evenness than with M. vimineum.  These results show the ability of M. vimineum to dominate a plant community and have implications for vegetation recovery with the removal of an exotic.