Impacts of an invasive grass Microstegium vimineum (Trin.) A. Camus on growth and survival of the native herb, Impatiens capensis Meerb.

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Usha Upreti (Creator)
Western Carolina University (WCU )
Web Site:
Beverly Collins

Abstract: Microstegium vimineum (Trin.) A. Camus is an invasive annual grass in the eastern United States. It can form dense monocultures along roads and forest understories, displacing native species due to its superior ability to compete for light and soil resources or indirect effects on the soil ecosystem. Impatiens capensis Meerb. is a native annual herb that grows in ditches, along creeks, and along road sides. Microstegium and Impatiens are annuals and can co-occur. Competition between Microstegium and Impatiens was examined in the field in two locations: Kentucky and North Carolina. A total of 180 plots (25cm×25cm) were established in populations where each species was growing by itself (single species plots) or growing together (mixed species plots). Microstegium density and stem mass were compared between the single-species and mixed-species plots in both locations. Impatiens height (cm), stem mass (g), number of fruits, and fruit mass (g) were compared between plot types and locations. I hypothesized that the invasive species would be the stronger competitor and would outcompete Impatiens by lowering its growth and survival. In addition, I compared soil carbon, nitrogen and C: N ratios from the single species and mixed species plots to examine potential indirect effects of Microstegium on the soil ecosystem. In contrast to my hypothesis, the native Impatiens outcompeted invasive Microstegium by reducing its growth and survival. Both mass and density of Microstegium were lower in plots where they grew with Impatiens than in plots where they grew alone. In addition, Impatiens plants were taller and had greater stem mass in mixed plots with Microstegium. Further, number of fruits and fruit mass of Impatiens did not differ significantly when plants were growing with Microstegium. There was no evidence of soil mediated indirect effects of either species. Soil carbon was higher in Kentucky. However, soil nitrogen and carbon did not differ between plot types in either Kentucky or North Carolina, suggesting the observed growth differences of Microstegium and Impatiens between plot types was not due to effects of these species on the soil ecosystem. The results of this study suggest that the invasive grass Microstegium vimineum has no negative impacts on growth and survival of the native herb Impatiens capensis.

Additional Information

Language: English
Date: 2015
invasive plants, native plants
Plant competition -- Kentucky
Plant competition -- North Carolina
Invasive plants -- Kentucky
Invasive plants -- North Carolina
Impatiens -- Kentucky
Impatiens -- North Carolina

Email this document to