Susceptibility of a tallgrass prairie to invasion by the herbicidal producing species, Festuca rubra

Disturbance, nutrients, propagule pressure, and the presence of arbuscular mycorrhizal fungi (AMF) have been shown to influence invasion in plant communities, although the relative importance of each remains unclear. A remnant of tallgrass prairie outside Cambridge, ON appears to be resilient to invasion by Festuca rubra, despite its herbicidal properties. A greenhouse experiment was conducted to determine what factors are responsible for the resilience of the native grassland, using synthesized fescue and native sod. The effects of disturbance, nutrient enrichment, propagule pressure, and the presence of AMF and phytotoxin on the establishment ability of F. rubra and the native species Sorghastrum nutans were examined. Propagule pressure was the only factor shown to influence fescue invasion and establishment of S. nutans was unaffected by all factors. These results suggest that the resilience of the native grassland may be due to decreased seed production or viability of F. rubra and not any characteristics of the grassland. Also, the restoration of native grasslands will not be limited by remnants of phytotoxin in the soil, following removal of exotic species.