While several exotic grass species have been identified as "highly invasive" when introduced to North American grasslands, tall fescue (Festuca arundinacea, syn. Lolium arundinaceum) has apparently received relatively little attention from either researchers or managers. Tall fescue is the most abundant grass in the Eastern United States, and is frequently associated with an endophytic fungus. The fungal endophyte produces an alkaloid toxic to grazing mammals. Recent research, however, has revealed that the endophyte is capable of altering ecological relationships in native grassland, and has been experimentally shown to confer drought tolerance on the host plant, alter soil microbe communities, reduce native plant cover, and reduce litter. Given the potential for tall fescue to alter community composition and fire regimes as an invader in remnant grassland, current ecological theory regarding grass invasion and its effects on fire frequency is lacking for this species. The dominant models for grass invasions pertain to annual grasses, e.g. cheatgrass (Bromus tectorum), in Western North American ecosystems that shorten fire-return interval.

Results/Conclusions

This paper proposes a general conceptual model for predicting and describing the effects of invasive species on the fire regime of native communities. Our model focuses on the effects of exotic species invasion on fire regime, specifically in terms of modification of fuel bad characteristics that either promote or inhibit fire frequency.

Additionally, our model takes into account the effects of anthropogenic promotion, herbivory, and feedback loops on fire regime change. By taking into account these effects, our model provides a more robust manner of assessing the potential for ecosystem-level changes, such as alteration of fire regime, by invasive species. This predictive quality aids in determining management priorities in terms of invasive species control.