Is Invasive Species Control the Goal or Just the First Step in Restoration of the Native Plant Community? Mexican Petunia (Ruellia simplex) Invaded-Forest Floodplains As a Case Study

Invasive species have detrimental ecosystem impacts in that they reduce biodiversity and alter ecosystem function. They also have considerable economic impacts. While the scale of the problem is well-documented, there is less research concerning applied invasive plant control. This is problematic for managers who need to not only reduce invasive species, but also establish an appropriate native community in their place. Though active revegetation is widely attempted in restoration, these efforts are rarely incorporated into invasive species control plans. Revegetation may be beneficial for both establishing native species and for controlling future invasions. Planting native species may be particularly important to managing ornamental invasive plant species, because repeated re-introductions are typical, particularly if home landscapes neighbor natural areas. Primary unanswered questions associated with the effectiveness of revegetation efforts include: 1) under which circumstances is revegetation necessary?, 2) what species and plant material sources are appropriate?, and 3) what follow up treatments may be needed after planting? We have investigated restoration of Mexican petunia (Ruellia simplex)-dominated floodplain wetlands to explore control methods and revegetation techniques. This species is highly used in landscapes and popular among producers and consumers for its yearlong flowering, ease of propagation, and use under many landscape conditions. Studies reveal that while herbicide treatments effectively control Mexican petunia in the short-term, the return of native species does not follow naturally despite an intact and diverse seedbank. Preliminary experiments with revegetation techniques suggest that planting quick-to-establish native species suppresses Mexican petunia reinvasions and facilitates restoration.  We offer our experimental approach as a model system to explore restoration of ornamental-invaded ecosystems, and highlight the important contribution of horticultural knowledge to the field of ecosystem restoration.