Recovery of forest floor diversity after removal of the nonnative, invasive plant Euonymus fortunei

The vine Euonymus fortunei (Turcz.) Hand.-Mazz. is invading forests of the eastern United States; as a result, removal of E. fortunei has become a priority of resource managers. This study examined the effectiveness of five techniques for eliminating E. fortunei, restoring plant species richness, and enhancing recolonization by woody species. In 2003, the following five treatments were applied: burn with a propane torch, light exclusion by plastic tarp, burn and glyphosate application, cut (simulated grazing) and glyphosate application, mow and glyphosate application, plus an untreated control. Each treatment was replicated four times in a randomized block design located in a heavily E. fortunei-invaded forest remnant in Lexington, KY. Vegetation was surveyed in 2004, 2005, 2006, 2007, and 2013. Across years, most treatments were associated with reduced E. fortunei cover and increased total species richness. Over time, E. fortunei cover increased across treatments, such that by 2013, no difference in E. fortunei cover was detectible among treatments. Some differences in total and native species richness among treatments were still perceptible by 2013. Increased E. fortunei cover was correlated with decreased ground-layer species richness, native species richness, sapling richness, and sapling density. Light exclusion by plastic tarp, a method absent from many management recommendations, was unique in its long-term reduction of E. fortunei cover and its association with increased total species richness, but use of plastic tarps may have drawbacks. This study quantified the long-term community effects of removing an established invasive species from a mature, urban forest. Removal allowed native plants, notably woody species, to reestablish. Because richness continues to decline as E. fortunei reinhabits plots, land managers seeking to conserve biodiversity under conditions similar to those within our study site should maintain proactive E. fortunei removal plans.