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

The vascular flora of an old-growth mixed mesophytic forest in southeastern Kentucky

Because the goal of natural areas management is often the preservation of biodiversity, documenting botanical species richness is critically important. We con ducted a series of botanical surveys in Big Everidge Hollow, a 52 ha watershed containing old-growth forest, on the Cumberland Plateau of eastern Kentucky. We contrasted our findings with a floristic survey that included parts of our study area, conducted approximately 20 years prior. Our research, from 1999 through 2001, yielded 263 species from 176 genera and 82 families, including 19 species that were new records from the site. These new species may have been overlooked in the previous study because of their scarcity or highly cryptic taxonomy, or they may have established in the years between studies. Of the 263 species recorded in our surveys, only one is considered non-native. This remarkable absence of exotic species indicates the high levels of ecological integrity inherent the study site and suggests an increasingly vital role for old-growth forests as reference ecosystems

Site Characteristics as Predictors of Lonicera maackii in Second-Growth Forests of Central Kentucky, USA

Non-native invasive plants can negatively affect the abundance and survival of native plant species and alter ecosystem function. Amur honeysuckle (Lonicera maackii) is an invasive shrub that is an increasingly onerous problem for forest managers in eastern North America. We examined site-specific characteristics related to the presence and abundance of Amur honeysuckle, and other non-native invasive plants, in 15 second growth forests in central Kentucky. Individual remnants were characterized by: (1) frequency and cover of non-native invasive and native shrubs, (2) overstory tree basal area, (3) forest floor litter depth, (4) species composition of leaf litter, and (5) soil characteristics. Of the measured variables, the only statistically significant relationships we discovered were between Amur honeysuckle and characteristics of the forest floor. We found significant negative relationships between Amur honeysuckle presence and both forest floor litter depth (P = 0.01) and the percent of oak (Quercus spp.) litter on the forest floor (P = 0.004). The abundance (percent cover) of Amur honeysuckle was significantly and negatively related to forest floor litter depth (P = 0.03). These findings suggest that forest floor mass creates a barrier to invasion by exotic plants and that forests dominated by oak species may be more resistant to invasion by Amur honeysuckle. While this study did not identify a causal relationship between litter depth and oak litter and the presence of Amur honeysuckle, our findings do suggest that older forests, and those dominated by oak, may be more resistant to the invasion of Amur honeysuckle

Site Characteristics as Predictors of Lonicera maackii

Non-native invasive plants can negatively affect the abundance and survival of native plant species and alter ecosystem function. Amur honeysuckle (Lonicera maackii) is an invasive shrub that is an increasingly onerous problem for forest managers in eastern North America. We examined site-specific characteristics related to the presence and abundance of Amur honeysuckle, and other non-native invasive plants, in 15 second growth forests in central Kentucky. Individual remnants were characterized by: (1) frequency and cover of non-native invasive and native shrubs, (2) overstory tree basal area, (3) forest floor litter depth, (4) species composition of leaf litter, and (5) soil characteristics. Of the measured variables, the only statistically significant relationships we discovered were between Amur honeysuckle and characteristics of the forest floor. We found significant negative relationships between Amur honeysuckle presence and both forest floor litter depth (P = 0.01) and the percent of oak (Quercus spp.) litter on the forest floor (P = 0.004). The abundance (percent cover) of Amur honeysuckle was significantly and negatively related to forest floor litter depth (P = 0.03). These findings suggest that forest floor mass creates a barrier to invasion by exotic plants and that forests dominated by oak species may be more resistant to invasion by Amur honeysuckle. While this study did not identify a causal relationship between litter depth and oak litter and the presence of Amur honeysuckle, our findings do suggest that older forests, and those dominated by oak, may be more resistant to the invasion of Amur honeysuckle