In this case study, we evaluated a point-mapping method for simultaneously collecting data while controlling three invasive woody plant species: black locust, Chinese privet, and hardy orange. The study in Arkansas Post National Memorial included seven project areas ranging in size from 2.7 to 27.3 ha and spanned six field seasons (2010 to 2015). The control techniques varied depending on plant size and always included the application of herbicide, which also varied over the course of the study to include glyphosate, imazapyr, and triclopyr. Each person responsible for controlling plants simultaneously collected global positioning system point data to estimate the foliar cover of the plants treated. The resulting data demonstrated evidence of decreases in all three plant species in most project areas during the 6-yr period. Initial increases in area treated for some species–area combinations reflected differences in the preliminary efforts required to control invasive plants in entire project areas, but by 2012 six of seven project areas were treated in their entirety. Despite a high level of reduction, in some cases, the plants persisted at low levels even during the sixth year of the project. Our findings support the ability of this method to granularly detect changes in plant abundance while simultaneously controlling invasive plants. With several acknowledged limitations, this streamlined project-based monitoring approach provides data that allow managers to assess the effectiveness of weed control treatments.

Chinese privet is a major invasive shrub within riparian zones throughout the southeastern United States. We removed privet shrubs from four riparian forests in October 2005 with a Gyrotrac® mulching machine or by hand-felling with chainsaws and machetes to determine how well these treatments controlled privet and how they affected plant community recovery. One year after shrub removal a foliar application of 2% glyphosate was applied to privet remaining in the herbaceous layer. Three “desired-future-condition” plots were also measured to assess how well treatments shifted plant communities toward a desirable outcome. Both methods completely removed privet from the shrub layer without reducing nonprivet shrub cover and diversity below levels on the untreated control plots. Nonprivet plant cover on the mulched plots was > 60% by 2007, similar to the desired-future-condition plots and higher than the hand-felling plots. Both treatments resulted in higher nonprivet plant cover than the untreated controls. Ordination showed that after 2 yr privet removal plots were tightly grouped, suggesting that the two removal techniques resulted in the same plant communities, which were distinctly different from both the untreated controls and the desired-future-condition. Both treatments created open streamside forests usable for recreation and other human activities. However, much longer periods of time or active management of the understory plant communities, or both, will be required to change the forests to typical mature forest plant communities.

Throughout the world, the invasion of nonnative plants is an increasing threat to native biodiversity and ecosystem sustainability. Invasion is especially prevalent in areas affected by land transformation and disturbance. Surface mines are a major land transformation, and thus may promote the establishment and persistence of invasive plant communities. Using the Shale Hills region of Alabama as a case study, we assessed the use of landscape characteristics in predicting the probability of occurrence of six invasive plant species: sericea lespedeza, Japanese honeysuckle, Chinese privet, autumn-olive, royal paulownia, and sawtooth oak. Models were generated for invasive species occurrence using logistic regression and maximum entropy methods. The predicted probabilities of species occurrence were applied to the mined landscape to assess the probable prevalence of each species across the landscape. Japanese honeysuckle had the highest probable prevalence on the landscape (48% of the area), with royal paulownia having the lowest (less than 1%). Overall, 67% of the landscape was predicted to have at least one invasive plant species, with 20% of the landscape predicted to have two or more species, and 3% of the landscape predicted to have three or more species. Japanese honeysuckle, sericea lespedeza, privet, and autumn-olive showed higher occurrence on the reclaimed sites than across the broader region. We found that geospatial modeling of these invasive plants at this scale offered potential for management, both for identifying habitat types at risk and areas that need management attention. However, the most immediate action for reducing the prevalence of invasive plants on reclaimed mines is to remove invasive plants from the reclamation planting list. Three (sericea lespedeza, autumn-olive, and sawtooth oak) out of the six most common invasive plants in this study were planted as part of reclamation activities.

The identification of privet in the middle southern United States can be difficult. Because most introduced species of privet can be invasive, and recent mapping projects seek location and species population data, proper identification is important. Without proper identification of privet species, data on species distributions and other pertinent information regarding invasiveness could lead to improper conclusions. Currently, information on privet identification is scattered throughout a number of reference materials. The purpose of this publication is to assist with the proper identification of escaped privet species, and suggest management options.

As invasive species become increasingly abundant in forests, their presence may influence a number of key nutrient cycling processes. For example, Chinese privet has become well established in southeastern forests and continues to spread. Two studies, a multisite field investigation and a controlled approach on a single site, were conducted to examine the role of Chinese privet (Ligustrum sinense) on decomposition within riparian forests of the Georgia Piedmont. The field study also investigated the effects of privet presence on soil nitrogen (N) mineralization and microbial carbon and N immobilization. Both studies utilized a litterbag approach to examine how increasing proportions of privet in foliar litter influenced mass loss rates and nutrient dynamics. The field investigation included litterbags with representative proportions of the five dominant species from 16 sites. Litterbags in the controlled study were composed of specific levels of privet litter within bags (0, 10, 20, 30, 40, and 50% Chinese privet) as treatments. The litter quality of four native species was compared to Chinese privet in the controlled study. Both studies showed significant positive relationships between percentage of Chinese privet in litterbags and decomposition rates (2.6-fold rate increase with 30% privet in litterfall). Chinese privet leaf litter had lower lignin and cellulose concentrations, higher N concentrations, lower lignin : N ratios, and narrower C : N ratios than the native species. The positive relationship between mass loss rates and the proportion of Chinese privet in litter indicates that Chinese privet enhances decomposition rates as it becomes more abundant. During summer, N mineralization showed approximately a fivefold increase; during winter, microbial biomass N increased by approximately 30% on sites with the highest levels of privet in the understory. Consequently, C and N dynamics in Piedmont riparian forests were significantly influenced in direct proportion to the amount of privet present in the understory.

There is a limited understanding about the ecological mechanisms that enable certain plant species to become successful invaders of natural areas. This study was conducted to determine the soil and landscape characteristics that correlate with invasion of Chinese privet (CHP), and to develop a model to predict the probability of CHP invasion in Piedmont forests. A landscape ecosystem classification (LEC) system—based on the percentage of clay in the B horizon, depth to maximum clay (cm), exposure, terrain shape, and aspect (degrees)—was used to determine the soil moisture characteristics of invaded and uninvaded plots. Additional measurements included the cover classes of CHP and other species, litter depth (cm), slope (degrees), overstory basal area (m2 ha−1), and soil chemical properties. CHP invasion was negatively correlated with overstory basal area and slope and positively with litter depth and pH. A stepwise logistic regression model containing these four variables was highly sensitive, with an overall accuracy of 78%. Given the accuracy of this model, we propose that it can be used to calculate the probability of invasion in a given area, provided that some basic, readily obtainable site characteristics are known.