Geospatial Assessment of Invasive Plants on Reclaimed Mines in Alabama

Abstract 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. Nomenclature: Autumn-olive, Elaeagnus umbellata Thunb. , Chinese privet, Ligustrum sinense Lour. , Japanese honeysuckle, Lonicera japonica Thunb. , royal paulownia, Paulownia tomentosa (Thunb.) Sieb. & Zucc. ex Steud. , sawtooth oak, Quercus acutissima Carruthers, sericea lespedeza, Lespedeza cuneata (Dumont) G. Don Management Implications: Geospatial modeling of the invasive plants studied, at this project scale, is useful and offers the potential for management both in terms of identifying habitat types most at risk and identifying areas that need management attention. At an individual species level we did not determine the need for strong active management for Japanese honeysuckle (ubiquitous), or royal paulownia (very low prevalence), both volunteer species. The only species not planted for which we suggest active management is Chinese privet. This species is considered to be the second most abundant invasive plant in the South and possibly the most detrimental. We would suggest that privet is of management concern in the Shale Hills region (SHR) given its potential distribution, and that as forest regenerates that it would be advisable to manage for privet, particularly in the depressions and low-lying areas that are more hydric and closer to water. The most immediate action for reducing the prevalence of invasive plants on reclaimed mines would be to remove invasive plants from the reclamation planting list. Three out of the six most common invasive plants have been planted as part of reclamation activities. For the planted species, sericea lespedeza was the most prevalent; however, it may be competitively excluded as forest reestablishes. For the management of this species, increased canopy cover with a diverse forest structure seems to be the best long-term approach, but the best management practice to assist in eliminating this species from the reclaimed sites would be to remove it from allowable seeding mixtures. Autumn-olive, also planted, is not at high densities throughout the larger region; it is very likely that removal of current infestation and no future planting activity would be very worthwhile and possible lead to eradication in the SHR.