Georgia Invasives Case Study
Invasive species are a concern all over the U.S. and all over the world. Some invasive species are well known such as Lionfish or Kudzu in parts of the U.S. However, there are a multitude of other invasive species that can be just as harmful to the surrounding ecosystem, even if they aren’t well known. It’s important to raise awareness of invasive species to help prevent their spread to new areas. This post covers three invasive species that can be found in the state of Georgia.
NOTE: All three species presented below have been identified in some quantity in Lullwater Preserve at Emory University.
Chinese Lespedeza (Lespedeza cuneata)
Lespedeza cuneata is a notoriously invasive perennial on the east coast of the United States, most often found in old fields or prairies (Schutzenhofer et al. 2009). The species was introduced from Asia deliberately in 1895 for use in erosion control and as a forage plant for wildlife (Schutzenhofer et al. 2009). The species became further widespread with the passing of the Surface Mining Control and Reclamation Act in 1977, which listed L. cuneata as one of the acceptable ground cover species for reclamation of old mining sites (Bauman et al. 2015). Old mining sites are often unproductive landscapes and provide more value in spreading invasives than for colonizing native species (Bauman et al. 2015).
L. cuneata is a successful invader of a range of habitat types due to several characteristics that increase the tolerance of the species. The species has a high seed production rate and high dispersal potential, increasing in abundance more than 20 fold in a single year(Schutzenhofer et al. 2009, Kibis and Buyuktahtakin 2017).Another feature of its survival is the large seed bank created, in which seeds can survive for decades (Kibis and Buyuktahtakin 2017). Plants also have a heteromorphic flowering system, producing flowers that can reproduce asexually in addition to flowers that are insect pollinated, which helps to increase the chances of successful reproduction (Schutzenhofer et al. 2009). L. cuneataalso engages in several behaviors that promote its survival over similar native species, such as L. virgnica: these include, shading of other vegetation, allelopathy, resistance to herbivory, and a greater efficiency of light harvesting (Allred et al. 2010).
Approaches to management of L. cuneatadepend on a variety of factors, but in most cases, it is preferable to apply treatment within the first two years of establishment to prevent the building up a sizeable seed bank (Kibis and Buyuktahtakin 2017). The species is most vulnerable in the early stages of its life, but has low rates of natural herbivory in the wild and thrives in disturbed habitats, which makes management strategies such as plowing not useful (Schutzenhofer et al. 2009, Bauman et al. 2015). The most successful treatments are ones involving herbicide and frequent monitoring (Bauman et al. 2015).
Alligator Weed (Alternanthera philoxeroides)
Aternanthera philoxeroidesis a perennial, clonal plant originally from South America that has spread as an invasive species across multiple countries, in both aquatic and terrestrial ecosystems (Wu et al. 2017b). Since it is so widespread, little is known about the exact time and origin of the species within the United States. The species can effectively spread from aquatic systems to terrestrial systems, which may have played a role in its introduction (Wu et al. 2017a).
A. philoxeroidesis a major threat to a number of ecosystems, especially rivers, waterways, wetlands and a number of crops ecosystems, in which it has been linked to declines in crop yields (Tanveer et al. 2018). The species is fast growing, doubling its growth in less than two months and forming dense masses of underground root systems (Tanveer et al. 2018). Aquatic systems are more vulnerable to invasion by A. philoxeroides,but climate change is likely to increase the spread of the species onto land and to higher latitudes (Wu et al. 2017a, Wu et al. 2017b). The species reproduces vegetatively with efficient dispersal via stem fragmentation, and its high genetic variability allows it to occupy a number of niches enhancing its survival (Tanveer et al. 2018).A. philoxeroides inhibits other species through allelopathy and a greater ability to photosynthesize and capture water (Wu et al. 2017b, Tanveer et al. 2018). Its clonal integration also increases its competitive ability against natives and other species present in the habitat (You et al. 2016).
Management practices of this species are numerous, widespread and costly. China alone spends $72 million per year to manage its spread (Tanveer et al. 2018). Practices include physical removal, such as excavating roots, chemical management through herbicide use over a number of years, and biological control(Tanveer et al. 2018). The beetle, Agasicles hygrophila, has been shown to be successful in managing A. philoxeroidesand is used as a management practice in many countries (Tanveer et al. 2018).
Common Periwinkle (Vinca minor)
Vinca minor is an evergreen vine originating from parts of Eurasia (Schulz and Thelen 2000). It is an edge forest species that was commonly used as a decorative plant (Panasenko and Anishchenko 2018). This particular type of periwinkle was introduced at the end of the 19thcentury, especially for its use as ground cover and an edge species in parks and other green spaces(Panasenko and Anishchenko 2018).
V. minor spreads prolifically through vegetative propagation and can form extensive curtains of vines when not controlled (Panasenko and Anishchenko 2018). The species thrives best in forest ecosystems such as pine forests, where it has been shown to greatly reduce forest biodiversity (Panasenko and Anishchenko 2018). Unlike other plants, V. minor grows well in shady regions helping to increase its spread into established forest ecosystems (Tatina 2015). It has been shown to exhibit high allelopathy to the point of inhibiting seed germination of neighboring species, which has greatly aided its survival in otherwise highly diverse forest ecosystems (Panasenko and Anishchenko 2018).
As a relatively new invasive species that has yet to cause the widespread removal efforts of more imposing species such as lespedeza and alligator weed, there is limited research on the successful removal and management of V. minor. The management practice of combined cutting and herbicide applications has been shown to be moderately effective, but further research into more aggressive means of management will be necessary as this species continues to spread and threaten diversity in forest ecosystems (Schulz and Thelen 2000). Herbicide impacts on surrounding native species is a concern in the management of periwinkle (Tatina 2015).
Allred, B. W., S. D. Fuhlendorf, T. A. Monaco, and R. E. Will. 2010. Morphological and physiological traits in the success of the invasive plant Lespedeza cuneata. Biological Invasions 12:739-749.
Bauman, J. M., C. Cochran, J. Chapman, and K. Gilland. 2015. Plant community development following restoration treatments on a legacy reclaimed mine site. Ecological Engineering 83:521-528.
Kibis, E. Y., and I. E. Buyuktahtakin. 2017. Optimizing invasive species management: A mixed-integer linear programming approach. European Journal of Operational Research 259:308-321.
Panasenko, N. N., and L. N. Anishchenko. 2018. Influence of Invasive Plants Parthenocissus vitacea and Vinca minor on Biodiversity Indices of Forest Communities. Contemporary Problems of Ecology 11:614-623.
Schulz, K., and C. Thelen. 2000. Impact and control of Vinca minor L. in an Illinois forest preserve (USA). Natural Areas Journal 20:189-196.
Schutzenhofer, M. R., T. J. Valone, and T. M. Knight. 2009. Herbivory and population dynamics of invasive and native Lespedeza. Oecologia 161:57-66.
Tanveer, A., H. H. Ali, S. Manalil, A. Raza, and B. S. Chauhan. 2018. Eco-Biology and Management of Alligator Weed Alternanthera philoxeroides) (Mart.) Griseb. : a Review. Wetlands 38:1067-1079.
Tatina, R. 2015. Effects on Trillium recurvatum, a Michigan Threatened Species, of Applying Glyphosate to Control Vinca minor. Natural Areas Journal 35:465-467.
Wu, H., J. Carrillo, and J. Q. Ding. 2017a. Species diversity and environmental determinants of aquatic and terrestrial communities invaded by Alternanthera philoxeroides. Science of the Total Environment 581:666-675.
Wu, H., M. Ismail, and J. Q. Ding. 2017b. Global warming increases the interspecific competitiveness of the invasive plant alligator weed, Alternanthera philoxeroides. Science of the Total Environment 575:1415-1422.
You, W. H., C. M. Han, L. X. Fang, and D. L. Du. 2016. Propagule Pressure, Habitat Conditions and Clonal Integration Influence the Establishment and Growth of an Invasive Clonal Plant, Alternanthera philoxeroides. Frontiers in Plant Science 7:11.