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Invasive Plants in Our Area Is Bad News for a Variety of Reasons

Kudzu smothering plants and trees. Like bittersweet, kudzu can strangle and kill trees. This creates more sunlight openings and allows the plant to spread quicker. Photo from Invasive Species Initiative.

An ounce of prevention is worth a pound of cure. There are few examples where this old saying from Benjamin Franklin rings truer than with invasive plants. An invasive plant as defined by the Natural Resource Conservation Service is: “A plant that is both non-native and able to establish on many sites, grow quickly, and spread to the point of disrupting plant communities or ecosystems.” Most invasive plants here in western NC come from similar environments and ecosystems in Europe and Asia. Many invasive plants are brought here intentionally through nurseries and the landscaping industry. Some also arrive in products or as hitchhikers on vehicles, planes, and boats. Invasive species can dominate in ecosystems in which they are not naturally a part of because they do not have any checks and balances that limit population growth. These checks and balances include things like specialized predators, diseases, parasites, as well as environmental factors like certain climatic conditions. When a plant is moved to a new ecosystem and no longer has any natural checks or balances, its population can expand rapidly at the cost of its new ecosystem. 

Our native plants have checks and balances that keep them in check here within their native ecosystem as well. Northern red oak is an example of this. Here the tree is perceived as a beautiful common member of our forest. A variety of pests and diseases that are also native to this ecosystem keep it in check here. But in Europe where northern red oak has been introduced, it is proving to be a very invasive plant. This is because across the Atlantic, it does not have the limiting factors (checks and balances) that it has here in its native ecosystem.

Here in western NC, we have our fair share of invasive plants with new ones arriving regularly. Invasive plants are bad news for a variety of reasons. They disrupt natural ecological processes present in our local native ecosystems. This has many drastic and far-reaching effects. Invasive plants can outcompete native plants for resources like sunlight, water, and nutrients in the soil. Some invasives are able to kill native plants – for instance, even the strongest oak tree can be killed in a couple of years by oriental bittersweet. This creates further sunlight openings and space where the invasive plant can dominate even more. Some invasive plants are hosts for invasive insects. This is seen with the tree of heaven acting as a host for the destructive spotted lanternfly. 

Even if an invasive species does not completely take over an area, but is still present, ecosystem diversity still decreases drastically. A less diverse ecosystem is far more susceptible to disease, further invasive species colonization, drought, extreme wildland fire, and other disturbances. Less diverse ecosystems are not able to support nearly as much life. This includes everything alive in our native ecosystems from wildflowers, trees, insects, fish, birds, amphibians, mammals and much more. Invasive species have led to the extinction of native species. 

Japanese knotweed. This plant easily establishes itself in many environments, including streams and riverbanks. The plant has a deep root system and can regenerate from cut pieces of the stem. Mowing often spreads the plant along roadways and other open areas. Photo from W. Carter

Invasive plants have large economic impacts. The damages they cause result in outreaching effects and outcomes. It is incredibly costly to remove invasive plants. Invasive species can greatly affect property value. In many cases, if invasive plants reach high levels, it can cost more per acre of land to remove invasive plants than the acre is worth. Invasive plants negatively impact a variety of industries including farming, forestry, mining, tourism, public utility operations, among others. 

Ranger Frank Blankenship, states: “Several harmful invasive plants are spreading rapidly in our area. For suppression efforts to be effective, invasive plants need to be controlled on the landowner scale. Oriental bittersweet, Japanese knotweed, and tree of heaven are currently the most abundant in the area.” 

Certain invasive species can greatly impact water quality and water availability by increasing plant water use, erosion, and stormwater runoff. This in turn degrades the water quality and drives up the costs for treating water, an impact which is passed on to the general population. We are experiencing this locally with Japanese knotweed, oriental bittersweet, and kudzu. All these plants outcompete and kill the native plants that hold the streambanks in place and form buffers along our streams and rivers. Once these buffers are gone, the streambanks begin to erode quickly. This greatly impacts water quality, but also leads to an increase in flooding, and loss of land and property. Some invasive plants such as silver grass burn very easily and are leading to more intense wildland fires in western NC. 

Some of the worst invasive species present in northwestern NC are listed below. Many of these plants also have other common names. It is worth looking up and learning to identify each of these plants: 

  • Oriental bittersweet, Celastrus orbiculatus
  • Autumn olive and russian olive, Elaeagnus umbellata, E. angustifolia
  • Japanese knotweed, Reynoutria japonica
  • Chinese privet, Ligustrum sinense
  • Bush honeysuckle, Lonicera tatarica
  • Japanese barberry, Berberis thunbergii
  • Periwinkle, Vinca spp.
  • Tree of heaven, Ailanthus altissima
  • Princess tree/foxglove tree, Paulownia tomentosa
  • Japanese honeysuckle, Lonicera japonica 
  • Winged burning bush/hearts-a-bustin, Euonymus alatus
  • English ivy, Hedera helix 
  • Multiflora rose, Rosa multiflora 
  • Mimosa/Silk tree, Albizia julibrissin
  • Silver grass, Miscanthus sinensis
  • Japanese stilt-grass, Microstegium vimineum
  • Kudzu, Pueraria spp.

All of these, along with many other invasive plants, are present here in northwestern NC. If you are interested in learning more about invasive plants in NC, the North Carolina Native Plant Society has a very easy to interpret list of invasive species. That list can be found at: https://ncwildflower.org/invasive-exotic-species-list/. 

Many invasive plants are still sold in nurseries. This includes many of the plants listed here. If you are landscaping or buying plants for your garden, consider using native plants. There are several nurseries in the area that specialize in native plants. We have an amazing diversity of beautiful native, flowers, shrubs, and trees that are great for landscaping and will help protect our watershed and offer great wildlife and water ecological benefits. If you choose to plant nonnative plants, consider doing research to insure you won’t end up with a large problem down the road. I receive a lot of calls from folks who planted something 20 years ago, and it has now taken over their garden and yard or is killing the woods behind their house. If you already have something on your property, it may be worth removing it now before it gets worse. It is a case of an ounce of prevention being worth a pound of cure! 

Oriental bittersweet. Photo from USDA National Invasive Species Center This plant will choke out even the toughest of native plants and trees. It has bright red berries that ripen in the fall. Birds will eat these berries and disperse the seeds.

Water Resources is an article series supported by local watershed partners highlighting watershed and community news. The High Country and Toe-Cane Watershed Coordinator positions work to improve water quality and gain associated economic benefits in the watershed by providing education and technical resources and implementing on-the-ground projects. Please see our website for updates on projects, and helpful documents for addressing water related issues: http://www.blueridgercd.com/ or contact: 

Blue Ridge Resource Conservation & Development

Jessica Janc, High Country Watershed Coordinator in Watauga, Ashe, Alleghany, and Wilkes Co.

hcwatershed@gmail.com, 828.406.6690

Felix Stith, Toe-Cane Watershed Coordinator in Yancey, Mitchell, and Avery Co.

toecane.edu@gmail.com, 828.279.2453