What are non-native invasive plants?
People have been moving Earth’s plants from place to place for centuries. Many of the exotic plants we have introduced to our landscape by intention or accident have been beneficial to us and have had no unfortunate ecological impacts on natural communities. But a small percentage has spread from where they first became established, and have become serious threats to wetlands, shale barrens, prairies, glades and other rare ecosystems. Invasive plants often get started in areas disturbed by such human activities as road and trail building, timbering, mining, and other tasks that remove native vegetation, disturb the soil, or dramatically change the amount of sunlight or moisture that strikes the land. From such situations, a relatively small number of invasive species have moved into natural areas. These species have reproduced rapidly, forming stands that exclude nearly all other plant species. In the worst cases, they radically altered the ecosystem processes, altered natural areas, and displaced native species.
Concerned citizens have long been sounding alarms about the effects of pollution and misuse of land on our native plant and animal communities. Recently, increasing concern has been expressed that non-native plant species are invading and changing natural areas. These aggressive “weeds” are non-native invasive plants, sometimes referred to as exotic pest plants.
How do they differ from native species?
Generally, the native plant species of West Virginia are those that were part of plant communities when North America was first settled by Europeans. Change in plant communities is a natural part of life. As Dr. John Randall (The Nature Conservancy) and Janet Marinelli (Brooklyn Botanic Garden), point out in their handbook Invasive Plants: Weeds of the Global Garden (Brooklyn Botanic Garden Publications, 1996), “New species move in as the climate changes and as soils build up and become richer, or erode and become less fertile. In the normal course of events, the arrival of new species may be the result of a single catastrophic event like a hurricane, or of gradual change over thousands of years. Humans have vastly accelerated the movement of plants, carrying thousands of species that could not have crossed natural barriers like oceans, mountain ranges and deserts, to new areas. Species that have flourished and spread on their own, only after people transported them across barriers they could not otherwise surmount, are considered non-natives. In many areas these plants have overwhelmed the native plants and animals.”
We Value Natural Areas
Natural areas are generally areas of limited development where natural occurring, functioning ecosystems are supporting the greatest amount of natural biological diversity the nonliving resources (soil, sunlight, minerals, etc.) of that area can support.
Healthy natural areas have seemingly endless interrelationships among animals, plants, fungi, microorganisms, and the nonliving part of the ecosystems, providing habitat for these species.
Natural areas often support rare, threatened and endangered species of plants, animals, and fungi. The natural communities themselves are often rare enough or of such quality that society recognizes the value of conserving them.
Natural areas are valuable part of the global landscape from which future generations can continue to learn. Areas such as Cranberry Glades, Cranesville Swamp, shale barrens, limestone glades, and riverine marshes, to name a few, are West Virginia examples.
The impact of non-native invasive plant species on natural biological diversity, in numerous examples around the world, have reduced available habitat for native species and/or eliminated associated native species altogether.
What Challenges are there in controlling invasive plants in West Virginia?
The number of non-native invasive plant species in West Virginia is rising.
Six-hundred sixty-three species, 28% of vascular plants found in West Virginia outside the cultivation, are non-native. Each year, ecologists become more aware of the number of invasive plant species within the state and the threats they pose to natural communities.
Native stock plants are just becoming available.
Many agencies and private landowners are beginning to explore native alternatives for conservation purposes on public and private lands, and some West Virginia nurseries are beginning to sell varieties derived from West Virginia communities to be sold as alternatives to exotic species. The West Virginia Wildlife Resources Section has begun testing species for suitability in agency projects.
Examples of Non-Native Invasive Species
Garlic mustard, Japanese honeysuckle and kudzu, which invade moist forest edges, even those without disturbance.
Purple loosestrife, an incredibly invasive exotic now blanketing emergent wetlands along the Ohio River, and increasing along other major rivers throughout the state, in some cases replacing native vegetation, threatening rare plant species, and destroying small wetlands.
Mile-a-minute, a spiny vine found climbing 10-20 feet into trees, often smothers native shrubs and shades out herbaceous plants along the Ohio River and in the rivers of the Eastern Panhandle.
Japanese knotweedand sachaline knotweed are two stout perennial clonal herbs that can out-compete all other vegetation in certain areas.
Spotted knapweed, barren brome and tree of heaven are invading shale barrens, limestone glades, and barrens, and native grassland communities.
What can we do?
– Become aware of the differences between native and non-native plants and the potential for invasive species damaging native ecosystems. The following items are available from the West Virginia Division of Natural Resources, Wildlife Resources Section:
– Checklist of the Vascular Flora of West Virginia (a checklist of the native and naturalized vascular plants of the state)
– Native Shrubs in Wildlife Landscaping (a series of information sheets about the use of 50 native shrubs in wildlife planting, produced by the West Virginia Native Plant Society and the West Virginia Wildlife Diversity Program)
– A list of plant companies within the mid-Atlantic region, from which alternative native stock can be purchased
– Encourage all of us to evaluate in advance the wisdom of introducing non-native plants into our state on a case by case basis
– Minimize habitat disturbance in natural areas, reducing the chance for invasion by non-native aggressive plants.
– In extreme cases, consider the eradication of highly problematic non-native invasive plant species, (after careful consideration of the potential consequences of such actions on the entire ecosystem involved and the likelihood of success). In less severe cases, consider trying to minimize the impact of the invasive plant on the natural area.
– Help educate individuals of the seriousness of the problem.
– Continue to explore the use of native plant species in the management of public lands.
Who is helping?
The West Virginia Native Plant Society (WVNPS) has begun encouraging nurserymen to cultivate plants native to West Virginia that could be used in conservation and ornamental projects throughout the state as alternatives to non-native invasive plant species.
The West Virginia Native Plant Society’s “Grow Native” Committee and Wildlife Diversity Program have developed an informative slide show about invasive plants and how to learn more. The West Virginia Native Plant Society and the West Virginia Garden Club, Inc. plant to sponsor workshops on identifying problematic plant species.
To receive additional information about invasive plants, please contact:
West Virginia Division of Natural Resources
Wildlife Resources Section
P.O. Box 67
Elkins, WV 26241
Voice: 304-637-0245, fax: 304-637-0250