Are Invasive Plants Really A Problem In Missouri???
Tim Banek, MDC
Let’s start with the definition of an invasive species. The National Invasive Species Council defines an invasive species as: “A species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” Does that mean all non-native plants are bad? Certainly not, in fact a very small percentage (2-3%) of the over 800 plants introduced into Missouri are considered invasive. Many non-native plants are not invasive and support human livelihoods or a preferred quality of life. Nearly all of the crops that are used for agriculture in the United States were introduced from other countries. Although the percentage of non-native plants that are invasive is relatively low, the detrimental effects and costs related to the damage invasive plants cause are very high. The most widely referenced paper (Pimental et al. 2005) on this issue reports that invasive species cost the United States more than $120 billion in damages every year. To complicate matters more, invasive plants cause both direct and indirect effects that are often difficult to equate to a dollar value.
|Bush honeysuckle infestation in Missouri.|
Photo by Larry Rizzo
Invasive plants are aggressive, prolific, outcompete and displace native plants that provide the necessary food and habitat for native animals. Invasive plants arrive in Missouri in one of two ways: intentionally or accidentally. The global economy of today’s world means that species from all over the world can unintentionally be transported to the United States and to Missouri as hitchhikers on or in imported cargo shipments. However, some of the worst plant invaders such as, bush honeysuckle and autumn olive have been introduced intentionally for landscaping, herbal uses, wildlife benefits, erosion control, or wastewater treatment. The aggressive, competitive characteristics of invasive plants are such that they threaten the stability of ecosystems by reducing biological diversity and replacing beneficial native species with non-native plants that don’t provide the same ecosystem functions necessary to support native animal species and sustain life. One common belief is that the United States is blessed with ample public lands to support nature and provide the ecosystem functions necessary to maintain our native species. While Missouri is fortunate to have a great deal of public land, 93% of Missouri’s landscape is privately owned. Habitat destruction and invasive species are the two largest threats to biodiversity and native plant communities in the United States. Habitat destruction is occurring at the rate of 6,000 acres per day or 2.2 million acres annually resulting in habitat fragmentation that is continually reducing the amount of habitat available to support wildlife populations.
So what can Missourians do to reduce or reverse the effects of invasive species? Landowners could reevaluate the choices that they make for landscaping. It will certainly be a cultural change, but landowners should consider factors other than solely the appearance of plants used for landscaping. It seems that most homeowners would like to enjoy birds, butterflies and other wildlife to enhance their landscapes and the enjoyment of their private spaces. Homeowners can choose to use plants that support wildlife and provide habitat that will help to connect parks and public lands. Ecosystem functions such as, food-web value, watershed value, soil restorative properties, carbon sequestration and weather moderation are some of the functions that could be considered. For example, Missouri’s state bird, the bluebird, relies on insects to provide food to exist. Approximately 4,800 insects are needed to raise a clutch of bluebirds. Missouri’s native oaks and maples support between 400 and 500 insect species that provide food for many insect-eating birds, while the invasive golden rain tree supports only one known native insect species. Many beautiful butterflies and moths require specific native host plants. Exotic invasive species commonly used for landscaping such as, Bradford pears, bush honeysuckle, Japanese barberry, burning bush, winter creeper, privet, tree-of-heaven, amur maple, golden rain tree, etc., are not only detrimental when they escape and invade our native plant communities, they don’t support the ecosystem functions that native plants provide.
It would be great if only native plants were used in the landscape trade, but it would be a huge step to plant mainly native species, reduce grass areas and restrict non-native plants to plants that are not invasive that are used in only limited areas of the landscape. A book titled Bringing Nature Home by Dr. Douglas Tallamy is an excellent resource to provide information on reasons to use native plants and plant species to select that benefit native wildlife. Another resource is the Grow Native! program administered by Missouri Prairie Foundation that can be found at the following website: www.moprairie.org/ The Midwest Invasive Plant Network updated their Landscape Alternatives for Invasive Plants of the Midwest brochure and developed a free I-phone and I-pad app based on the brochure that can be found by searching for Landscape Alternatives in the Apple App Store or at www.apps.bugwood.org/apps.html .
Timothy J. Banek
Invasive Species Coordinator
Missouri Department of Conservation
PO Box 180
Jefferson City, MO 65102
(573) 522-4115 ext. 3371