Dutch Elm Disease (DED) is caused by a fungus and is fatal to elm trees. When our Forestry Department determines that a publicly owned elm tree has DED, it must be removed.
Invasive species are species that are not native to Minnesota and cause economic or environmental harm or harm to human health. We are working to control several terrestrial (land-based) invasive species in our parks.
Emerald Ash Borer (EAB) is an invasive beetle that is killing ash trees in Minneapolis. It was first discovered here in 2010.
Buckthorn is a shrub brought into Minnesota from Europe in the 1800’s as hedge plants. Buckthorn is considered a restricted noxious weed by the Minnesota Department of Agriculture.
Garlic mustard (Alliaria petiolata) is a European plant brought to North America for use as a culinary herb. Its name comes from the strong garlic odor released when its leaves are crushed. Garlic mustard is a member of the mustard family. This plant family is known for its massive seed production and seed dispersal.
Garlic mustard thrives in woodlands and areas where garlic mustard is prevalent you can see a decline in native plants within ten years.
While not as invasive as buckthorn, honeysuckle and mulberry are being removed from woodlands because of their prolific fruiting. They are also transported by birds.
The presence of invasive plants can alter many functions of a native ecosystem. They can alter nutrient cycling, soil composition, hydrology and other ecological processes. They cause native plant communities to decline, and decrease biodiversity.
When introduced to a new ecosystem, invasive plants have an advantage over native plants. They are freed from the diseases, insects and other ecological influences that slow their growth in their native ecosystem and they beat native plants for limited resources. As a result, a previously diverse ecosystem may become a plant community of just a few species with the non-native species dominant.
Invasive plants may create safety problems in park areas. Dense areas of buckthorn, for example, reduce visibility along pathways and at intersections which reduces your enjoyment and sense of safety.
Many invasive plants were introduced from Europe and Asia either accidentally or intentionally, often for food, medicinal or horticultural values. Purple loosestrife, an invasive wetland plant, was planted in the 1920s to beautify wetlands. Non-native insect species like the emerald ash borer were first found in Michigan in 2002 and it is thought they were accidentally introduced in wood shipping crates coming from Asia.
Invasive plants can become established in many types of habitats but, in general, they are more likely to invade ecosystems that have been disturbed by human activity. Some invasive plants also produce allelopathic substances, “chemicals” released through roots, fruits or leaves that inhibit or prevent the growth and establishment of native plants.
Invasive plants are problems in both urban and rural areas worldwide.
The United States Department of Agriculture estimates that invasive species (both plant and animal) cause $130 billion dollars annually in losses to agriculture, forestry, fisheries, and the maintenance of waterways in the United States. With the global trade economy new invasive species introduction is an ongoing problem that scientists, land managers and policy makers must address.
Nationwide management efforts are aimed at invasive species prevention, early detection and control. Education about the harmful effects of invasive plants on our native ecosystems is essential for management efforts to be successful.
The Minneapolis Park and Recreation Board has identified priority areas for invasive plant management. The Environmental Management Department is concerned with managing invasive species in natural areas that still have ecological significance and semblance of a native plant community structure.
You can help by learning about invasive species. Do not plant invasive species.