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Invasive Shrubs And Why We Control Them

By Ryan Colliton, Manager of Natural Resources and Regulatory Compliance 

The Metroparks is celebrating its 75th anniversary this year, continuing our mission of providing excellent recreational and educational opportunities while serving as stewards of its natural resources. A critical part of this mission is to provide for and steward the protection of various ecosystems present throughout our 13 parks. The Huron-Clinton Metroparks is home to a wide variety of ecosystems that support an abundance of native plants and wildlife.

One of the major threats to ecosystem integrity in Southeast Michigan is the presence of invasive species. Invasive species are defined as species that are not native to this area, and have the potential to cause economic or environmental harm, or harm to human health. A major problem with invasive species results from their rapid spread and quick growth in our ecosystems. Having developed in a different place the natural controls, which would limit their growth and spread in their home range, are not present in our environment. These species grow quickly from just a few individuals to become a real problem.

Invasive shrubs present a particularly challenging problem for Natural Resource managers at the Metroparks, as they can be present in almost all habitat types we steward. Invading prairies and pushing out native plants, dominating the forest understory, and encroaching on native wetland plants, these shrubs are an ever-present threat to native species biodiversity. Some of the most problematic species include Autumn Olive (Elaegnus umbellata), various species of Honeysuckle (Lonicera spp.), Japanese Barberry (Berberis thunbergii), and common and glossy buckthorn (Rhamnus cathartica and frangula). Natural Resource managers control these shrubs through a variety of methods depending on site characteristics and species of invasive shrubs present.

Mechanical control methods include cutting, grinding, and burning of invasive shrub populations. These methods provide preliminary or follow-up control generally, as they will not effectively remove the shrubs long-term. Chemical control methods are used to target the roots and leaves of plants, where herbicides are specially formulated and applied to control only targeted species. The Metroparks has to balance a wide variety of stakeholder needs and natural resources priorities when controlling invasive shrubs in our parks. Using a method known as Integrated Pest Management, or IPM, Metroparks Natural Resource managers use a variety of methods to strategically control invasive shrubs. This approach allows us to minimize effects on desirable native communities, maximize impact on target invasive species, and align our efforts with the recreation priorities and safety concerns of park users.

While invasive shrubs are sure to be around for many years to come, the focus on their management at the Metroparks ensures that our high quality natural resources and the ecological functions they provide to the residents of Southeast Michigan will continue to flourish. Metroparks Natural Resource managers continue to research and employ the latest best management practices (BMPs) for shrub control in our parks. Management of these invasive shrubs will ensure the continued preservation of native biodiversity, and enjoyment of plant and wildlife by our many park patrons for the next 75 years at the Huron-Clinton Metroparks.

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