Seal of Dane County County of Dane
Dane County Land & Water Resources Department

Invasive Species Management

What are Invasive Species?

People move organisms around all the time.  Sometimes when a non-native species is brought into a new area, it may spread rapidly and widely throughout the area and cause major harm to the native ecosystem and humans.  When non-native plants, animals, or pathogens quickly take over a new location and alter the ecosystem, they are considered to be invasive species.

How do they become a problem?

One of the reasons that invasive species are able to thrive in a new ecosystem is that they often do not have the predators and competitors they had in their native ecosystem.  Without these natural checks and balances they are able to reproduce rapidly and out-compete native species.  The net result is a loss of diversity of native plants and animals as invasive species multiply and take over. Invasive species are the second most significant reason, after habitat loss, for the loss of global biological diversity.

Terrestrial Invasive Species Control and Removal

Invasive Species management is a top priority for the Dane County Park System. The Dane County Integrated Pest Management Plan (PDF) guides the management of invasive species within the Dane County Park System. Some parks also have detailed vegetation management plans to provide more detail about management techniques and habitat goals for that location.

The type of management required depends on the species and location. Management options could include cutting, prescribed fire, mowing, herbicide, and biological control. Typically a mix of management options combined with seeding or planting the area in native plants after the invasives are removed provides the most successful and longest lasting benefits.

Manual Removal and Cutting
Manual removal and cutting can be very effective but requires a huge amount of time and labor. Many of our friends groups host workdays in our parks to remove invasive species by hand in areas that need special attention. If you are interested in getting more involved with a friends group and helping with these efforts, visit the Dane County Parks volunteer webpage to learn how.

Prescribed Fire
This is the best and most lasting of the methods. It requires a high level of training and is most often done in spring before the vegetation starts to grow.

Biological Control
Biological controls have been used on a limited bases. An example of a biological control is the use of root-mining weevils that are propagated and released to control Purple Loosestrife, an exotic invader to our wetlands.

Goats can also be used to control invasives. A single goat can eat 8 pounds of vegetation a day including brush and leafy greens making them super stars at clearing out thick invasive species in rocky areas that cannot be managed with mowing.

Herbicides are another tool for managing undesired and invasive plants in natural areas. When used with caution and precision, herbicides do far more good than harm for natural areas. Herbicides are only applied by staff or volunteers who have obtained a Wisconsin Pesticide Applicator certification. For woody invasives, such as buckthorn and honeysuckle, they are spot applied directly to cut stumps to minimize the quantity used. When herbicides are used at a dog park, the park will remain closed through the duration of the Restricted Entry Interval (REI) as indicated on the herbicide label. Signs are posted in areas where chemicals have been applied to notify the public.

Wild Parsnip, Canada Thistle and Sweet Clover are some of the invasive species we manage with mowing to help reduce their rate of spread. These mowings are conducted with a 15 foot batwing mower towed behind a tractor which allows us tackle larger areas and manage more of our lands. The large size of the equipment makes it challenging to be selective with the mowing but we do our best at avoiding desirable prairie species if possible. The perennial prairie plants will grow back after being mowed and removing the invasive species often creates a better environment for them to grow.

Although Canada Thistle is a desired food source for gold finches, it is considered a RESTRICTED invasive species by the WI DNR which means we need to do our best to keep this species from spreading by mowing before it releases seeds. With property timed mowing, we can help prevent these invasives from going to seed and keep their populations more manageable allowing perennial prairie plants time to grow. Our ultimate goal is to keep these invasive species at bay in order to keep the integrity of the prairie intact.

Emerald Ash Borer and Wood Utilization Plan
Outlines proactive steps that helped prepare for the arrival of emerald ash borer in order to reduce the environmental impacts, reduce economic and social costs, and find ways to put “waste” wood to positive and profitable use.

Aquatic Invasive Species Management

Invasive species that live in the water are called aquatic invasive species. Once invasive species are present in a waterbody it can be very difficult, if not impossible, to remove them. Prevention is the best method for controlling aquatic invasive species. Learn more about aquatic invasive species management in Dane County using the resources below:

  • Aquatic Invasive Species Prevention and Control Plan (PDF): addresses prevention and control strategies for aquatic invasive species. The Dane County Land & Water Resources Department manages an aquatic plant harvesting program for county waters.
  • Clean Boats, Clean Waters Statewide Program: collects data and educates aquatic users about aquatic invasive species and how they are spread. Data collected from Dane County is available on the DNR website.
  • Carp Removal Projects: The department has assisted with various studies and removal efforts on Lake Wingra, Cherokee Lake, Indian Lake, Lake Kegonsa, and Mud Lake.  Various methods, including chemical and physical operations, have removed an estimated 800,000 pounds to date.  Carp are detrimental to water quality and disturb habitat for native aquatic plants and animals.