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. Invasive species that live in the water are called aquatic invasive species.
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.
The Dane County Land & Water Resources Department manages an aquatic plant harvesting program for county waters. Harvesting follows permit requirements from the Wisconsin Department of Natural Resources (WDNR) and approved Aquatic Plant Management Plans for each waterbody. The county's policy is to cut and harvest Eurasian water milfoil and other invasives to help provide for reasonable recreational use of the lakes for boating, fishing and swimming, and lake level management, while preserving the health and balance of the lake ecosystem. Visit the Aquatic Plant Management page to learn more.
Dane County Parks manages nearly 13,000 acres of land and invasive species management is a top priority. 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 mowing’s are conducted with a 15ft. 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.
Another species we treat with this mowing procedure is Canada Thistle. Although it 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.
Many of our friends groups also work 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 page to learn how.