Every Invasive Species Is a Unique Conservation Challenge for Dane County


The Dane County Land and Water Resources Department has done many projects that have helped reduce the number of invasive species. Staff work to prevent the invasive species from reproducing and keep their populations manageable. Their main goal is to keep invasive species in check, “in order to keep the integrity of the prairie intact”.

When non-native plants/animals are brought to a new area, they can quickly take over and change the ecosystem. When this happens they are considered invasive species.

Invasive species may also spread fast and extend their population. They can cause crucial harm to the biodiversity in the ecosystem and human health. One reason this happens is that often invasive species don’t have predators/competitors in their new location. Because they lack predators, it’s difficult to keep their population balanced. Without any natural balance, they’re able to multiply quickly and outcompete native species for resources. The result is “a loss of diversity” of native plants/animals as invasive species reproduce and take over.

Dane County Parks manages over 12,000 acres of land across Dane County. Wild parsnip, Canada thistle, and sweet clover are some of the invasive plant species Dane County controls with mowing. Properly timed mowing can help prevent invasives from going to seed and keep populations more manageable allowing perennial prairie plants time to grow.

Dane County uses a large, 15ft batwing mower towed behind a tractor. The large size allows Dane County to handle bigger areas and manage more of Dane County lands. The size of the equipment makes it difficult to be selective with the mowing and avoid desirable prairie plants, which should be allowed to grow as much as possible. Staff do their best to avoid these species but even if prairie plants are mowed they will grow back. Removing the invasive species often creates a better environment for native plants to grow

Mowing is effective, but the timing is very important. Dane County Parks staff mow usually every week or month, depending on the invasive plant. Mowing too early or too late can make the problem worse.

An example of an invasive plant that needs careful timing is the Canada thistle. It is considered a ‘RESTRICTED invasive species’ by the Wisconsin Department of Natural Resources (WI DNR). This means this plant has to be kept from spreading by mowing before it releases seeds.

Besides mowing, there are other techniques to remove invasive plants and insects on land. Prescribed fire is one easy method to use on plants. Taking it out by hand is another simple, though labor-intensive option. Chemical removal for invasive insects is another choice, but chemicals may also harm native plants and insects.

Biological control is another way, but it is a very risky process. It’s a process where the invasive species’ natural predator is introduced in order to control the species. An example of biological control is when beetles are brought to an area infested with invasive plants. An example of this that has shown a lot of success is using the Galerucella beetles to help control purple loosestrife. The beetle can dig down and eat the root, therefore killing the plant. It may take many years to fully get rid of the undesirable invasive species, or even reduce the population.

Invasive species are not limited to only the land. Management projects also include the Aquatic Invasive Species Prevention and Control Plan, and Carp Removal Projects. The plan has 3 main goals: 1) Prevent the introduction of AIS in Dane County waters. 2) Initiate management strategies to decrease the spread of existing AIS in Dane County waters and other counties. 3) Abate or if possible, eradicate the effects caused by AIS in Dane County waters.

Carp impact water quality and disturb the home of native aquatic plants and animals. LWRD has done many removal efforts on Lake Wingra, Cherokee Lake, Indian Lake, Lake Kegonsa, and Mud Lake. Several methods, including chemical and physical procedures, have already removed nearly 800,000 pounds.

Invasive species pose a natural resources management challenge. Experts work year-round to mitigate impact and protect our environment. Every invasive species requires its own unique management plan; there is no 'one-size-fits-all' solution.

Click Here to Learn More About Invasive Species Management in Dane County

[Sources: Dane County Department of Land and Water Resources; Chicago Tribune; Madison.com]

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