Be a steward of the Bog and get down and dirty in helping us combat invasive and protect the ecosystem in our Bog Guardian program.

The Friends of the Cedarburg Bog is a nonprofit 501(C)(3) organization that supports preservation, stewardship, appreciation, and scientific study of the Cedarburg Bog in cooperation with the Department of natural Resources and the University of Wisconsin-Milwaukee Field Station. The Cedarburg Bog is one of the largest and most biologically interesting wetlands in Southern Wisconsin. The Bog Friends seek to make the public more aware of the Bog’s uniqueness by creating opportunities for people to visit. It organizes projects and volunteer workdays for invasive species control; it improves facilities for educational and scientific programs, and supports long term monitoring and research.


While the Bog is a high-quality natural area, it continues to feel the threat of aggressive invasive plants. One in particular, glossy buckthorn, is a major threat to the integrity of many of the Bog’s communities. Unlike Common Buckthorn, which is a problem in upland plant communities, Glossy buckthorn is primarily an aggressive and damaging invader of wetlands like the Bog. Glossy Buckthorn is a tall, aggressive, and invasive shrub that has become extremely abundant in many parts and plant communities of the Bog. This Eurasian shrub produces bird-dispersed seed in fleshy fruits and was first reported in Wisconsin in 1943. Based on maximum stem ages found in studies here, it appears to have arrived in the Cedarburg Bog by about 1955. By the 1990s, Glossy buckthorn was most abundant in the southern portions of the Bog. Its extreme abundance suggested that it will ultimately have a negative impact on other members of the shrub community, plants that grow under its shade including herbaceous species, and the recruitment of native tree seedlings.

Since 1991, the Wisconsin DNR, the UW-Milwaukee Field Station, and the Friends of Cedarburg Bog (FOCB) have been working on projects to control and manage both buckthorn species in parts of the Bog. Since its founding in 2005, one of the primary stewardship activities of FOCB has been the control of buckthorn in representative examples of all of the Bog’s plant communities. Over $312,000 has been raised to cut and kill fruiting-sized buckthorn in 576 acres of the Bog as of 2021. The map shows all of the areas where fruiting buckthorn has been removed at least once. However, the work in these areas is not done. Removal of the fruiting-sized shrubs has prevented new seed from falling, but continued control projects will be required as the seedlings of buckthorn that are present reach mature size and begin producing fruit. The Friends of Cedarburg Bog is committed to protecting the important communities of the Bog. We will continue our efforts to raise funding and manage the removal of Glossy and Common Buckthorn within the Cedarburg Bog boundaries.

Treated Areas Map (click image to enlarge)

Below are links to various documents put together by researchers and FOCB regarding buckthorn control in the Cedarburg Bog:

Buckthorn Control Case Study

Buckthorn Control Sustainment Plan

Buckthorn Control Model Program

Buckthorn Control Summary-2019



The Bog Guardian program began in 2017 with funding from the Ozaukee Washington Land trust and the WI DNR — Citizens Based Monitoring Program. A group of volunteers conducted road surveys to locate invasive plants in a 28 square mile area around the Cedarburg Bog. The Bog Guardians are currently focused on what we refer to as the Big-4, Wild Parsnip, Teasels, Phragmites, and Japanese Knotweed. This map shows our 28 square miles Bog Guardian area and the initial 2017 mapping of the invasives.

Our focus is on these four invasive species because, 1) our volunteers have prevented them from ever really becoming established here, 2) they are very damaging in many parts of southeastern Wisconsin where they are abundant, and 3) they spread primarily along roadways.

Many roadsides surrounding our project area are dominated by one or more of the Big-4. Where they are abundant on the roadsides, they have also invaded the fields and wetlands off the road, degrading everyplace they grow. These invasive plants reduce aesthetics, habitat value, and property values. The effort to prevent colonization through yearly surveillance and removal of initial colonizers is relatively cheap. Whereas eradication and control of invasive species that are well established is VERY EXPENSIVE.

Bog Guardian Map (click image to enlarge)

The Cedarburg Bog neighborhood is exceptional because our roadsides, fields, and wetlands are still free from the Big-4. We have the opportunity to keep these plants (and others) from ever damaging our area. Roadsides like ours are becoming increasingly rare. It would be a shame if we just let the Big-4 take over the roadways of the Bog Neighborhood, and they surely will if we just sit back and watch! We work with surrounding Landowners to help identify and eradicate invasives on their own properties.

2021 was the fourth season during which we surveyed, mapped, and killed every plant of the Big-4 within our 28 square miles project area. The work to prevent all seed production of Wild Parsnip and Teasels was achieved with outstanding efforts of our volunteers. We would not have been able to achieve our goals without the support of our partners. The Ozaukee Washington Land Trust has applied herbicide to all of the known patches of Phragmites in the area. We have also received fantastic support from all the local highway departments and the electric transmission utilities in properly scheduled mowing of the biennial invasives to prevent seed production. These accomplishments mean that we have a fantastic start at keeping the Big-4 out of our area.

Becoming a Bog Guardian is easy and anyone can help!

We continue to look for volunteers to aide us in this effort. We also hope to keep engaging landowners and businesses to help us protect the beauty and the health of this precious Natural Area.

Click here to become a Bog Guardian volunteer!

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Volunteers are integral to the success and future of the Friends of the Cedarburg Bog (FOCB), including our BOD which is composed completely of volunteers lending their time and expertise to the organization. We have had important success with FOCB volunteers. Past initiatives include installing our boardwalks on the North and South ends as well as the interior of the Bog, removing invasive species to enable native ecosystems and communities to thrive, and organizing events to promote conservation and education. Join us in securing the future of this wetland gem and important bird area.

Leave A Legacy

Want to Make a lasting difference to the Cedarburg Bog? Consider contributing to the Friends of Cedarburg Bog Endowment Fund.

In 2012, The Friends of the Cedarburg Bog established a permanent endowment to provide a perpetual source of funding to support ongoing operations and initiatives. The endowment is managed by the Natural Resources Foundation of Wisconsin.

You can make a tax-deductible gift to our endowment in two ways:

You can send a gift to us directly.

Friends of the Cedarburg Bog, Inc.
c/o UW-Milwaukee Field Station
3095 Blue Goose Road
Saukville, WI 53080

You can send your contribution to the manager of our endowment fund–The Natural Resources Foundation of Wisconsin

—via the mail or through the NRF’s web site,, Donate Now, noting the intention of the gift.
Natural Resources Foundation of WI
Attn: The Friends of the Cedarburg Bog, Inc.
PO Box 2317
Madison, WI 53701

Bequests: Making a legacy gift to FOCB

A charitable bequest is one of the easiest ways you can leave a lasting impact on The Friends of the Cedarburg Bog.

A bequest may be made in your will or trust directing a gift to The Friends of the Cedarburg Bog, Inc. With the help of an advisor, you can include language in your will or trust specifying a gift to be made to family, friends, or Friends of the Cedarburg Bog as part of your estate plan.

Benefits of Your Bequest

Your Bequest Options: A bequest may be made in several ways:

If you love the Cedarburg Bog and its Friends, and want to help support it for future generations, consider leaving a legacy gift behind by including The Friends of the Cedarburg Bog in your will.

To leave a bequest, simply incorporate the following language in your estate plans: “I give [describe the gift] to the Natural Resources Foundation of Wisconsin [federal tax id #39-1572034], a nonprofit corporation organized and existing under the laws of Wisconsin and with a principal mailing address of PO Box 2317, Madison, WI 53701. This gift shall be designated to The Friends of the Cedarburg Bog, Inc.”

For more information, call the Natural Resources Foundation toll free at (866) 264-4096, email or visit