Land Care Report: Skunk Cabbage Wetlands and Winter Restoration Progress

Area between Arboretum Drive and Lake Wingra shoreline cleared of invasive brush.

Area between Arboretum Drive and Lake Wingra shoreline cleared of invasive brush.

Winter and early spring of 2023 were an exciting time for the land care crew and their oak savanna and wetland brush clearing projects. In 2016, the Arboretum started to focus on restoring Skunk Cabbage Wetlands, down the hill east of Wingra Woods, along the creek that flows through the area between the woods and the road. This project was planned with four phases, beginning with clearing along Arboretum Drive, and this winter the crew began the fourth and final phase.

Phase four has entailed working northward from the cleared area along the road toward the southern shore of Lake Wingra, and then working west along the lake, starting near where Covall and Balden streets intersect Arboretum Drive. The work in this area has focused on removing invasive brush like buckthorn and honeysuckle from the understory of the white and red oak trees. Many of these trees have wide sprawling canopies, indicating the presence of a historical savanna. In addition to the invasive species, some smaller native trees such as elm and black cherry were selectively removed to allow more light to reach the ground and help native wildflowers like skunk cabbage, closer to the lake, and shrubs like highbush cranberry farther up the slope. As they worked closer to the lake shore, the crew noticed evidence of a spring that feeds the lake. And in the project area this spring, the crew has already seen an increased density of spring ephemerals such as mayapple, skunk cabbage, and toothwort.

The crew was also doing notable project work south of the Beltline. In the middle of the Grady Tract, there is a remnant dry sandy prairie and savanna unit we call the West Knoll. This type of prairie and savanna is extremely rare in southern Wisconsin and is becoming more so. Over time, many red and black oaks encroached on the West Knoll and grew to shade out original vegetation like wild lupine and large-flowered penstemon. From December 2022 to early March 2023, the land care crew used chainsaws and a tractor-mounted tree winch to clear many large trees from the west side of the knoll. Recently they burned the West Knoll to further stimulate native vegetation and discourage invasive trees and shrubs from coming back. The current objective is to continue working south along the west side of the knoll and keep thinning the oaks to connect the clearing to Greene Prairie.

The crew also worked out at Lodde’s Mill Bluff, an outlying property located in Sauk County, to continue clearing invasive eastern red cedar trees from the bluff prairies. Because of a decades-long absence of fire, cedar trees have been able to overtake sections of the remnant prairies. There are two south-facing bluff prairies located on the eastern and western parts of the property. The crew has been clearing on the western side for the past couple of years, and this season they were able to begin clearing on the eastern part. Prescribed fire has also been reintroduced to the prairies the last couple of years to help reduce invasive species and to encourage native ones. With the added sunlight from clearing the cedars and the reintroduction of fire, native plant species such as prickly pear, purple prairie clover, leadplant and wild columbine have benefited and expanded.

Lastly, this winter the land care crew extended the Lost City Forest oak savanna and woodland restoration project that they started in winter 2021–22. Lost City Forest has a substantial invasion of buckthorn and honeysuckle, as well as non-native bittersweet vines choking and killing the oak trees. During the first winter, the crew forestry mowed approximately 7 acres of invasive buckthorn and honeysuckle adjacent to the eastern boundary of Teal Pond Wetlands. This year they mowed an additional 5 acres, progressing farther north past Teal Pond and Icke Boardwalk and meeting up with the southern end of Gallistel Woods. Last year before the crew did any seeding in the area, they noticed remnant savanna species returning on their own. Large portions of the mowed section already sprouted Canada wild rye, bottlebrush grass, hyssop, and wild bergamot. To help stimulate this restoration, the crew also seeded it with hundreds of pounds of seed in December.

An area of the Lost City Forest cleared of nonnative shrubs in winter 2021–22. (Photo: Chris Kregel)

The current project footprint is now approximately 12 acres and in future years the crew will continue to expand restoring the savanna and wetlands along Teal Pond, Gallistel Woods, and the creek edge northward toward Skunk Cabbage Wetlands. The crew also introduced prescribed fire to approximately 2.5 acres of the 2021–22 Lost City clearing this spring. As far as anyone knows, this was the first prescribed fire in that part of Lost City in the Arboretum’s history (there were also research burns conducted in a different part of Lost City in spring 2022 and 2023).

In the future, the crew looks forward to expanding the amount of burning done in Lost City as the restoration area expands.

—Land care staff: Chelsea Camp, Chris Kregel, Balin Magee, Lance Rudy, and Michael Hansen