Wirth Park Habitat Enhancements

Theodore Wirth Regional Park was established more than 100 years ago to protect natural resources. Wirth's total 750 acres consist of wetland, woodland, savanna, shoreline and lake habitats. These habitats provide for a variety of wildlife including mammals, reptiles, amphibians, pollinating insects, fish, and migratory birds within a fully developed urban metro area. 

The Eloise Butler Wildflower Garden and Bird Sanctuary, established in 1907 as a public wildflower garden to view Minnesota native plants and as a sanctuary for birds, is found in the southern portion of the park. A  tamarack bog, a wetland plant community that is rare for the southern part of the State, is also found in the southern portion of the park within the project area. The tamarack bog and the Eloise Butler Wildflower Garden and Bird Sanctuary provide unique outdoor experiences for urban dwellers. Migratory birds use Wirth Park as a stopover on their migratory route the Mississippi flyway, just three miles to the east. Recently Wirth Park and Minneapolis Chain of Lakes Regional Park were designated an Important Bird Area by Audubon International for this reason. 

When Wirth Park was established more than 100 years ago the land was not impacted by non-native invasive plants. Times have changed and Wirth park's oak forest is dominated by common buckthorn. Wetland areas as well have dense stands of both common and glossy buckthorn. Activities funded by the Outdoor Heritage Fund (OHF) included removal and control of invasive species in forest and wetland habitats and enhancement plantings with native plant species.  Since 2005, Minneapolis Park and Recreation Board's (MPRB) Citizen Advisory Committees have consistently listed natural resource enhancements as top priorities for Wirth park and are a key component of the Wirth Park Master Plan. 

Contracted work for the grant occurred from 2015-2016 and included saw cutting and forestry mowing of woody invasive species. Control of buckthorn in the oak forest and wetland areas consisted of cutting down large mature buckthorn with a chain or brush saw and treating the stump with herbicide. Due to the density of mature buckthorn in certain areas, the resulting brush resulted in large quantities of cut brush littering the landscape, making these areas impossible to access.  In these situations the brush was chipped and left in place. Brush chipping allows for better access into the area for future control of invasive species and enhancement plantings.  

In forested areas where there was low density of large mature buckthorn, forestry mowing was done through contracted services with a forestry brush mower.  Where there were steeper slopes that a forestry mower couldn't safely operate, a brush saw was used. In 2017, the MPRB  tried for the first time goat browsing to control invasive species through contracted services. The goat browsing occurred for three consecutive years (2017-2019) with one annual browsing occurring during the summer (June or July) in two locations in the oak forest.  Forestry mowing, brush sawing and goat browsing all served to control the seeding of woody invasive species.

Oriental bittersweet has become an increasingly prevalent non-native invasive species in many park areas.  Oriental bittersweet was first found in Wirth Park by MPRB staff in 2013 and has been reported to the Minnesota Department of Agriculture through eddmaps.org.  It is found in the OHF project area and was part of invasive species control for this project. Control of mature Oriental bittersweet stems, where vines were entangled in the tree canopy, consisted of cutting the stem and treating the stump with an herbicide. Monitoring of the area occurred and any seedlings that sprouted were treated with herbicide to prevent maturation.

The wetland areas to the south of Glenwood Avenue are a unique natural resource that are part of a groundwater system which once provided water for the Glenwood Inglewood spring water plant.  There is open water and seepage in this area throughout the  seasons, making work in this area difficult.  Common and glossy buckthorn are prevalent invasive species in this area as well as purple loosestrife. Purple loosestrife control through biological controls has been in place in Wirth park since the 1990s and is working well to control the plant in both the Glenwood wetlands and the wetland edges of Birch pond. Buckthorn removal occurred in the Glenwood wetlands during the winter and early spring months when the ground was more frozen. Buckthorn in these areas was hand cut and treated with an aquatic approved herbicide.  As much brush as possible was chipped and left onsite. Record snowfalls during the winter of 2018-19 and record rainfall in 2019 made this area very difficult to work in.

The OHF project received assistance from the Conservation Corps Youth Outdoors (CCMI YO) program. CCMI YO adult and youth crews worked on invasive species control and planting enhancements from 2017 until the close of the grant in June 2019.  Adult crews hand cut mature buckthorn from woodland and wetland areas. The youth program participants helped by hand pulling invasive species and piling brush for later chipping.  Youth program participants also seeded in prairie grasses into areas that will be maintained as oak savanna.