Gorge Stewards Quarterly — Summer 2005

In this issue

• Participants pull together during Garlic Mustard Days
• Volunteers put down roots in the Prairie Bowl
• Volunteers come out of their shell for woodland seed collection
• The scourge of the Gorge

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Participants pull together during Garlic Mustard Days

There are fewer garlic mustard plants in the Mississippi River Gorge thanks to 199 volunteers who helped out during the Gorge Stewards Garlic Mustard Days this spring. In Longfellow, Merriam Park, and Highland Park neighborhood volunteers gathered in April and May for pulling events. While volunteers helped improve habitat for native plants and wildlife, they also enjoyed the blossoms of spring ephemerals, birdsong, and the bud break of our urban trees.

While many gorge areas are infested with garlic mustard, Gorge Stewards focus on high traffic areas, sites where restoration is underway, or areas where there are still a number of high quality native plants. When we remove garlic mustard from an area mixed with desirable plants, we give those good plants a fighting chance this growing season.

While garlic mustard crowds out native woodland plants in the forest, it can be put to good use in the kitchen. Since it was in fact brought over by European settlers as a food ingredient, a few adventurous volunteers took home leaves and taproots of the offending plant to add to pesto, scallion cakes, and mashed potatoes. Pat Sherman tried garlic mustard ravioli with pesto sauce and said he would go easier on the garlic mustard taproot next time. It seems if you like garlic, youll love garlic mustard.

The introduction of biological controls, often leaf- and root-eating beetles, will hopefully prevent the need for pulling efforts in the near future. Several species of insects look promising, said Luke Skinner of the DNR invasive species program. But we need to be as certain as possible that the insects we introduce won‘t harm native plant species. Biocontrols could be available in the U.S. as early as next year.

Read more about Garlic Mustard in the fourth article of this newsletter, The Scourge of the Gorge.

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Volunteers put down roots in the Prairie Bowl

The River Gorge is host to a diversity of plant communities, provides significant habitat for migrating birds through the Twin Cities metropolitan area, and is a treasure to community residents. The area near 36th Street at West River Parkway includes the highest quality plant communities remaining in the River Gorge: an oak woodland undergoing restoration to oak savanna, a small area of oak forest, and a remnant mesic prairie — the Prairie Bowl.

In June Gorge Stewards helped to increase the species diversity within the Prairie Bowl. Led by Carolyn Carr of Ecological Strategies, volunteers prepared planting areas by pulling existing vegetation, then planted, mulched and watered more than 300 native grass and wildflower seedlings, introducing ten new plant species to the site. Volunteers will also provide any needed weeding this growing season so these new plants will have a chance to get established.

When restoring sites it is important to use native plants from local or regional sites with similar environmental conditions as the site being restored, so seedlings for this project were purchased from a local nursery propagating native species from seeds collected within the metropolitan area. Funding for the planting event was provided through the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative Commission on Minnesota Resources.

Please contact sue rich through our contact form if youd like to be involved in the ongoing maintenance of the habitat restoration efforts at the 36th Street site.

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Volunteers come out of their shell for woodland seed collection

The maple basswood forest in the river gorge is home to an array of woodland plants, and one of the few places in the city where people can experience the big woods. This forest plant community provides wildlife habitat, erosion control, and creates organic matter in the soil, but is also threatened by infestation of invasive plant species and suffers from the disturbances that accompany its use by an urban population.

These disturbances make seed dispersion, and therefore survival, more difficult for woodland plants, so on June 22 Gorge Stewards tried to provide extra help. Led by Carolyn Carr, and with permission to collect from the Minneapolis Park Board, a small group of volunteers collected mature seeds of wild ginger, bloodroot, and meadow rue. While swatting off mosquitoes, the volunteers cleaned and redistributed the seeds to other prepared areas that same evening. For more information about the plant structures and evolutionary characteristics that aid these plant populations in perpetuating themselves, see Woodland seed collection handout (PDF, 91 KB) compiled by Carolyn Carr.

Seed collection coordinated by Friends of the Mississippi River and Ecological Strategies, LLC with funding from the Mississippi Watershed Management Organization through a stewardship grant to Great River Greening.

Resources

• W. Cullina, 2000. New England Wildflower Societys Growing and Propagating Wildflowers of the United States and Canada. (A Frances Tenenbaum book). Houghton Mifflin Company. Boston and New York.
• Native Iowa Woodland Understory Restoration: A Guide to Collecting and Germinating Seeds. http://web.grinnell.edu/individuals/mottll/ Accessed 20 June 2005.
• Native Plants Propogation Protocol Database. University of Idaho. http://nativeplants.for.uidaho.edu/network/general.asp

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The scourge of the Gorge

Explore the beauty of the Mississippi River gorge and youll discover a rich forest floor that supports a striking array of spring wildflowers native to Minnesota: wild ginger, bloodroot, Jack-in-the-pulpit, Dutchmans breeches, and hepatica to name a few. Spring ephemerals and other woodland plants have long been threatened by enemies such as pollution, land development, and non-native earthworms. But these forest floor treasures are increasingly under siege by the herbaceous invasive garlic mustard (Alliaria petiolata).

Garlic mustard thrives in the same habitat as our native woodland plants and not only will eventually outcompete them by hoarding light, moisture, nutrients, soil and space. Left unchecked, garlic mustard will deprive us of the spring display of wildflowers. A less interesting forest is devastating in itself, but a monoculture of garlic mustard also reduces habitat for native wildlife species. Ecologists dont even know all the effects this loss of biodiversity will have on forest groundcover. In addition, garlic mustard is unfortunately a good companion plant to another marauder, the woody invasive shrub buckthorn (Rhamnus cathartica), since it seems to be unaffected by the soil chemistry alterations caused by buckthorn root systems.

A biennial herb, garlic mustard spends its first year as a rosette of leaves close to the ground. The following year, the plant flowers, produces seed, and dies by late June. Mature garlic mustard plants are stalked with triangular to heart-shaped, coarsely toothed leaves that give off an onion or garlic odor when crushed. Garlic mustard plant stalks in flower reach heights of 2 to 3 feet and produce clusters of small white flowers, each with four petals in the shape of a cross. Most of the leaves have faded away by June and the plants can be identified by dead stalks of dry, tan seed pods.

The first garlic mustard recorded growing in the United States was in 1868 on Long Island, New York. Most likely it was introduced by European settlers who grew it for food. The plant is present in 30 midwestern and northeastern states and has been added to the state Department of Agricultures Prohibited Noxious Weed list since woodland areas undergo a serious decline within a few years of an infestation. It grows particularly well near rivers and streams and in recent years has begun to flourish in areas along both Minnehaha Creek and the Mississippi River.

Several species of insects that appear to feed only on garlic mustard have been identified by Swiss and American biologists, but USDA approval of these biological controls could be a long way off. In the meantime, when garlic mustard invades an area it requires hard work and commitment to control it. Hand removal of plants before flowering is useful when care is taken to remove the plant and its roots. In late spring, flowering stems can be cut to the ground to prevent seed production. Flowering stalks left on site can still form seeds, so they should be bagged and removed from the site after cutting. As a last resort, chemical application can be used to treat large infestations during winter and early spring when native plants are dormant.

For more information about Minnesota invasives:

• Minnesota Department of Natural Resources: Invasive Species guide
• Global Invasive Species Team: Garlic Mustard photos and information
• Wisconsin Department of Natural Resources: Invasive species information
• Minnesota Department of Agriculture: Invasive species information