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3M Cottage Grove facility — Oak Savanna and prairie restoration

[Photo: Prairie savanna at 3M’s Cottage Grove facility.]

A view of the prairie savanna at 3M’s Cottage Grove facility.

In 2003, the 3M Cottage Grove facility hired Friends of the Missssippi River to complete a natural resource management plan for some of the land surrounding the facility. The following year, restoration work based on the recommendations of the plan began.

The 3M Cottage Grove facility, located near the Mississippi River, includes an extensive buffer area of fields and natural areas, some of which retain high quality native plant communities. One of those areas, a roughly 26-acre oak savanna/prairie remnant located along the railroad tracks on the east side of the site, was identified by the Minnesota Department of Natural Resources as an area of high biological integrity. When FMR completed the natural resource management plan for a portion of the 3M property in 2003, the prairie/savanna was identified as the highest quality natural area. Initial restoration efforts have focused on that area, beginning in 2004.

[Photo: Large-flowered Penstemon.]

Large-flowered Penstemon, one of the colorful native species at the site.

The sand-gravel dry prairie is located on south-facing slopes, bisected east-west by a railroad track and dissected north-south by shallow ravines and swales. The site has very good plant diversity with about 90 native grasses and prairie flowers. Colorful species include three prairie clovers (purple, white, and silky), narrow-leaved puccoon, large-flowered penstemon, prairie larkspur, lead plant, whorled milkweed, flowering spurge and prairie smoke. Some of the less common species found included golden corydalis and showy orchis (in a woodland).

[Photo: Leafy spurge detail]

Leafy spurge is one of the invasives at the 3M site that we are working to control.

The prairie, unfortunately, also has an infestation of leafy spurge (Euphorbia esula), a very invasive plant that spreads rapidly and displaces most natives. FMR has been working with 3M to control the invasive habits of the species. Releasing biological control agents is the most likely solution. For leafy spurge, the leafy spurge beetle (Aphthona lacertosa), which feed exclusively on leafy spurge, often provides good control. The beetles will not eliminate the species, but may reduce it to a level where native species can co-exist with it.

[Photo: View of the leafy spurge infestation affecting one part of the site.]

The yellow swath of color on this hillside is an infestation of the exotic invasive, leafy spurge.

A massive amount of woody invasive species has also been removed from the prairie and adjacent woodland. The non-native shrub tartarian honeysuckle was most abundant, with lesser amounts of common buckthorn.

A prescribed burn on May 5, 2006, was likely the first fire on the site in many decades. Prairie and savanna are fire-dependent communities, requiring periodic fire to reduce tree and shrub cover and to stimulate growth of prairie species. In the present-day landscape, fire also reduces non-native species, many of which are not fire-adapted.

[Photo: 3M employees collecting prairie seed.]

3M employees collecting prairie seed. Employee volunteers play an active role in the restoration work at the site.

FMR also works with 3M employee volunteers to collect prairie seed, remove exotic plants, and learn about birds and prairie plants on the site.

More Photos

[Photo: Prairie larkspur]

Prairie larkspur. This and all the other pictures on this page were taken at the 3M prairie savanna area.

[Photo: Showy orchis]

Showy orchis

[Photo: Silky prairie clover]

Silky prairie clover

Species list

3M_plant_species (72 KB PDF) — A list of plant species native to dry sand-gravel prairie/savanna areas such as the 3M restoration site. Read more…