Description & Significance

Foster Hill savanna is located an in area of approximately 19 acres. It was first identified by the Wisconsin Department of Natural Resources (WIDNR) Bureau of Endangered Resources plant survey team as an area with significant rare plant populations. It was identified as an official project area by the WIDNR in 1987. The project was proposed but not implemented, so parts of the property were subdivided and houses built. Fortunately, most of the rare plant habitat survived on steep slopes at the back of each private parcel. Most of the site has been actively managed by TPE since 1999.

CONSERVATION SIGNIFICANCE

Foster Hill is a large complex of oak savanna and dry prairie. The bedrock outcroppings on Foster Hill belong to the Prairie Du Chien group, a series of dolostones, sandy dolostones, and sandstone formed earlier in the Ordovician period in an intertidal or shallow marine environment. The bedrock is highly fractured and honeycombed with solution cavities. This bedrock is covered on the bluff top by glacial drift. The drift consists of a poorly exposed mixture of outwash sand and gravel and wind-blown loess. The outwash was most likely from the Superior Lobe. Colluvium of varying thickness occurs on the steeper slopes.

This site is significant in that it is located along the Kinnickinnic River and abuts the former Lake Louise in an area with several hundred acres of protected land surrounding the site. This coupled with healthy rare plant populations and ease of management makes long-term success and sustainability of this project more likely.

Natural History

Much of this site was formerly owned by the Johnson family who used it to pasture cows and horses. Lower fields were once plowed for a hemp crop but soon abandoned due to poor soil quality. The horse pasture was seeded to smooth brome but many native plants, including some threatened species have returned in the brome sod.

The hillsides were only lightly grazed and hold significant populations of prairie savanna.

The Prairie Enthusiasts St. Croix Valley Chapter has been managing portions of this site since 1999. Much of the red cedar and brush that covered the hills has been removed and a controlled burn program has been initiated.