TNC's Seven Sisters Prairie preserve in Minnesota.
Seven Sisters Prairie TNC's Seven Sisters Prairie preserve in Minnesota. © MinnesotaSeasons.com

Places We Protect

Minnesota

Seven Sisters Prairie

"The mountain" of Seven Sisters Prairie rises 190 feet above Lake Christina.

"The mountain" of Seven Sisters Prairie rises 190 feet above Lake Christina.  It offers visitors a panoramic view of the surrounding countryside and of Lake Christina--an important stop for many species of waterfowl during migration--and of the rolling topography of the Alexandria moraine (including the Seven knolls, or the "sisters").

Location
Otter Tail County (near Ashby)

Size
136 acres

Plants
The unusual plants of Seven Sisters Prairie have attracted botanists since 1893, when the first collections were made.  The dry and wet environments support a variety of plants, including a dozen plants at the eastern edge of their ranges, more commonly found in the Dakotas. All three grama grasses can be found at Seven Sisters: sideoats grama, blue grama, and hairy grama.  Prairie June grass, needle-and-thread grass, and thread-leaved sedge are also found at the site.

Animals
Lake Christina's average water depth of four feet allows a profusion of water plants to grow, and these nourish large flocks of canvasback ducks. Other  bird species that inhabit the preserve include the Baltimore oriole and the larksparrow.

Why the Conservancy Selected This Site  
This acquisition was made to protect the gravel prairie that occurs on this site. 

What the Conservancy Has Done/Is Doing
The Nature Conservancy purchased the land from the Richard A. Trow estate in July 1978 to protect the gravel prairie.  A wildfire burned the entire preserve in 1980, and a second wildfire burned part of it in 1982.  Grazing ended and fire was reintroduced as a management tool at the preserve when the Conservancy acquired it.  Controlled fires reduce plant debris accumulated from previous growing seasons and suppress invasion by woody species. 

Measures to control invasive European buckthorn and prickly ash are especially important to the health of the preserve.  Erosion threatens a population of broom-rape which grows in and around the gully.  The rim of the gravel pit is especially vulnurable to human erosion and visitors are asked to avoid this area.

For more information on visiting this and other Minnesota preserves, check out our Preserve Visitation Guidelines.