Bison and Prairie Health

By Tara Kelly, Director of Ecological Restoration

For the last three summers we have hosted herds of bison on the Belwin Conservancy’s preserve. The goals of this reintroduction were numerous and lofty. For starters, we hoped to inspire the community with this iconic North American mammal. Mission accomplished. The Bison Release is more successful than we ever imagined and visitation to our preserve has skyrocketed.

We also wanted to demonstrate that land could be in conservation and produce a marketable product. This too has been a great success. At the end of each summer, the bison that we hosted have grown tremendously and are in great health. Our partners at NorthStar Bison can’t keep up the demand for grass-fed bison meat and are looking for more areas to graze their animals.

Most importantly in my mind, we intended to use this keystone animal to increase the health of our prairies. Restorations, at best, are only an approximation of the prairies that were here prior to European settlement. Having the bison on them adds one more piece in the restoration puzzle.

A healthy prairie is a balance of grasses and flowers. This diversity means more stability and higher quality habitat for a whole host of species. Some areas of our prairies lack this diversity and the plan was to use the grazing patterns of the bison to improve it. Bison prefer to graze on grasses that dominate our prairie in some areas. Our hypothesis is that if the bison grazed these grasses down enough to keep them in check, flowers would have the opportunity to become established in the tall grass stands and balance could be restored.

For the past two growing seasons, after prescribed burning in the springtime we seeded the burn area with native flower seed. The bison were then allowed to graze the entire prairie from mid-June through mid-October.

In August of each year, members of the Conservation Corps of Minnesota and Belwin Conservancy staff visited random study plots in the prairie to discern the patterns in bison grazing and the prairie’s response to this cycle of burning, seeding and grazing.

Overall, the bison grazed in a majority of our plots (85% in 2009 and 91% in 2010). They also grazed a substantial portion of each plot they visited (34% in 2009 and 26% in 2010) and strongly favored the native prairie grasses. Most importantly, we found that grazing, in combination with burning and seeding, has been successful in establishing native flowers into the prairie. The areas that were seeded just two years ago already had significantly more native flowers than areas that were not seeded. For example, just in the last year, the amount of native flowers increased from 6% to 35%!

All in all, our partnership with NorthStar Bison has been rewarding and we can’t wait to have the bison back on our prairies this spring. Please join us for the annual Bison Release on June 11th. Check out our website for more details, www.belwin.org.