Abstract

Tallgrass prairie is one of the most imperiled ecosystems on Earth. A 2004 estimate indicated that only 2.4 percent of the original northern tallgrass prairie remained in the United States. If tallgrass prairie and the species dependent on it are to survive, management must include restoration of cropland and degraded prairies, in addition to preservation of the few remaining fragments. Despite the importance of restoration and its long history (the first tallgrass prairie restoration was started in 1935 at Curtis Prairie in Wisconsin), few studies have been undertaken with the goal of refining restoration practice. This fact sheet contains the results of one such study, started in 2005, in which we compared three seeding methods (dormant-season broadcast, growing-season broadcast, and growing-season drill) fully crossed with low (10-), medium (20-), and high (34-species) seed mixes replicated 12 times on each of 9 former agricultural fields in Minnesota and Iowa. Plots were 12.2 x 12.2 meters (m) and occupied about 1.6 hectares (ha) (4 acres) of each field. A “successful” restoration is one in which cover and richness of planted species is maximized and cover of exotic and invasive species, especially the noxious weed Canada thistle (Cirsium arvense), is minimized. Details of the planting methods can be located in Larson and others (2011).

First posted July 26, 2013