In 2008, volunteers began turning 6.25 acres of Illinois cornfield into prairie; 15 years later, 134 of 192 planted species remained | World News

PC: Wing-Chi Poon/ Wikipedia

A prairie planted on a former cornfield in Illinois has shown how a carefully planned restoration can develop over time. At Nachusa Grasslands, a 6.25-acre field was converted into reconstructed prairie as restoration began in 2008, using seed collected from 176 species suited to dry-mesic, mesic, and wet-mesic habitats. Additional seed was added by hand in 2009 and 2010, bringing the total to 192 species. As per the Grassland Restoration Network, the revisit found 134 of the 192 planted species, or 70%, growing there. The survey also recorded 30 native species that were not part of the original planting, while seven non-native species were found in scattered populations.

What did 15 years of prairie restoration reveal about Illinois farmland

The 15-year revisit found 134 of the 192 species included in the 2008-2010 seed mixes, which means 70% were still recorded in 2025. Stewards visited the site 15 times from April through late October to track the plants present throughout the growing season. They also found 30 native species that were not purposely included in the original seed mix, along with seven non-native species growing in small, scattered populations. The 2025 survey found 57 planted species with high conservation values, ranging from 8 to 10. Together, these findings indicate that the restored prairie retained many of its original plants while also developing a broader plant community over 15 years.

PC: Peterwchen/ Wikipedia

How did the prairie restoration begin in 2008

The restoration began after the corn was harvested in 2008. The field was first burned and harrowed, then the seed was divided into three mixes and planted in late November using a drop seeder, with multiple passes to spread it evenly. Each mix was chosen based on the field’s soil type and topography, covering dry-mesic, mesic, and wet-mesic areas. During the 2008 growing season, 225 pounds of bulk seed representing 176 species were collected for the planting. The bulk material included both seed and chaff, with seed accounting for about 40% of its weight.

Prescribed burns and weed control shaped the prairie’s development

The prairie continued to receive active management after the initial planting. Stewards collected additional seed during the 2009 and 2010 growing seasons and hand-overseeded 99.5 pounds in areas where native plants were particularly sparse. This brought the total number of species in the seed mixes to 192. Once overseeding was complete, prescribed burns were carried out about every other year as part of management of the larger unit. Stewards also monitored the prairie for birdsfoot trefoil, white sweet clover, and reed canary grass. All three became less common over time, although they still required ongoing monitoring and control. Together, additional seeding, prescribed fire and weed management supported the prairie’s development.

Which species established successfully across different prairie habitats

The 2025 survey found that planted species established at different rates across the prairie’s habitats. About 64% of the upland species were recorded, and 84% of facultative upland and facultative species were recorded. The figures were lower for wetter habitats, with 64% of facultative wet species and 53% of obligate wetland species found. Carex was among the least successful genera, with only three of the eight planted species recorded in 2025. The 30 native species that were not purposely planted also showed different habitat preferences. Thirteen were facultative upland species, while the rest included upland, facultative wet, and obligate wetland plants. These patterns reflected the varied conditions across the restored prairie.

Which factors affected species establishment over 15 years

The revisit also highlighted why some planted species were not recorded in 2025. The report notes that some may have failed to establish, while others may have lacked the conditions they needed to survive. Certain plants favour limestone soils, while others struggle in richer soil or depend on dry, wet, or sandy conditions. Some species may also emerge only in particular years or remain dormant in the soil as seeds.