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Iowa

The Loess Hills


Fine particles of wind blown silt, known as loess, created the Loess Hills as glaciers retreated north at the end of the last Ice Age. Today, the 650,000-acre Loess Hills landscape rises 200 feet above the Missouri River valley and is recognized for its unusually deep deposits of loess. Only one location in China has deeper and more extensive loess deposits.

The steep, rugged terrain here supports the best examples of loess prairie in the five-state Central Tallgrass Prairie region. Iowa’s largest surviving prairies are found in the Loess Hills, and the Conservancy’s Broken Kettle Grasslands Preserve contains the largest contiguous native prairie in the state. The Conservancy and partners have protected more than 7,000 acres at Broken Kettle, but our long-term conservation goal is much more ambitious. With the help of partners and local landowners, the Conservancy hopes to preserve more than 100,000 acres in the Loess Hills through acquisition and conservation easements, and to maintain healthy ecological systems within a sustainable, working agricultural landscape. The Conservancy also is working with partners on compatible development, seeking ways to improve pastures and prairies for livestock producers, and native seed harvesting.

Conservation in Action

Wildfires, which periodically swept through the area, and grazing bison and elk once helped keep Iowa’s prairies healthy. Today, however, the natural role of fire has been drastically altered. By eliminating fire as a natural disturbance, brush and trees are infiltrating, shading out the fire-tolerant native prairie and oak woodlands. This alteration – along with an increased residential development, incompatible land use and fill dirt mining – threatens to harm the area’s fragile natural communities. Loess Hills prairies are home to many species typical of the Western Great Plains, including yucca, cowboy’s delight and prairie rattlesnakes. Migrating raptors follow the ridgelines. The upland sandpiper, a declining species, lives in the grasslands in the northern hills. Native plants include side-oats grama, skeleton weed and prairie moonwort, a rare fern discovered here in 1984. Many other varieties of prairie grasses and wildflowers abound.

The Conservancy is using science-based conservation in the Loess Hills to restore and maintain healthy habitats for prairie plants and animals. For example, about 4,000 acres are blackened by controlled fire each year. Scientific analysis has revealed, however, that to keep this prairie healthy five times that amount, or 20,000 acres, needs to be burned each year.

Cattle producers are important partners, as the Conservancy seeks to develop sustainable grazing practices that mimic historic grazing patterns. As part of that initiative, the Conservancy plans to reintroduce bison at Broken Kettle Grasslands. With the help of partners and local landowners, more then 100,000 acres in the Loess Hills will be protected through acquisition and conservation easements.

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