Restoring America's Prairie: The Role of Bison in Conservation Efforts

Cultural, ecological, and economic benefits of tribal bison restoration

How Bison Are Restoring American’s prairie

The role of Bison in conservation efforts

American Prairie is a nonprofit conservation group that aims to restore a vast shortgrass prairie in Montana by reintroducing herds of bison. Bison, also known as buffalo, once played a crucial ecological role in creating a cascade of environmental conditions that benefited other species in the complex ecological web. However, farming and livestock grazing have eliminated or reduced many of these species, and intact grasslands are now endangered. The reserve has set a goal to settle 6,000 bison on 500,000 contiguous acres, with the hope that one day, bison in reservations, American Prairie, and nearby wildlife refuges in the United States and Canada may become one vast herd, roaming across about 3 million acres.

The tallgrass prairie is a critically endangered ecosystem in the Midwest of North America. In Illinois, 99% of the prairie has been lost due to development and farming. The Nature Conservancy has been working to restore Nachusa Grasslands, an area of prairie and former prairie land in Illinois, since 1986. In 2016, the group reintroduced 110 bison to a third of the 3,500-acre plot. The reasoning behind this is simple: prairies have co-evolved with bison. It is an ecosystem that depends on grazing disturbance, so conservationists have brought back the dominant grazer into the system.

Bison are useful grazers because they are relatively fussy eaters and prefer to eat grass over anything else. This makes them ideal for former prairie land where native wildflowers have often given way to grasses. By eating the grass, bison create space for wildflowers and the sunlight they need to grow. But bison do more for the prairie than just cut the grass. Bison are ecosystem engineers because they have outsized effects that impact how the ecosystem is shaped.

One example of their impact is their wallowing behavior. Bison create huge depressions in the ground without any plants. These depressions can provide a habitat for ground-nesting birds and insects, and spring rains can fill the wallows with water, creating temporary ponds that are home to frogs. Another way bison shape the ecosystem is by improving soil health. Their waste acts as a natural fertilizer, providing nutrients that help native plants grow, which in turn attracts insects and other animals.

Agriculture has also taken a huge toll on the prairies. “It’s being plowed up fast and mismanaged for cattle,” said Curt Freese, a wildlife biologist and one of the founders of American Prairie. Nearly a million acres in the eight-county region around the reserve have been converted to cropland in recent years, Dr. Freese said. This has resulted in a significant reduction in the number of species that once thrived on the prairies.

How Bison Are Saving America’s, Lost Prairie

The reserve has encountered several challenges that have pushed its goal well into the future. Land costs, politics, and other complications have made the creation of a fully functioning wild prairie with herds of bison thundering across the landscape difficult. Researchers and experts have since become more realistic, understanding that the original timetable to create such a vast grassland is just not feasible. A full-blown prairie ecosystem is still decades away, and it won’t be cheap: Dr. Freese estimates it is likely to cost several hundred million dollars.

Recent studies have demonstrated some of the important ecological effects that bison have on grasslands. A long-term comparative study of bison and cattle on tallgrass prairie in Kansas showed that over about 30 years on land grazed by bison, the richness of native plant species doubled compared with places where cattle grazed, and the presence of bison made the prairie ecosystem more resilient to drought.

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