Settlers reduced the numbers of large grazers, such as caribou and bison. Grazers were a very important part of maintaining the prairie. The settlers suppressed fire, one of the most important parts of maintaining a prairie. Prairie restoration protects the environment. It increases the abundance of native plants, and therefore creates habitats for native animals and insects.
Prairies are stable ecosystems.
No fertilizer or herbicide is needed for maintenance. Prairies absorb a lot of rain, reducing erosion and runoff. Prairies increase ecological diversity.