The bison population has been restored in Yellowstone National Park — and it’s reawakening the ecosystem.

Researchers have found that a herd of migratory bison leaves more nutrient-rich plants in its wake as the creatures move around the park each year. Scientists analyzed the soil and plant diversity in the herd’s migration corridor and discovered that free-roaming bison are crucial to maintaining a healthy and diverse plant community.

Conservationists have long debated whether allowing bison to roam freely could lead to overgrazing issues. However, this new research confirms traditional Indigenous ecological knowledge about the benefit of bison in North American ecosystems.