Yellowstone Bison Herds Enhance Grassland Resilience, Nutrient Cycling

Recent research led by ecologists including Chris Geremia, Bill Hamilton, and Jerod Merkle reveals that the restoration of large, free-roaming bison herds in Yellowstone National Park significantly enhances ecosystem health and nutrient cycling on a landscape scale. Tracking bison migrations and grazing behaviors from 2015 to 2022, the studies found that these animals boost nitrogen cycling, increase soil microbial density, and improve plant nutritional quality by up to 150%, particularly in nutrient-rich river valleys. Despite intense grazing that may appear detrimental, bison grazing stabilizes plant production and promotes ecosystem resilience, highlighting the importance of large, migrating herds rather than small, managed populations. The bison population in Yellowstone, now around 5,000 animals, migrates approximately 1,000 miles annually, demonstrating the ecological power of their natural movements. This body of work challenges previous assumptions about grazing impacts and underscores the critical role of migratory megafauna in maintaining grassland ecosystems. These findings support growing momentum for bison restoration efforts focused on enabling natural migration to fully realize their ecological benefits.