Yellowstone’s free moving large bison herds provide a glimpse of their past ecosystem function

While momentum is building to restore bison across North America, most efforts focus on small, managed herds, leaving it unclear how large, migrating bison shape landscapes and whether their effects enhance or degrade ecosystems. We assessed carbon and nitrogen dynamics across the migratory landscape of bison in Yellowstone, one of the last large migratory populations. Bison stabilized net aboveground production while accelerating nitrogen turnover, increasing aboveground nitrogen pools while carbon pools remained stable, which improved landscape nutritional quality. Effects were strongest in wet, nutrient-rich habitats that received higher bison densities and grazing than recommended in rangeland management, while soil and plant conditions suggested landscape resilience. Restoration should embrace heterogeneity in densities and effects across habitats and spatial scales beyond those guiding most current recovery efforts.