“Bison have made a remarkable comeback in Yellowstone National Park, going from fewer than two dozen animals at the turn of the last century to roughly 5,000 today. Their return, a study finds, has had a remarkable impact on grasslands in the region.

The Yellowstone bison travel around 1,000 miles each year, moving back and forth along a 50-mile route through verdant river valleys. As bison graze, they also churn the earth and deposit manure, helping to boost microbes in the soil. These microbes, in turn, nourish grasses with nitrogen from decaying plants.

Comparing grazed and ungrazed areas, scientists were able to quantify the impact on grasslands. They found that, even where bison grazed heavily, grasses grew as much as they would have in the absence of grazing, and, importantly, were 150 percent more nutritious.”

From Yale Environment 360.