what america lost when it lost the bison

https://www.theatlantic.com/science/archive/2019/11/how-bison-create-spring/602176/

When Geremia’s team looked at parts of Yellowstone where bison numbers have fluctuated, it found that the green wave grew in intensity and crested over a longer period as the herds grew larger. The bison engineer and intensify the spring. And astonishingly, they had a stronger influence on the timing of plant growth than weather and other environmental variables. They’re equivalent to a force of nature.