Bison Grazing and Biodiversity?

bison eat gr. by then eating gr it put more manuer out on the field. bison are member of cow family they Borgnine from goat / deer & other hoofed ancestor. but bison were brought to Americas by early native-American crossing the Bering strait. before it got there only shrub/thorn-bushes & other thick plant grew in north-America. over -time they adapted to colder temp. then before when they were living in Asia. they came here as a breed of oxen. over 2k they adapted fur coats & sharper hot to keep away predators wolf, coyote, jackal, fennecs, the early Asians let them graze. they spread over 4k-mile of land. & soon after they arrived. gres, weeds, yeast & other plants started sprouting over the barren-land.