Impact of Bison on the Environment
Grazing Patterns & the Effect on Grasslands
Bison, whether they're in the wild or on private ranches, are undomesticated animals. The natural instinct of bison is to "selectively graze". This means they graze on dominant grasses - avoiding forbs and woody species - resulting in patchy distribution which allows for increased plant species and diversity by allowing forbs to flourish. Forbs, such as clover provide different nutrients to the soils, allowing them to flourish ensures the diversity of the environment.
Bison are always moving, they don't stay in one place for very long. So, rather than eating the grasses down in one place, bison graze on the ground cover that would "choke" nutrients from the ground. They naturally remove excessive growth, thus allowing more room for healthy plants and grasses to grow.
Additionally, photosynthesis rates increase in the plant life where bison graze, due to increased light availability and reduced water stress because of their selective grazing habits.
Ranchers of domesticated animals, such as cattle, have created "rotational grazing patterns" which try to replicate the natural grazing habits of bison to gain some of the same benefits to their land.
(This is a photo of a land imprinter. It is a machine created to mimic the grazing of bison by creating fake hoof prints for water retention.)
Physical Impact on the Land
As stated earlier, bison are always moving, their hoof prints can bury seeds, helping the growth of grasslands, but the pockets their hoof prints create are able to catch moisture and rain, aiding in moisture retention and the growth of plants. Small ponds and water holes have actually even been created by bison wallows (bison rolling on the ground, creating a shallow depression) which also aide in moisture retention.
And since the natural instinct of bison is to always be moving and not hang in the same place for too long, bison do not "hang around the watering hole" like domesticated animals would. Nature has adapted their behavior to avoid lingering around watering holes - where predators notoriously wait for their prey. Since they take their water and move one, bison do not damage the banks of the water through over use.
Wide Open Spaces
Bison ranchers give their herds plenty of room to roam and grow, allowing the animals to follow their natural instincts and grazing patterns, keeping bison wild and allowing the environment to reap the natural benefits of the behavior of bison.