A keystone species is the core species in an environment. This will be a species which provides a lot of the biological and zoological processes of that environment, for example, a rodent species will typically be a keystone species, both as a forager affecting the environment and as a prey species. Keystone species typically create the environmental food chain, and in some cases controlling the ecology. A keystone plant species will create habitat, which underpins the functions of all other species in that environment.