There is no natural habitat on earth known that is inhabited just by a single species. For any species, the minimal requirement is one more species on which it can feed. Even a plant species, which makes its own food, cannot survive alone and needs soil microbes to break down the organic matter in soil and return the inorganic nutrients for absorption. It is obvious that in nature, animals, plants, and microbes do not and cannot live in isolation but interact in various ways to form a biological community.