balance of nature

In ecology, the idea that there is an inherent equilibrium in most ecosystems, with plants and animals interacting so as to produce a stable, continuing system of life on Earth. The activities of human beings can, and frequently do, disrupt the balance of nature.

In general, organisms in the ecosystem are adapted to each other - for example, waste products produced by one species are used by another, and resources used by some are replenished by others; the oxygen needed by animals is produced by plants while the waste product of animal respiration, carbon dioxide, is used by plants as a raw material in photosynthesis. The nitrogen cycle, the water cycle, and the control of animal populations by natural predators are other examples.

The idea of a balance of nature is also expressed in the Gaia hypothesis, which likens the Earth to a living organism, constantly adjusting itself to circumstances so as to increase its chances of survival.