biogeochemical cycle

In geology, a cycle of biological (living) matter as it circulates through geological environments to form an ecosystem. A forest ecosystem, for example, is comprised of plants and animals that rely on elements in soil and water to live. A biogeochemical cycle is the process of exchange between living (e.g., trees) and nonliving (e.g., soil) parts of the ecosystem through a series of chemical reactions at the cellular level.