Abstract
The ecosystem concept encompasses relationships among different species while also including non-living components. The term “ecosystem” was first used by Tansley, in 1935, but the concept was described in the late 19th Century. One major usage of the term, advanced by E.P. Odum, has been the stock-and-flow conceptualization, which explicitly analyzes the movement of material or energy through various ecosystem compartments. A structural conceptualization of the term has also become common, with the term “ecosystem” referring to a local instance of a biome. The ecosystem concept was originally developed for natural systems but can also be applied to human-dominated environments.