Concepts of Ecosystem and Agroecosystems:

• The concept of ecosystem was first put forth by A. G. Tansley (1935).
• According to E. P. Odum, the ecosystem is the basic unit of organisms and their environment interacting with each other and with their own components.
• All the ecosystems of the earth are connected to one another, e.g., river ecosystem is connected with the ecosystem of oceans, and a small ecosystem of dead logs in a part of large ecosystem of a forest.
• A complete self-sufficient ecosystem is rarely found in nature but situations approaching self-sufficiency may occur.