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Unit 1: Basic Ecological Concepts and Principles Related to Agricultural Systems

Most of the energy in natural ecosystems is lost as heat as it flows from one level to the next, and what is stored as plant biomass usually accumulates within the ecosystem. In an agroecosystem, much of the energy that is stored or transferred from organism to organism is ultimately lost from the system in the form of a marketable agricultural product. Also note that in the United States and other countries we often add energy to agricultural systems in forms other than sunlight, such as fossil fuel energy used to manufacture chemical inputs, to power farm machinery, and for processing and transporting agricultural products.

For a more detailed explanation of trophic structure and energy relationships in ecosystems, read the following article:
Trophic Levels. Dave McShaffrey. Marietta College, Marietta, Ohio. 1995.