Energy flow (ecology)

In ecology, energy flow, also called the calorific flow, refers to the flow of energy through a food chain, and is the focus of study in ecological energetics. In an ecosystem, ecologists seek to quantify the relative importance of different component species and feeding relationships.

A general energy flow scenario follows:

The energy is passed on from trophic level to trophic level and each time about 90% of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as incompletely digested food (egesta). Therefore, primary consumers get about 10% of the energy produced by autotrophs, while secondary consumers get 1% and tertiary consumers get 0.1%. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. This loss of energy at each level limits typical food chains to only four to six links.

Ecological energetics appears to have grown out of the Age of Enlightenment and the concerns of the Physiocrats. It began in the works of Sergei Podolinksy in the late 1800s, and subsequently was developed by the Soviet ecologist Vladmir Stanchinsky, the Austro-American Alfred J. Lotka, and American limnologists, Raymond Lindeman and G. Evelyn Hutchinson. It underwent substantial development by Howard T. Odum and was applied by systems ecologists, and radiation ecologists.

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