Why is only 10% of energy transferred from one tropic level to the next?
The transfer of energy between trophic levels is governed by the laws of thermodynamics, particularly the second law. This law states that energy conversions are never 100% efficient, and there is always some loss of energy in the form of heat during each conversion.
In ecological systems, energy is primarily transferred through the consumption of organic matter. When an organism consumes food, it only converts a portion of that energy into biomass (its own body mass). The rest of the energy is used for metabolic processes such as respiration, excretion, and movement, which result in the release of heat energy.
As energy is passed from one trophic level to the next, each organism in the food chain similarly uses only a portion of the energy it consumes for growth and other life processes. This process of energy loss continues at each trophic level, resulting in a progressive reduction in the amount of energy available for transfer.
Additionally, organisms at higher trophic levels are often larger and have higher metabolic rates than those at lower trophic levels, meaning they require more energy to sustain themselves. This further reduces the energy available for transfer to the next trophic level.
Overall, the 10% rule reflects the inefficiency of energy transfer between trophic levels, as dictated by the second law of thermodynamics and the energy demands of organisms at each level.