Why is only 10% of energy transferred from one trophic level to the next?
The transfer of energy between trophic levels in an ecosystem is governed by the laws of thermodynamics, particularly the second law of thermodynamics, which states that energy will always flow from areas of higher energy to areas of lower energy, resulting in a decrease in the amount of available energy.
The efficiency of energy transfer between trophic levels can be influenced by various factors, including metabolic efficiency, organism behavior, and energy lost through waste production (such as heat and undigested materials). These factors contribute to the overall energy loss during each transfer.
In the process of energy transfer, an organism at one trophic level (such as a herbivore) consumes energy-rich organic matter (plants) from the previous level. However, not all of this energy is absorbed and assimilated by the consuming organism. Some energy is lost as heat during metabolic processes, some is used for the organism's growth and maintenance, and some is excreted as waste. Consequently, only a fraction (typically around 10%) of the energy from one trophic level is transferred to the next.
This energy loss is a fundamental aspect of the functioning of ecosystems, as it limits the number of trophic levels that can be sustained and the size of populations within those levels. It also explains why food webs generally have a pyramid shape, with fewer individuals and biomass at higher trophic levels compared to lower levels.