The 10% rule is a key principle in ecology that states that only 10% of energy is transferred from one trophic level to the next.

Energy transfer among trophic levels is a crucial concept in the study of ecosystems. According to the 10% rule, as energy moves up the food chain, only 10% of the energy from one level is passed on to the next. This indicates that the energy available to each successive trophic level diminishes significantly. For instance, if a plant contains $10,000$ joules of energy, only $1,000$ joules will be available to the herbivore that consumes it. The remaining energy is lost as heat or utilized by the plant for its own metabolic processes.

The implications of the 10% rule are significant for the structure and function of ecosystems. It elucidates why food chains and food webs are typically limited to a few trophic levels; there simply isn’t enough energy to sustain a large number of organisms at higher levels. Additionally, it underscores the critical role of primary producers, such as plants, in sustaining higher trophic levels. Without a sufficient supply of energy from these primary producers, higher trophic levels would struggle to survive.

In summary, the 10% rule is essential for understanding energy transfer in trophic levels. It emphasizes the importance of energy conservation and highlights the vital role of primary producers in maintaining the balance of ecosystems.