How does energy flow in an ecosystem?

Energy flow in an ecosystem primarily occurs in a one-way direction, moving from producers to consumers. The sun serves as the ultimate source of energy for most ecosystems, as it provides the light necessary for photosynthesis, enabling plants to convert solar energy into chemical energy. This energy is then passed along the food chain as organisms consume one another: herbivores eat plants, and carnivores eat herbivores.

This linear movement of energy highlights that it cannot be recycled in the same way nutrients can be. Once energy is transferred to one trophic level, it is not returned to the previous level; instead, a significant portion is lost as heat at each step of transfer. Thus, energy does not flow back and forth, nor does it create a circular flow, as energy diminishes at each trophic level, requiring a continuous input (such as sunlight) to sustain the ecosystem. Hence, a one-way direction effectively describes how energy flows through an ecosystem, emphasizing its linear and non-recycling nature.