How is energy flow in an ecosystem characterized?

Energy flow in an ecosystem is characterized as one way due to the principle of energy transfer in food chains and food webs. When energy enters an ecosystem, typically through sunlight, it is captured by primary producers such as plants via photosynthesis. These producers convert solar energy into chemical energy, which is then utilized by herbivores (primary consumers) that eat the plants. This process continues up the trophic levels to carnivores (secondary and tertiary consumers).

As energy moves through these levels, it diminishes due to metabolic processes and heat loss, meaning not all energy is passed on to the next trophic level. In fact, approximately only 10% of the energy is transferred from one level to the next, while the rest is lost as heat. This linear progression reinforces the idea that energy moves in a one-way flow—entering from the sun, transferred through organisms, and eventually flowing out of the ecosystem as heat when organisms die and decompose. This understanding highlights the importance of energy conservation in ecological studies and the functioning of ecosystems, setting it apart as a fundamental ecological principle.