Plants receive the sun’s energy and use it to convert inorganic compounds into rich organic compounds. Therefore, biological activities in an ecosystem require energy from the sun. The received solar energy is transformed into chemical energy, which is bound in glucose form as potential energy during the process of photosynthesis.
Photosynthesis marks the beginning of a chain of energy conversions in an ecosystem. A number of animals feed on the photosynthesis products, such as when goats eat shrubs, worms eat grass, and rats eat grains. When animals feed on these plant products, food energy and organic compounds are transferred from the plants to the animals. The animals may in turn be eaten by other animals, further transferring energy and organic compounds from one animal to another -- for instance, when humans eat sheep, birds feed on worms and lions eat zebras. This chain of energy transformation from one species to another can continue for several cycles, but it eventually ends when the dead animals decompose, becoming nutrition for fungi and bacteria.
Fungi and bacteria are decomposers in energy transformation in an ecosystem. They are responsible for breaking down the complex organic compounds into simple nutrients. Decomposers are important in the ecosystem because they break down dead materials. There are different types of decomposer organisms, which are responsible for returning simpler nutrients to the soil to be used by plants -- and so the energy transformation cycle continues.
Flow of Energy
Energy accumulated by the primary producers is transferred via the food chain through different trophic levels, a phenomenon called energy flow. The pathway of energy flow moves from primary producers to primary consumers to secondary consumers and finally to decomposers. Only approximately 10 percent of the available energy moves from one trophic level to the next.
Principles of Energy Flow
Energy flow through a food chain occurs as a result of two laws of thermodynamics, which are applied to the ecosystem. The first law of thermodynamics states that processes involving energy transformation will not occur spontaneously unless there is degradation of energy from a non-random form to a random form. This law requires that in an ecosystem each energy transfer should be accompanied by dispersion of energy into respiration or unavailable heat. The second law of thermodynamics is the law of conservation of energy, which states that energy may be transformed from one source to another but is neither created nor destroyed. If an increase or decrease occurs in the internal energy (E) of an ecosystem, work (W) is done, and heat (Q) changes.