Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.
Flow of energy in an ecosystem can be described as follows:
• In the terrestrial environment, green plants utilize about 1% of solar energy that is falling on their leaves. This energy is converted into organic matter by plants.
• But a great portion of energy is utilized by the plants for their own metabolic needs. Just 10% of the total energy is available for primary consumers.
• Similarly, out of total energy consumed by an organism at a particular trophic level, just 10% is available for the organism at next trophic level.
• As a result, a negligible amount of energy is available for the organisms at the topmost trophic level. Due to this, an ecosystem contains at the most four trophic levels.
• There are more organisms at lower trophic than at top trophic levels. This is the general rule but some exceptions may be present.
• The food chain becomes quite complex in real world: making the food web because most of the carnivores eat many organisms.
The flow of energy is unidirectional because of two reasons. Energy always flows from the prey to the predator and not the other way round. Less energy is available as we move towards higher trophic levels.
