white lotus in pond

Flow of Energy in an Ecosystem


Energy is the basis of the whole biosphere.

Both the living beings and the non-livings contain energy. That energy is hidden in between atoms and molecules.

As per the First Law of Thermodynamics “Energy can neither be created nor can it be destroyed”. It can only be destroyed from one form to the other.

Sun is the only source of energy in the biosphere. Every living being can get its share of energy through food only and the energy is directly or indirectly obtained from green plants only.

Only green plants are able to utilize the energy of sun. They absorb solar energy during the process of Photosynthesis and convert this energy into chemical energy which is retained in the form of bond energy between atoms and molecules. Since only plants can utilize and transform the solar energy in the ecosystem they are called as Transducers.

Only 1% of the solar energy can be utilized by green plants. This energy gets stored between molecules of food they synthesize. Some part of this energy is used up in the metabolic processes of plants.

The remaining energy goes to consumers when they feed on plants. Consumers too utilize some energy in their metabolic processes. Under these conditions some energy escapes away in the form of their body heat and some energy is wasted through excretory matter from their bodies. The rest of the energy goes into the atmosphere when top consumer dies and its body is decomposed. Now we can conclude that –

(i) Energy flows in the acyclic manner in the ecosystem.

(2) Some energy is wasted at each trophic level of the food-chain

Lindeman (1942) reported that the energy available in each step of the food-chain remains 10% of the energy available at the earlier step. It means if a vegetarian animal consumes 100 kg of grass the energy that it can use will be equal to the energy contained in 10 kg of grass only. This is called as Lindeman’s 10% Law.

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