→ Sun is the only source of energy for all ecosystems on Earth, except for the deep sea hydro-thermal ecosystem.
→ Of the incident solar radiation less than 50 per cent of it is photosynthetically active radiation (PAR).
→ We know that plants and photosynthetic bacteria (autotrophs), fix sun's radiant energy to make food from simple inorganic materials.
→ Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world.
→ So, it is very important to know how the solar energy captured by plants flows through different organisms of an ecosystem.
→ All organisms are dependent for their food on producers, either directly or indirectly.
→ The flow of energy from the sun to producers and then to consumer is unidirectional.