Energy Flow

  • It refers to the movement of energy through an ecosystem, from one organism to another. It is the process by which energy from the sun is converted into usable energy by plants through photosynthesis, and then transferred to other organisms through feeding relationships.
  • In an ecosystem, energy flows from producers (plants) to consumers (animals), and from one trophic level to another.
  • Trophic levels are different levels in a food chain or food web, which represent the position of an organism in the chain.
    • The first trophic level consists of primary producers (plants), which convert sunlight into usable energy through photosynthesis.
    • The second trophic level consists of herbivores, which eat the plants.
    • The third trophic level consists of carnivores, which eat the herbivores. There can be multiple levels in a food chain or web, with each level representing a different feeding relationship.
  • One must remember that the trophic level represents a functional level, not a species as such. A given species may occupy more than one trophic level in the same ecosystem at the same time;
    • for example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms.
  • Each trophic level has a certain mass of living material at a particular time called as the standing crop. The Standing crop is measured as the mass of living organisms (biomass) or the number in a unit area.
  • Energy flow is not 100% efficient, as energy is lost at each trophic level due to various factors such as respiration, movement, and waste. This means that the higher up an organism is in a food chain or web, the less energy it receives.
  • The number of trophic levels in the grazing food chain is restricted as the transfer of energy follows 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from the lower trophic level.
  • Overall, energy flow is an important process in ecosystems, as it determines the amount of energy available to support life and the interactions between organisms.

Except for the deep-sea hydro-thermal ecosystem, sun is the only source of energy for all ecosystems on Earth.

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