ENERGY FLOW IN ECOSYSTEM
v All organisms must obtain a supply of energy and nutrients from their environment in order to survive.
v The transformations of energy in an ecosystem begin first with the input of energy from the sun.
v Because, it is the first step in the production of energy for living things, it is called “Primary production”.
v Photosynthesis -- Chemical reaction where green plants use water & carbon dioxide to store the sun’s energy in glucose.
v ENERGY is stored in glucose.
v Glucose is stored as starch in plants
v The majority of autotrophs are photoautotrophs that harness the energy of the sun and pass some of this energy onto consumers through feeding pathways.
v The energy contained within producers and consumers is ultimately passed to the decomposers that are responsible for the constant recycling of nutrients.
v Thus, there is a one-way flow of energy through the biotic community and a cycling of nutrients between the biotic and abiotic components of the ecosystem
v Energy flow cannot occur in reverse direction.
v Starts from autotrophs (the producer level, i.e., first trophic level) to Heterotrophs including plant eaters or Herbivores (second trophic level) and so on.
v The amount of energy decreases with successive trophic levels.
v Only About 1% of energy from the sun is used by green plants & rest remains unutilized.
v Similarly, there is loss of energy in each trophic level.
v The transfer of food energy between the organisms in an ecosystem can be tracked by constructing food chains, food webs, pyramids of numbers, biomass and energy and energy flow diagrams.
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