From Lindeman’s law it is clear that only 10% of energy is utilized at each trophic level and rest 90% goes off. This flow of energy can briefly be expressed as below –
(i) About 1000J radiant energy comes to the earth from the sun. Out of this, only 10% of the total energy is used up by green plants in the process of Photosynthesis. Remaining 990J of energy escapes away into the atmosphere. 10J of energy is stored in the form of chemical energy in starch and sugars.
(ii) The energy stored by plants reaches into the body of the Primary Consumer. Some of the energy that goes into the bodies of consumers is utilized in their metabolic processes.
(iii) The remaining energy of the bodies of primary consumers reaches into the bodies of the Secondary Consumers. There too some energy is used in the metabolic processes of their bodies. Thus every consumer uses some of the energy it gets from the earlier consumer.
In this way, every living being consumes some energy. Some energy is lost into atmosphere from the bodies of living beings. This energy is called as community heat.
(iv)When dead bodies of consumers are decomposed or burnt the energy contained in their bodies is liberated into atmosphere. Thus only 10% of the total energy is utilized and 90% energy is wasted away. The earth is an open system for energy but for substances it is a closed system.
What is Bio-geo-chemical cycle?
Different types of grains, fruits, seeds and vegetables contain nutrients that are essential for our lives. These are chemical substances that are synthesized in living cells. These chemicals are called as Bio-chemicals.
These bio-chemicals are made up of carbon, hydrogen, nitrogen, oxygen, phosphorus, sulphur, iron, calcium, sodium etc. that are fundamentally found on rocks and soils. These elements are called as Geo-chemicals.
Roots of plants absorb these geo-chemicals in the medium of water. Combining these elements green plants synthesize bio-chemicals. The bio-chemicals move across the biosphere through food-chains.
When organisms die, different decomposers decompose their bodies into simpler substances. Thus bio-chemicals go into the earth and get mixed with the soil. Plant roots absorb them again in the medium of water.
The cyclic movement of chemical substances like carbon, nitrogen, phosphorus, sulphur etc. in the biosphere through soil, water and living organisms is called as Bio-geo-chemical cycles.
When pesticide chemicals are applied on crops these poisons get absorbed in plants and grains. These move through food-chains and get deposited in the fatty tissues of consumers and their potency is increased gradually. This is called as Bio magnification.