Ecological
Pyramids: In a food chain,
producers and consumers at different trophic level are connected in terms of
number, biomass and energy. These properties reduces from producers to
consumers and representing these parameters for food chain gives a pyramid with
a broad base and a tapering apex (Figure 39.6). Ecological pyramids can be of
three types:
(a) Pyramid of Numbers
(b) pyramid of biomass
(c) pyramid of energy
Example of inverted ecological pyramid is provided by
parasitic food chains (Figure 39.7). A single mango tree supports large number
of birds, which in turn supports a large number of parasites like lice and
bugs. Hyperparasites, such as bacteria and fungus are the greatest in the
number and occupy the top of the inverted pyramids.
Flow of
energy in food chain: Sun
is the ultimate source of energy on earth and plants utilizes it to produce
food for rest of the member of the ecosystem. Only the 1% of the total energy
fall on green part of leaves is changed into the potential energy of the
organic substances, the rest of the energy dissipates as heat. To explain the
flow of energy, lindermann proposed the law of ten per cent law. This law
proposed that during transfer of food energy from one trophic level to the
other, only 10% is stored at higher trophic and the rest 90% is lost in
respiration, decomposition and waste in the form of heat (Figure 39.8). For
example, 5000 jules fall on leaves, it will convert only 50 jules into the
chemical form (food). It will be eaten by rabbit, he will get only 5 jules (10%
of 50 jules) on next trophic level. Rabbit will be consumed by carnivorous, and
they can be able store only 0.5 jules (10% of 5 jules).
Ecological Equilibrium: Ecosystem always remains in the state of equilibrium. The equilibrium is dynamic is nature and biotic components appear and disappear time to time due to their death or predator. In addition, decomposer converts the complex organic matter of dead plant and animals into the simple inorganic substances. These simple inorganic substances pass through the soil, plants and animals in a cyclic manner, and this keeps the life going on in an ecosystem. Thus, both biotic and abiotic components are in a dynamic state.
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