Food Web

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ecosystem. In a forest, if deer become rare or get wiped out by a disease of any natural calamity, the predator. such as lion. can feed on other animals such as fox, *olf, crane etc.
till the usual prey animals are available again (see Fig. 14.3). In brief, we can say that many interlocking food chains make it possible for the living beings to survive minor or major 'setbacks and changes in their

surroundings. Thus, inteiloctiig food chains provide st;bility td the ecosystem.

Fig' 14'3: A food web showing the main food links. Note that the starting point for each chain is a plant, and
several food chains are interconnected to form a food web.

14.3.4 Energy Flow in the Ecosystem
The principal source ofenergy for any ecosystem is sunlight. In the earlier sub-section (14.3.1) you have studied that solar energy is converted by plants into food materials, and is
stored within the body of the plant. All food materials that we or other animals consume are
manufactured directly or indirectly by plants. Think of your breakfast, bread is made of a
cereal that is produced from plant material. egg from hen which has fed on plant products; and milk from cow which has consumed grass or fodder derived from ptants. In a nutsheli, the energy that we obtain from plants either by burning wood or by eating them, represents the solar energy trapped by the plants. We are dependent on the stored resources of solar

energy. When we eat meat, we obtain energy that had been stored by plants several years before and then taken up by an animal like a goat through grazing.\ffi"n *" cut firewood
for fuel, we obtain energy accurnulated and stored by trees for perhaps a century or more.
when we burn coal or petroleum, we obtain solar energy rto."d by piant life, millions of
years ago.
Now let us trace the energy flow through an ecosystem. This is represented diagramatically

inFig.l4.4.

Fig. 14.4: Energy flow in an ecosystem.

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