■ PYRAMID OF ENERGY
◇ Energy pyramid is most suitable to compare the functional roles of the trophic levels in an ecosystem.
◇ An energy pyramid represents the amount of energy at each trophic level and loss of energy at each transfer to another trophic level.
◇ Hence the pyramid is always upward, with a large energy base at the bottom.
◇ Suppose an ecosystem receives 1000 calories of light energy on a particular day, most of the energy is not absorbed. Some of it is reflected to space.
◇ Of the energy absorbed only a small portion is utilized by green plants, out of which the plant uses up some for respi ration; therefore only 100 calories are stored as energy-rich materials.
◇ Now suppose an animal, say a deer, eats the plant containing 100 calories of food energy. The deer use some of it for its metabolism and stores only 10 calories as food energy.
◇ A lion that eats the deer gets an even smaller amount of energy.