VPE 511: Environment and Environmental Hygiene (2+1)

IMPORTANCE OF FOOD CHAIN

• In the process of food chains, energy flow, nutrient cycling, ecological balance and biological magnification of some chemicals take place. Pesticides and heavy metals are nonbiodegradable. They are carried along the food chain.

(C₁) Food Web

• It is a network of Food chains where different types of organisms are connected different levels. There are a number of options of eating and being eaten.
• Food web opens flow of food energy.
• Food web gives greater stability to the ecosystem.
• In a linear food chain if one species becomes extinct then the species in the subsequent trophic levels are affected.
• In a food web number of options are available at each trophic level e.g. a field mouse may be eaten by a wild cat, a snake or an owl.

FOOD WEB

(C₂) Ecological Pyramids

• They were first devised by Charles Elton (1927) So they, are also called Eltonion Pyramids.
• Graphic representation of trophic structure and function of an ecosystem starting with producers at the base and successive trophic levels forming the apex are called Ecological Pyramids.
• There are three Parameters of each Trophic level:
• Number of individuals
• Amount of Biomass
• Amount of Energy
• Three types of Pyramids are as follows:
• Pyramid of numbers
• Pyramid of Biomass
• Pyramid of Energy