Ecological Pyramids By K Sharath Deepika Ecological Pyramids

Ecological Pyramids By, K. Sharath Deepika

�Ecological Pyramids: ü In any ECOSYSTEM, a relationship exists between the individuals of biotic component with reference to the food chain. ü This relationship between individuals like Producers Herbivores Carnivores, can be shown digrammatically by means of Ecological pyramids. ü These pyramids where first given by a British Ecologist Charles Elton in 1927, hence they are called “ELTONIAN

A simple ecological pyramid showing the different trophic levels.

ü An ecological pyramid is a graphical representation of an parameter like number of individuals or amount of biomass, energy present in the various trophic levels of a food chain with producer forming the base. ü The shape of the pyramid may be upright, inverted, spindle shaped etc. ü The ecological pyramids can be divided into three types 1. Pyramid of Numbers 2. Pyramid of Biomass 3. Pyramid of Energy.

1. Pyramid of Numbers: § The pyramid of numbers shows the relationship between producers, carnivores and the omnivores in terms of their numbers. § Mostly the pyramid of numbers is straight or upright with the number of individuals in the successive trophic level decreases from base to the apex. § Maximum number is assumed at producer level and minimum at the omnivore level, hence appears upright.

2. Pyramid of Biomass: § The amount of living or organic matter present in the environment is called Biomass. § This pyramid shows the relationship between the living matter at different trophic levels. § The pyramid of biomass is upright in terrestrial ecosystem and inverted in aquatic ecosystem.

3. Pyramid of Energy: § The pyramid of energy shows the flow of energy from one trophic level of a community to the next. § The shape of pyramid is always UPRIGHT [since the total energy at each level is calculated]. § The energy content is generally expressed as K. cal / m² / yr. § Maximum energy content is present in the producers and as the energy passes on in the food chain it decreases, because of its utilization in performing life activities.

�Energy Ø The Flow In Ecosystem: - functioning of the ecosystem depends upon the flow of energy through matter. Ø Energy enters the system through solar radiation and gets converted to chemical energy passes through each of the trophic level. Ø The one way flow of energy is observed in the ecosystem which is governed by two laws:

�First Law: ü Energy may be transformed from one state to another, but can neither be created nor destroyed. �Second Law: ü Every transformation of energy is accompanied by some dispersion or loss of energy in the form of heat.

�Energy § § Flow Is Unidirectional: In an Ecosystem, the producers prepare the food utilizing the solar energy. This energy is now in the form of food, moves through the trophic levels in a particular direction. The flow of energy is always unidirectional from producers to consumers. Energy cannot be transformed in reverse direction i. e consumers to producers.

�Gradual Decrease In The Amount Of Energy: The amount of energy transferred decreases with successive trophic levels. § Producers capture only a small fraction of solar energy part of which is utilized in the bodily functions and the remaining is transferred to the next trophic level. § Hence the energy from the producers to the consumers reduces gradually. §

The ratio between energy flow at different points along the chain expressed as percentage is called ECOLOGICAL EFFICIENCY. § Slobodkin (1959) suggested that the transfer of energy from one trophic level to the next is of the order of 10% and this is termed as. GROSS ECOLOGICAL EFFICIENCY § Thus if there are 100 calories of NP at producer level, only 10 calories of secondary production would be expected at the herbivore level, only 1 calorie at first carnivore level and so on. This can be called as TEN PERCENT RULE. §