Question

What are the three types of ecological pyramids? What information is conveyed by each pyramid with regard to structure, function and energy in the ecosystem.

Answer 1

Ecological pyramids:

Ecological pyramids are the visual representation of a particular ecological parameter like number, biomass or energy across the trophic levels in the food chain in a sequential manner. The base represents the producers, the subsequent levels represent the herbivores followed by carnivores.

It is mainly of three kinds:

● Pyramid of numbers

● Pyramid of biomass

● Pyramid of energy

Pyramid of number:

● Pyramid of numbers conveys the number of individuals per unit area of various trophic levels.

● It can be upright or inverted.

○ Upright pyramid:- The number of individuals at the higher trophic level decreases for example in the case of grassland and pond ecosystems.

○ In some cases the pyramid of numbers is inverted where the number of individuals are more at higher level, for example a big tree supporting a large number of birds which in turn supports a large number of ectoparasites.

Pyramid of biomass:

● Pyramid of biomass gives us information about the amount of biomass (amount of living organic matter) present per unit area.

● Biomass depends upon the reproductive potential and longevity.

● Maximum biomass occurs in producers.

● Pyramid of biomass is upright for terrestrial ecosystems but inverted in aquatic ecosystems.

Pyramid of energy:

Pyramid of energy represents the amount of energy trapped per unit time and area.

It is always upright as energy passes from one trophic level to the other. Only $10\%$ of the energy is transferred as some of the energy is lost as heat.