Ecological Pyramid

The trophic level of an ecosystem can be expressed as diagrammatically as an ecological pyramid.

This ecological pyramid consists of three parts,

  1. Base
  2. Body 
  3. Apex
  • Producers form the base.
  • The body consists of successive trophic levels.
  • Carnivores form the apex.
An ecological pyramid



These ecological pyramids are represented in three different forms based on the number of organisms, biomass, and energy content of each trophic level.
  1. Pyramid of numbers.
  2. Pyramid of biomass.
  3. Pyramid of energy.

Pyramid of numbers


The diagrammatic representation of the total number of organisms in various trophic levels of an ecosystem. The number of producers are higher than that of herbivores, and the carnivores have the lowest numbers.

Pyramid of numbers



The pyramid of numbers is not always upright.
A single plant may support many consumers, then herbivore numbers are higher than producers.
In the parasitic food chains, the pyramid of numbers is always inverted.

Ex - In grassland, the grass is the main producer and the herbivores, and different levels of carnivores are found at successive feeding levels.

Inverted pyramid

Ex - In parasitic food chains. A single plant may support many parasites and each parasite, in turn, may provide nourishment for several hyper parasites.

Pyramid of biomass


The diagrammatic representation of the total biomass of organisms in various trophic levels of an ecosystem.
each level use dry weight as g/area 
This normally results in upright pyramids.

Pyramid of biomass of an aquatic ecosystem



Producers in these ecosystems have a short life cycle and rapid multiplication. As a result, they accumulate only a little organic matter, and they are heavily fed upon by herbivores zooplankton. 

The pyramid of biomass and numbers are calculated with regard to organisms present at a given time.

Pyramid of energy


The total energy content of each trophic level in an area of one square meter over a set period of time.
 
The total energy content of any trophic level depends on these factors,
  • Quantity of energy individuals takes in.
  • Quantity of energy used for metabolic process.
  • Quantity of energy that leaves as the trophic level as waste products after their metabolic process.
  • Quantity of energy that is stored in the particular trophic level.
The energy pyramid is always upright because, at each trophic level, a certain amount of energy is lost when transferring the energy from one level to another.