Introduction.
Ecological pyramids are used to indicate trophic structures of an ecosystem. A diagram shaped likea pyramid is developed to represent the numbers of organisms, their biomass, and energy relationships. In a food chain, a fraction of energy is usually lost in the form of heat. Therefore, organisms usually pass lesser energy from one trophic level to the next. A pyramid is formed because of this loss of energy through a food chain. The high step in an ecological pyramid containsa lower number of individuals than the lower steps. There are three types of pyramids which may be found among organisms in the ecosystem.
- Pyramid of numbers
- Pyramid of biomass
- Pyramid of energy
Pyramid of numbers.
This indicates the number of individual organisms at different trophic levels of a food chain. Charles Elton advanced this type of pyramid in 1927 by pointing out the huge difference in the number of organisms involved in each step of the food chain. The numbers of organisms decrease rapidly above each successive link of the pyramid. In the pyramid, there must be enough plants to produce food at the bottom, and the number continues decreasing from one consumer to the other hence the shape of the pyramid. The number of a consumer cannot be similar to that of its prey; otherwise, they would risk being wiped out. A pyramid of numbers helps identify the number of organisms at each trophic level. It can also help to find out how one organism’s population can affect another.
Pyramid of Biomass.
The pyramid of biomass is formed by the biomass of the members of the food chain. This pyramid indicates a decrease in the biomass in each tropical level from the base to the apex of the pyramid. There are two types of the pyramid of biomass that is an inverted and upright pyramid of biomass. An inverted pyramid is where the mass of producers is higher than that of consumers. A pyramid of biomass helps in quantifying the biomass at each trophic level.
Pyramid of Energy.
This pyramid indicates the amount of energy flow at each level and the role that various organisms play in the transfer of energy. It also indicates the amount of energy needed to support the next trophic level flowing up. As you move from the bottom to the top through trophic levels, energy decreases. The pyramid of energy is useful in showing the transfer of energy from one organism to another.