Ecological Pyramid and Ecological Succession

By now, you have learned that there is a lot of interaction between all the components of an ecosystem. However, did you know that we can represent this relationship between the energy and biomass of organisms through a simple diagram? An Ecological pyramid shows precisely this relationship in a diagrammatic format. The predictable changes that are seen in organisms are shown by ecological succession.

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Ecological Pyramid

Ecological pyramid definition – It is a graphic representation of the relationship between organisms at various trophic levels in a food chain.

The basis of an ecological pyramid is biomass, energy, and number. Just as the name suggests, ecological pyramids are in the shape of a pyramid. The concept was first introduced by Charles Elton, the pioneer British Ecologist.

The bottom of an ecological pyramid is the broadest and is occupied by the producers. They form the first trophic level. Just as in a food chain, in the ecological pyramid also, primary consumers occupy the next level. This is because primary consumers consume producers. Similarly, secondary consumers occupy the third level. And then the tertiary consumers that occupy the next level and so on.

Download Ecosystem Cheat Sheet PDF

Ecosystem Cheatsheet

Types of Ecological Pyramids

Depending on the factors that we use to represent an ecological pyramid, there are three types. They are:

  • Ecological pyramid of numbers– Here, the important factor is the number of organisms in each trophic level.  As we go up the levels of the pyramid, the number of organisms decreases. The producers form the largest number and hence, are at the bottom of the pyramid.
  • Ecological pyramid of energy– The energy pyramid is an upright pyramid that represents the flow of energy from the producers to the final consumers.
  • Ecological pyramid of biomass – This pyramid represents the amount of biomass of the organisms present at each trophic level. Biomass is nothing but the weight of the organisms.

In general, all ecological pyramids are upright, except in certain cases. For example, in a detritus food chain, the pyramid of numbers is not upright. This is because many organisms feed on one dead plant or animal. The pyramid of biomass in an ocean is also inverted. This is because the biomass of producers in an ocean is less. But a point of note is that the energy pyramid is always upright as the flow of energy is unidirectional.

Ecological Pyramid

(Source – Encyclopedia Britannica)

Ecological Succession

A characteristic feature of biological communities is that their structure and composition changes. These changes are according to certain changes in environmental conditions. Some of these changes occur in a more predictable and orderly fashion. The phenomenon through which these changes occur in ecological communities is ecological succession. This is an important aspect of the study of ecology and forms the core of ecological science.

Now, any form of disturbance or formation of new habitats in the ecosystem can trigger the ecological succession.

When the changes create a community that is almost in equilibrium with the environment, then we call the community as a climax community. In a given ecological area, the communities change successively. This sequence of communities is a sere. The transitional communities are known as seral communities. As the seral communities progress, there is an increase in the diversity of organisms, numbers, and biomass.

The starting point of ecological succession can be traced back to millions and millions of years back when living organisms never existed. Slowly, new organisms started developing. The diversity of the planet started showing changes. These changes were occurring along with the change in the environment.

Types of Ecological Succession

Ecological succession is mainly of two types: Primary succession and secondary succession. The primary succession is a slow process that initiates in areas where there are no living organisms. Secondary succession begins in areas that were once inhabited but destroyed due to environmental disturbances. Secondary succession is generally faster, as most of the other factors are already present.

Learn more about Biogeochemical Cycles here.

Solved Questions for You

Q: Are there any species that live on rock and be the starting point of ecological succession?

Ans: Lichens are organisms that can live on a rock. They can form the pioneer species on a bare rock. This is due to the fact that they have the ability to dissolve rock and help in weathering and soil formation.

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