Ecological Pyramids: Understanding the Structure of Ecosystems, Summaries of Zoology

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Ecological Pyramids

B.Sc. Part-I, Paper-I, Group-B Dr. Vandana Kumari, Department of Zoology, R.C.S. College, Manjhaul

Introduction

 The structure of ecosystems can be visualized with ecological pyramids, which were first described by the pioneering studies of Charles Elton in the 1920s. Ecological pyramids show the relative amounts of various parameters (such as number of organisms, energy, and biomass) across trophic levels. It has numerous names like Eltonian pyramid after Charles Elton, energy pyramid, trophic pyramid, and food pyramid.  Ecological Pyramid is a graphical depiction which is meant to illustrate the relationship between different living organisms at different level in an ecosystem. In an ecosystem there are three types of ecological pyramid.  The pyramid consists of a no. of horizontal bars showing specific trophic levels which are arranged sequentially from primary producer level through herbivores, carnivores onwards. The length of each bar represent the total no. of individuals at each trophic level in an ecosystem.  The number, biomass and energy of organism gradually decreases with each step from the producer level to consumer level and the diagrammatic representation takes a pyramid shape.

Pyramid of Numbers

 Pyramid of numbers represent the total numbers of individuals(population) present in each trophic level. This deals with the relationship between the numbers of primary producers and consumers of different levels. This pyramid is quite convenient especially when it comes to counting the number of organisms. Counting is a simple task and it can be done over the years to determine the changes in a specific ecosystem. It is a graphic representation of the total no. of individuals of different species belonging to each trophic level in an ecosystem.  Pyramid of number is divided into two different form depending on the number of organism ❑ Upright Pyramid of number ❑ Inverted Pyramid of number

Inverted pyramid of number

 An inverted pyramid is actually the opposite of the upright pyramid. It can closely be observed in tree ecosystem, where trees are the producers and insects are the consumers.

Drawbacks of pyramid of numbers

 Amongst the three ecosystem pyramids. The pyramid of number is the most incorrect, as it does not take into consideration the exact population. Hence, it cannot completely elaborate on the trophic structure in a system.  This pyramid ignores the biomass of species and it doesn’t show the energy transferred between individual groups.  Pyramids of numbers are not very functional as they do not give a clear or true picture of the food chain.

Upright pyramid of biomass

An example of an upright pyramid is the terrestrial ecosystem. It has a large base mainly consists of primary consumers, the smaller trophic levels are located at the top.

Inverted pyramid of biomass

Pyramid of energy

Significance of ecological pyramid

➢ They show the feeding of different organisms in different ecosystems. ➢ It shows the efficiency of energy transfer. ➢ The condition of the ecosystem can be monitored, and any further damage can be prevented.