The graphical representation of the relationship between various living beings at various trophic levels within a food chain is called an ecological pyramid. The pyramid is formed on the basis of the number of organisms, energy and biomass, and just like the name suggests, these are shaped in the form of a pyramid.
The theory of ecological pyramid was suggested by Raymond Linderman and G.Evylen Hutchinson. The ecological pyramid is also often known as the energy pyramid.
The bottom of the pyramid, which is also the broadest part is occupied by the ones at the first trophic level, that is the producers. The next level of the pyramid is occupied by primary consumers. This is followed by the next level in the pyramid, belonging to the secondary and tertiary consumers.
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The ecological pyramid is also used to explain how various organisms in an ecosystem are related to one another. The pyramid ideally shows who is consumed by whom, while also showing the order in which the energy flows.
The flow of energy in an ecological pyramid is from bottom to top, which means energy from the autotrophs, who are also the primary producers, goes to the primary consumers, meaning those who consume these plants. At the next step, the energy goes to the secondary consumers who eat the primary consumers. This hierarchical system completes the above diagram.
Types of Ecological Pyramid
Ecological pyramids can be of three kinds. These are as follows:
Pyramid of numbers
Pyramid of biomass
Pyramid of energy
This ecological pyramid takes into account the number of organisms present at each trophic level, making up that level for the pyramid. The number of organisms decreases while going higher up the pyramid. The ones at the bottom are the producers who are present in the largest number and hence form the base of the ecological pyramid.
This ecological pyramid takes into consideration the amount of biomass that is produced at each trophic level as it adds to the pyramid. This pyramid is usually upright except for exceptional cases like the marine ecosystem where the number of phytoplanktons is lesser than the number of zooplanktons that depend on them.
The producers or the autotrophs have the highest level of biomass in this pyramid. The next level of primary consumers have lesser biomass than the producers and similarly, the secondary consumers have lesser biomass than the primary consumers. As a result, the level of the pyramid that has the least biomass is at the top of the pyramid.
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This pyramid shows the flow of energy that is in the direction of the consumers and comes from the producers. This pyramid is always in an upright form since it signifies the flow of energy within a food chain, something that is always unidirectional.
The energy pyramid represents the energy flowing through each trophic level, while also showing the amount of energy at each level and the energy that is lost during the transfer to another trophic level. In simpler terms, this pyramid helps to quantify the energy transfer within the food chain as it goes from one organism to another.
The energy pyramid is always upright because the energy level only decreases as it moves in the upward direction, from one level to the next one.
The ecological pyramid is highly significant in an ecosystem and the reasons are explained below-
An ecological pyramid shows how efficiently energy is transferred from one level to the other and also helps to quantify energy in a food chain.
This pyramid also shows how various organisms in various ecosystems feed on each other, highlights their food patterns and explains the relationship between the various levels within it.
The ecological pyramid also helps in monitoring the overall health and condition of an ecosystem, and helps in restoring balance. It also helps to understand how any further damage to an ecosystem can be prevented.
The ecological pyramid comes with its own set of limitations since it overlooks a couple of important aspects. These have been discussed below:
The ecological pyramid does not take saprophytes into consideration and assumes them as unimportant in the ecosystem, even though they play a highly important role in maintaining the balance of the environment.
There is no mention of diurnal or seasonal variations in this pyramid, the concept of climate or seasons is completely unassumed here.
The ecological pyramid is only applicable in case of simple food chains, something that in itself is a rarity.
Neither does the ecological pyramid explain the concept of a food web.
This pyramid does not mention anything about the rate of energy transfer that occurs from one trophic level to the other trophic level.
Important sources of energy like litter and humus are completely ignored in the ecological pyramid even though their importance in the ecosystem is unparalleled.
The same species existing at different levels in a pyramid is not taken into consideration.