Ecological pyramids are graphical representations of relationship between the different trophic levels of food chains on the basis of energy, number and biomass productivity. It can be observed that these pyramids are in the shape of actual pyramids with the base being the broadest, which is covered by the lowest trophic level i.e., producers. The next level is occupied by the next trophic level, i.e., the primary consumer and so on as that of a food chain. All the calculations for construction of these types of ecological pyramids must take into account all the organisms in a particular trophic level because a sample space of a few number or a few species will end up giving huge level of errors.
There basically exists three types of ecological pyramids. They are as follows:
- Pyramid of numbers – In this pyramid, the number of organisms in each trophic level is considered as a level in the pyramid. The pyramid of numbers is usually upright except for the some situations like that of the detritus food chain, where many organisms feed on one dead plant or animal.
- Pyramid of biomass – In this pyramid, each level takes into account the amount of biomass produced by each trophic level. The pyramid of biomass is also upright except of that observed in oceans where large numbers of zooplanktons depend on relatively smaller number of phytoplanktons.
- Pyramid of energy – Pyramid of energy is the only pyramid which is always upright as the energy flow in a food chain is always unidirectional. Also, with every increasing trophic level, some energy is lost into the environment.
Even though we have discussed about the easy way of representation of numbers, biomass and energy flow, these pyramids have a lot of limitations. They are as follows:
- More than one species may occupy multiple trophic levels as in case of food web. Thus, this system does not take into account food webs.
- The saprophytes are not considered in any of the pyramids even though they form an important part of various ecosystems.
We have thus discussed about pyramid of numbers, pyramid of biomass and pyramid of energy. To learn more, join Byju’s classes.