Q.18. What are ecological pyramids? Explain the different types of ecological pyramids giving suitable examples. (AKTU. - 2009 - 10)
Related Questions -
Q. Explain the term ecological pyramid. Depict various types of ecological pyramid with suitable examples. (AKTU. - 2011 - 12)
Q. What type of ecological pyramid is always upright? Explain. (AKTU. - 2012 -13)
Q. Differentiate between upright and inverted ecological pyramid with suitable example. (AKTU. - 2012 - 13)
Ans. There exist the relationship between the numbers, biomass and energy of producers, primary, secondary and tertiary consumers in any ecosystem. These relationships can be drawn graphically in the form of pyramids.
Definition : Graphic representation of trophic structure and function of an ecosystem, starting with producers at the base and successive trophic levels forming the apex is known as an ecological pyramid.
Ecological pyramids are of three types:
1. Pyramid of numbers : It represents the number of individual organisms at each trophic level. It shows the relationship between producers, herbivores and carnivores on the bais of their number. These can form upright or inverted type depending upon the type of ecosystem.
Example: Grassland ecosystem : Forms an upright pyramid of number. The producers in this type are grasses and are very large in number. So they form a broad base. The herbivores are insects carnivores are birds, hawks and these are less in number. Hence the pyramid apex become narrows forming an upright pyramid.
Example: Parasitic food chain : Forms an inverted pyramid of number. Producers like big trees are less in number and herbivores like birds, and parasites are greater in number, and the hyper parasites are in the greatest number, thus forming an inverted pyramid.
2. Pyramid of biomass : It is based upon the total biomass (dry matter) at each trophic level; in a food chain. The pyramid of biomass can also be upright or inverted. Forest ecosystem is an example of the upright pyramid of biomass, because the producers (trees) accumulate a huge biomass while the consumer’s total biomass declines at higher trophic levels, forming an upright pyramid of biomass.
Pond Ecosystem shows an inverted pyramid of biomass. The total biomass of producers is much less as compared to herbivores, carnivores and tertiary carnivores, Thus pyramid form inverted form.
3. Pyramid of energy : In this type of pyramid, the amount of energy at each trophic level is considered. It gives the best representation of trophic relationships and it is always upright, as there is always a gradual decrease (about 90%) in the energy contenl at successive trophic levels. Only 10% of energy passes to next trophic level.
