Pyramids of Biomass and Number
Pyramids of Biomass and Number: An Overview
- A food chain represents the flow of energy and nutrients through an ecosystem from producers to consumers.
- A pyramid of numbers shows the relative number of organisms at each level of the food chain.
- A pyramid of biomass represents the total mass of organisms at each level.
Characteristics of Pyramids of Numbers
- Pyramids of numbers do not always have a traditional ‘pyramid’ shape, they can be irregular.
- This can be due to the large number of small prey feeding a few large predators, or one large tree supporting many small birds.
- However, it gives a good visual illustration of the number of organisms in each trophic level.
Understanding Pyramids of Biomass
- Pyramids of biomass always have a traditional ‘pyramid’ shape because they represent the amount of biological material.
- Each layer represents the dry mass of all the organisms at that trophic level.
- Most of the energy stored in one trophic level is lost instead of being transferred to the next level. As such, biomass decreases as we move up the pyramid.
Energy in Pyramids of Biomass and Number
- Energy is lost between each trophic level due to different factors such as heat loss during metabolic processes, not all of a prey’s body being consumed or digested, and energy being expended in movement or reproduction.
- In general, only about 10% of energy is transferred from one trophic level to the next, which is reflected in the shape and structure of pyramids of biomass.
The Importance of Pyramids of Biomass and Number
- Pyramids of biomass and number provide a visual representation of the structure of an ecosystem.
- They can help illustrate concepts like energy transfer, trophic levels, and the balance of populations within an ecosystem.
- Consequently, they are valuable tools for ecological research and understanding the impact of changes in population size on an ecosystem.