Allows us to compare mass of organisms present in each trophic level at particular time.
How is Pyramid of Biomass Constructed?
Constructed based on standing mass — and dry mass of organisms → in each trophic level → at any one time
- Dry mass of organism → is mass of organism when all its water has been removed
Consider food chain:
graph LR grass --> rabbit rabbit --> snake snake --> eagle
→ biomass of lower trophic level → larger than biomass of next trophic level
What are Some Reasons for and Limitations of Using a Pyramid of Biomass to Represent Food Chain?
| Reasons | Limitations |
|---|---|
| Considers size and mass of organisms. → thus it is more accurate representation of energy flow through food chain than a pyramid of numbers | Organisms have to be killed to obtain biomass |
| Has to be constructed at a particular point in time |
Sample
Explain how organisms in first trophic level of xxx food chain produce biomass using energy from sun
- Biomass is produced via photosynthesis
- Where chlorophyll absorbs light energy and is converted into chemical energy in glucose molecules
- Glucose molecules can then be converted into other organic compounds such as starch and cellulose (which forms the biomass of the organism)
Sample
Explain why 4th trophic level has least biomass in this food chain 1 energy is passed from one trophic level to the next via feeding ; 2 the amount of energy available at each successive trophic level decreases as only 10% of energy gets transferred to the next trophic level ; 3 the rest of the energy is lost to the environment as heat through respiration/ uneaten parts / dead bodies / faeces / excretory products ; 4 the energy lost to the environment cannot return into the same system / cannot be recycled in the system 5 since the last trophic level receives the least energy, there is the least amount of energy available to carry out metabolic process like growth to increase biomass ;