BRAINCAKEPyramid of Biomass
A pyramid of biomass shows the total mass of living organisms at each trophic level, per unit area (or volume, for aquatic habitats), at one moment in time. It is usually given as dry mass in g m−2.
biomass = mean mass of one organism × number of organisms
Dry mass is used because the water content of organisms varies a lot and changes with conditions. To find it, samples are dried in an oven at about 80 °C (low enough that organic matter does not burn) and weighed repeatedly until the mass is constant. The organisms must be killed, so only small samples are taken and the results scaled up.
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Key terms in this lesson
- standing crop
- The biomass of a population present in an area at one moment in time.
More in The Efficiency of Ecosystems
- Food Chains
- Food Webs
- Ecological Pyramids
- Pyramid of Numbers
- Inverted Pyramids of Numbers
- Energy Losses in Producers
- Energy Losses between Consumers
- Efficiency of Energy Transfer
All 20 lessons in The Efficiency of Ecosystems · All Edexcel A-level Biology topics