PRACTICES Ecological Pyramids
Ecologists use ecological pyramids to understand how energy flows through an ecosystem
The different types of pyramids ecologists construct may include information on energy.
the amount of biomass, or a pyramid of numbers (iepopulation size). Ecologists find the
pyramid a good structure because it shows who are the primary producers (located on the
bottom) as we go up the pyramid, the primary, secondary, and third-level consumers.
It is now your turn to be an ecologist and illustrate how energy flows through either a
stream or forest. Choose one of the two following ecosystems to construct a pyramid of
biomass and a pyramid of numbers:
Ecosystem: Stream
Population
(number of
individuals)
29,000
Organism
Macroinvertebrates
Fish
Macrophytes
Osprey
Biomass
(g/m?)
180
98
240
Trophic Level
Primary Consumers
Secondary Consumers
Primary Producers
Tertiary Consumers
308
54,000
4
2.5
Ecosystem: Forest
Population
(number of
individuals)
Biomass (g/m²)
0.90
Organism
Lynx
Grass and Shrubs
Songbirds
Owls
Trophic Level
Tertiary Consumers
Primary Producers
Secondary Consumers
Primary Consumers
1500
20,000
800
640
280
9
Graphing
1. Construct a pyramid of biomass for your ecosystem. Label each trophic level, the
organism in the trophic level, and the amount of biomass produced.
2. Construct a pyramid of numbers for your ecosystem. Label each trophic level, the
organism in the trophic level, and the number of organisms.