In a forest ecosystem, the pyramid of number is typically spindle-shaped rather than upright because a single large producer (one tree) supports many herbivores (birds).

This contrasts with grasslands or ponds, where thousands of small producers (grass or algae) support a smaller number of primary consumers.

While the biomass in a forest remains upright, the sheer count of individuals at the base is lower than at the herbivore level.

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