A pyramid of numbers for one big tree with many insects and birds is inverted, yet its energy pyramid is upright. Why?
A pyramid of numbers counts individuals, so one large tree supporting thousands of insects gives an inverted shape.
A pyramid of numbers counts individuals, so one large tree supporting thousands of insects gives an inverted shape. But an energy pyramid measures the energy stored at each level. The single tree fixes far more total energy than all the insects that feed on it, and the birds get even less. Because energy always decreases up the levels (the 10% law), the energy pyramid stays upright even when the number pyramid is inverted.
Key point
Energy always falls up the trophic levels, so the energy pyramid stays upright even when the number pyramid is inverted.
Common mistake
assuming an inverted number pyramid forces an inverted energy pyramid.
Memory tip
count-based pyramids can flip; energy pyramids never do.
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