An individual layer on the pyramid of numbers which represents types of organisms living at parallel levels on food chains. All herbivores live at one level, all primary carnivores on the next level, all secondary carnivores on the next level, and so on. The animals on each level are remarkably distinct in size from those on other levels; there is a clear jump in size between an insect and a bird, for example.

The trophic biology of a taxon (species/family/class) fundamentally constrains its ability to convert productivity into individuals. Predator taxa require at least an order of magnitude more net primary productivity (NPP) to support an individual than the trophic level upon which it feeds; the more trophic links between NPP and a consumer taxocene (taxonomically related set of species within a community), the more energy is necessary to support viable populations of its individuals. If taxocene abundance is energy limited, consumer taxocenes that occupy broad NPP gradients should show a predominance of lower trophic levels at low NPP. Higher trophic levels should accrue as NPP increases, and taxocenes comprised largely of predators should be under-represented at lower NPP (Kaspari (2001) Glob. Ecol. & Biogeog. 10, 3).

Trophic level