A rule of thumb in ecology is that approximately 10% of the biomass from one trophic level is converted to biomass in the next higher trophic level. For example, a hundred tons of grasses, forbs and shrubs may support ten tons of rabbits (and one ton of foxes).
Briefing paper on Trophic Structure of the Economy, CASSE
Good things, rules of thumb. 100 : 10 : 1.
Trophic refers to flows of food and energy. At the base of the trophic pyramid are the PRODUCERS: plants, their own regeneration limited by raw resources — water and sunlight.
Above plants, the CONSUMERS: primary consumers like rabbits, who eat the plants; secondary consumers like foxes, who eat the rabbits; higher level consumers like black bears; and multilevel service providers such as scavengers, decomposers and pollinators.
The size of the economy of nature – all trophic levels and service sectors in the aggregate – is dependent upon the amount of plant production.
Or as the Bible cannily puts it: “All flesh is grass” (Isaiah 40:6).