Phosphorus limits tropical rain forest litter fauna

The stoichiometry of resources may explain bottom-up regulation of higher trophic levels. We tested the effects of soil and litter nutrient stoichiometry on the invertebrate litter fauna of a Costa Rican tropical rain forest. Animal densities were estimated from 15 sites across a phosphorus gradient. The density of the invertebrate litter fauna varied considerably, and was strongly tied to soil and litter phosphorus concentrations. An increase in phosphorus concentrations corresponded with an equally proportionate increase in animal densities. Natural variation in nutrient levels can thus serve as a predictor of density in a highly diverse tropical animal community.