CONSUMERS AS MAXIMIZERS OF MATTER AND ENERGY-FLOW IN ECOSYSTEMS

This article investigates the conditions under which consumers maximiz e matter and energy flow in ecosystems, using a simple, general, abstr act nutrient-limited ecosystem model. The model is analyzed for severa l functional forms of trophic interactions. The conditions for enhance ment of energy dow by consumers are found to be qualitatively the same in all cases. The first and most important condition is that consumer s act to accelerate the circulation of matter within the ecosystem; mo re precisely, the mean transit time of nutrients in the path consumers -decomposers-nutrient pool must be sufficiently smaller than their mea n transit time in the path producers-decomposers-nutrient pool. The se cond condition is that the total quantity of nutrients in the ecosyste m must be higher than some threshold value. The third condition is tha t consumption rate must be moderate. These conditions being usually me t, it is likely that consumers as a whole do generally play a role of maximizers of matter and energy flow in stable natural ecosystems.