Dynamic structure of a food web model: comparison with a food chain model

In this paper the dynamic behaviour of a food web model with a high diversity in time scales and function is contrasted with the dynamic behaviour of a food chain model. The models describe the trophic dynamics in pelagic systems. Body weight is chosen as the central variable determining an organism's dynamic and ecological properties. In the web model consumers are further distinguished by the selectivity of their feeding behaviour. Because of its dynamic and flexible network, the web model buffers the effects of structural changes such as adding a top predator and changes in the environment such as altering nutrient input. This behaviour is in sharp contrast to the sensitivity of the chain model. The transfer of energy up the trophic gradient proves to be far more efficient in the web than in the chain model. This article provides an example of a systematic approach to investigating the influence of structural and dynamic complexity of ecological networks for ecosystem dynamics and function. Such approaches are essential for improving our understanding of ecosystem regulation and for bridging different levels of ecological organization. (C) 1997 Elsevier Science B.V.