FOOD WEB SCIENCE: MOVING ON THE PATH FROM ABSTRACTION TO PREDICTION

This chapter explores some basic issues in food web research, evaluates major obstacles impeding empirical research, and proposes a research approach aimed at improving predictive models through descriptive and experimental studies of modules within large, complex food webs. At least four basic models of food web structure can be proposed. One model could be called the “Christmas tree” model in which production dynamics and ecosystem processes are determined by a relatively small number of structural species. A second alternative is the “onion” model in which the core and peripheral species influence each other's dynamics, with the core species having a greater influence. A third food web structure is the “spider web” model in which every species affects every other species via the network of direct and indirect pathways. The fourth model of food web structure is called the “internet” model. Like any scientific endeavor, research on food webs advances on four interacting fronts: description, theory, model testing, and evaluation. Evaluation invariably leads to theory revision, and the loop begins again. After several trips around this loop, a model may begin to successfully predict observations, and we gain confidence for applications to solve practical problems. Empirical food web studies must carefully consider the dynamical consequences of definitions for operational units and scale, resolution, and sample variability. In many respects, food web research is basic yet complicated and esoteric yet essential for natural resource management.