A Critical Reexamination of Food Web Patterns in Real Ecosystems

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The central aim of this research is to provide a critical reappraisal of so-called empirical "laws" for trophic structure in ecosystems. The first whole-system data base designed specifically to represent the trophic structure of a large-scale ecosystem will be assembled. Efforts will be focused on Little Rock Lake, Wisconsin. This represents a long-term study site where much of the desired information has already been gathered and where a research team has agreed to collaborate to resolve the trophic structure of the system. The protocol for this study will involve an extended visit to the field station associated with the lake in order to coordinate the resolution of feeding relations within and between the major subsystems involved. The initial focus will be on the aquatic environment because it represents the largest fraction of the systems upon which the food web laws are based, and because the chance of constructing reasonable complete food webs is likely to be highest here. These data will represent at lease an order of magnitude improvement over what is currently available in the food web literature. Among the details that will be included in this study are: a full and more even-handed resolution of species involved and their feeding intensities; temporal variability in food web structure with season and ontogeny; the magnitudes of energy and material flows in aggregated webs; interaction strength; the effects on food web patterns of studying incomplete subsystems; and the variation in food web structure with the systematic incorporation of major to minor interactions. Among the specific questions that will be asked is how representative of real systems are the data upon which many food web generalizations are based? Here, credible data from the documented systems will be used to statistically test whether a large collection of questionable data are to be believed.