Introduction

The allometric approach is often unsatisfying, because it draws far more from physiology than ecology. Thus, bare scaling relationships (Table 12.1) suggest that all animals of the same size will behave in the same way, despite differences in their biotic and physical environments. Clearly, this is not the case; but empirical relations rarely exist that would permit descriptions of the habitat's modifications of allometric equations. Just as we cannot tell what effect a particular environment will have on a given organism, we also have no way of predicting what effects the organism will have on its ecosystem.

Simulation models address this problem, because the models permit the investigator a larger creative role than do empirical relations alone. If a necessary piece of information is unknown, the modeler can supply a “reasonable assumption” (a good guess) instead. Because such models treat whole, if hypothetical, ecosystems, they allow a further extension of body size relations to include the effect of size on community level processes, like succession and material flow. Most of this chapter discusses the implications of putting a single allometric organism or population into the biotic environment provided by a community of such organisms. This is a simple demonstration of the role of imagination in extending and connecting empirical relationships.