Theoretical considerations on the combined use of System Dynamics and individual-based modeling in ecology

Modeling could be summed up as the task of reproducing the structure and imitating the behavior of complex real-life systems with components interacting with one another at different scales. In many disciplines of ecology, System Dynamics and more recently Individual-Based modeling have emerged as the major tools to support this task. These techniques have usually been considered until now as exclusive alternatives instead of synergistic tools. The present paper starts by presenting the two approaches, and compares them to identify their strong and weak points depending on the type of components constituting the system under consideration. Then we isolate a class of systems difficult or in some cases impossible to model dynamically using any of these approaches alone, because of conceptual limitations. We further point out the usefulness of merging the two paradigms inside of a hybrid modeling framework to handle this class of systems, and present what we consider as the elementary combination patterns of System Dynamics and Individual-Based modeling. Since the power of this promising approach has been unexplored in most fields of ecology, we suggest some possible applications illustrating its usefulness.