Systems analysis in the Marion Lake IBP Project

Modelling work in the Marion Lake Project has led to a number of simulation models that trace the fate of primary production through consumer components of the lake ecosystem. Two of these models illustrate extremes in realism and generality: a simple compartment-flow system, and a detailed population model that represents density and individual growth of 24 major animal species. Both models are adequate to describe normal seasonal changes in the variables that they represent, but the simple model may give better predictions about response of the system to disturbance. Modelling efforts would have been much more successful if they had been initiated at the start of the project rather than after much field data had already been collected.