"Models of a same system may differ greatly in scale and level of detail. The implications of this are examined, in general and more specifically in relation to forest growth models. The nature of modelling is discussed, distinguishing descriptive and predictive models, and briefly describing the concepts of dynamical systems and state space. Through examples, I demonstrate limits to predictability that can make reliable predictions impossible at the individual level. A complete understanding of the functioning of a system, or its computer si8mulation, do not imply being able to predict its behaviour. Although detailed models are useful for research purposed, low-dimensional aggregated models are generally more appropriate for decision-making."
