Models in Ecology

摘要

Models are usually surrounded by an atmospliere of mistery that limits their use. Our aire is to end this myth in order to promote the diffusion of models as tools to solve the problems faced by ecosystem managers. The retain points of this article are the concepts of a model as a simplification of a system, and system as a whole that contains at least two interrelated parts. The three basic problems of constructing and using models, which can be deduced from the analysis of those concepts, are the definition of the system, their parts, and the interactions among them. There is not ti single kind of model or method to construct it: the structure, the construction, and the achievements of each model closely depend on the problem to be solved with it. As an example, this paper details the different steps followed to construct a model, used with educational purposes, which predicts the biomass dynamics of the steppe of SW Chubut, Argentina, and its variability in response to environmental conditions. We discuss some discrepaticies between the results of the model and our knowledge of the system, and show how some of the basic assumptions must be reformulated