Procedures and problems in modelling ecosystems: An agriculturalist's viewpoint.

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Any discussion of systems modelling is handicapped by the systems jargon that has developed in the literature. The communication problem is a major one, even for persons working in the same field. For the purposes of this paper, systems modelling is defined as an activity involving the construction of a mathematical model of a system, generally but not necessarily followed by manipulation or experimentation with the model. The model may simply describe the behaviour of the system over time or space (a simulation model), or it may be based on optimising techniques such as linear or dynamic programming. Systems modelling is part of what is variously referred to as systems analysis, systems research or the systems approach (Dale, 1970; Watt, 1966; Wright, 1973).