Input signals for sampling and identification of ecological systems

The determination of a model relating structure and function of an ecosystem often results from an input-output tracer experiment. The different identification schemes that are available can be classified according to the basic elements of the modeling problem and the input signals, the earliest being those based on frequency, step, and impulse responses. Special inputs rather than those of normal operation are necessary for the off-line identification of tracer analysis. Radioactive tracers, as used in compartmental system studies, provide practical and basic experimental designs which coexist with theoretical techniques of data collection, sampling, theory, and model identification algorithms.