A Model of Calcium‐Cycling in An East Tennessee Liriodendron Forest: Model Structure, Parameters and Frequency Response Analysis
1976
Shugart, H. H., Jr | Reichle, D. E. | Edwards, N. T. | Kercher, J. R.
A 29—compartment model of the kinetics of calcium in an east Tennessee Liriodendron forest is developed. The model structure is based on the functional components of the Liriodendron forest determined after more than a decade of intensive studies on the structure and function of the forest. Parameters for the model and initial conditions for the state variables were determined from coordinated ecological studies in the Liriodendron forest. These studies included characterization of chemical pools, quantification of ecosystem processes and analyses of mineral transport dynamics using radioactive tracers. The calcium model was analyzed for stability and controlability using frequency response analysis, a classic control theory technique. The model was stable for each of the 29 possible feedback loops connecting an ecosystem monitoring point (e.g., Ca content of soil H₂O) to an input source (e.g., atmospheric deposition). Certain monitoring points in the system, although they resulted in stable responses, caused natural variations in the system input to be amplified. The results proscribe arbitrary assignment of components as ecosystem monitoring points, and identify this potential problem in ecosystem management.
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