Sensitivity Analyses of the ELM Model

The sensitivity of an ecosystem simulation model, ELM, to variation in parameter values is studied by perturbing parameters in groups defined by a fractional factorial design followed by perturbing parameters singly and by calculating partial derivatives according to the method of Tomovic. Four output variables are used as sensitivity indicators. Total actual evapotranspiration is not very sensitive to any of the 68 parameters studied. The consumer models exhibit a few sensitivities, while net primary productivity and soil respiration are sensitive to a variety of parameters. In some cases particular parameters to which the model is sensitive are identified. The model shows several sensitivities expected on the basis of knowledge of the grassland ecosystem.