Development of models able to account for changes in species composition

Our present modelling approach uses constant parameters and therefore does not account for changes in properties within the same species or even for shifts to other species with significantly different properties. A modelling approach using currently changing parameters in accordance with a goal function is introduced in this paper. As goal function 'energy = biogeochemical energy of the system' is used. It can be considered as a translation of Darwin's theory ('survival of the fittest') to thermodynamics. The proposed approach has now been used successfully on four case studies. One was published (Jørgensen, 1986) and three other cases are presented in this paper.