Thermodynamics and ecology

Abstract

How to apply thermodynamic methods and concepts to ecology, how to describe the ecosystem's behaviour in terms of physics (and particularly, thermodynamics), what kind of physical criteria can be used for estimation of anthropogenic impact on ecosystems? — I try to answer these questions in this manuscript. From the viewpoint of thermodynamics, any ecosystem is an open system far from thermodynamic equilibrium, in which entropy production is balanced by the outflow of entropy to the environment. I suggest the ‘entropy pump’ hypothesis: the climatic, hydrological, soil and other environmental conditions are organised in such a way that only a natural ecosystem which is specific for these conditions can be in the dynamic equilibrium (steady-state). In the framework of this hypothesis I can calculate the entropy production for the ecosystem under anthropogenic stress. This approach was applied to the analysis of crop production in Hungary in the 1980s. Considering systems far from thermodynamic equilibrium we can prove that the so-called exergy is a functional of a dissipative function, which is undertaken along the trajectory from a thermodynamic equilibrium to a dynamic one. It was shown there is a close connection between the measure of additional information (Kullback's measure) and exergy.