Do all ecosystems maximise their distance with respect to thermodynamic equilibrium? A comment on the "Ecological Law of Thermodynamics" (ELT), proposed by Sven Erik Jørgensen
Rutger de Wit

This paper is dedicated to the late Professor Ramon Margalef, deceased 23 May 2004, who pioneered the study of the links between ecology, thermodynamics and information theory. The personal kindness of Ramon Margalef, and his stimulating and thought-provocative way of teaching and discussing issues in ecology and natural sciences have been a great source of inspiration. Sven Erik Jørgensen has boldly proposed a “Fourth Law of Thermodynamics” which he also advocates as the “Ecological Law of Thermodynamics” or ELT (Integration of Ecosystem Theories: A Pattern, Kluwer Academic Publisher). This Law is still a hypothesis and can be tested. I disagree with the generalised way he uses the term “exergy” in his approach. Exergy is commonly defined as a measure of the work capacity of a system. According to the physicists Boltzmann information embodies energy. Jørgensen takes this into account when considering the “exergy” stored in ecosystems; hence, according to his way of calculating the genetic information of the organisms is the mayor contribution to “exergy”. I argue that energy has been embodied in the information during a historical process and that because of fundamental irreversibility this energy cannot be extracted again for work capacity. Moreover, other phenomena mentioned earlier by Ramon Margalef, demonstrate that proliferating information in biota shows uncoupling with respect to its embodied energy content according to the Boltzmann formula. In spite of these objections, some of Sven Erik Jørgensen’s core ideas are exiting and worthwhile testing. I place these within the context of the non-equilibrium thermodynamic theories on “dissipative systems” developed by the physicist Ilya Prigogine.

Keywords: exergy, information, Gibb’s free energy, embodied energy, genetic information.
Contents of this volume Sci. Mar. 69(3) : 427-434 Back PDF
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