Pattern and Process in Ecological Systems: A Step in the Development of a General Ecological Theory

Abstract

The dominant fish populations in undisturbed arctic lakes are characterized as being in a state of "least specific dissipation": the greatest biomass attainable for a given energy input. A survey of autonomous ecosystems in various parts of the world indicated that this pattern is widespread. It is concluded that ecosystems are formed at the point of intersection of two established physical principles: the "principle of most action" (≈least dissipation or conservation of free energy) and the "principle of least action". "Action" is defined as the product of energy times time (joule-seconds). The trend to "most action" necessitates deceleration of energy flow: "least action" accelerates energy flow. For an ecosystem to survive over ecological time, the principle of most action must override the principle of least action. In that different species of organism have different capacities to conserve free energy (increase action), a hierarchy is formed locally in which action increases at each hierarchical level. Over the long term, as a result of genetic instability, both principles induce change, but the principle of least action dominates system behaviour causing increasingly rapid energy dissipation. Evolution is the resultant of these two countervailing forces.