Howard T. Odum - Ecological Modeling - Ecological Analog of Ohm's Law

Ecological Analog of Ohm's Law

In the 1950s Odum introduced his electrical circuit diagrams of ecosystems to the Ecological Society of America. He claimed that energy was driven through ecological systems by an "ecoforce" analogous to the role of voltage in electrical circuits.

Odum developed an analogue of Ohm's Law which aimed to be a representation of energy flows through ecosystems. In terms of steady state thermodynamics, Ohm's Law can be considered a special case of a more general flux law, where the flux "is proportional to the driving thermodynamic force with conductivity . That is: .

Kangas states that Odum then also concluded that as thermodynamic systems, ecosystems should also obey the force-flux law. Hence Ohm's law and passive electrical analog circuits can be used to simulate ecosystems (Ibid.). In this simulation, Odum attempted to derive an ecological analog for electrical voltage. Voltage, or driving force, is related to something we have measured for years, the biomass, in pounds per acre. The analogous concept required is the biomass activity, that is, the thermodynamic thrust, which may be linear. Exactly what this is in nature is still uncertain, as it is a new concept.

Such a consideration led Odum to ask two important methodological questions: 1) What is the electrical significance of a function observed in nature? 2) Given an electrical unit in a circuit, what is it in the ecological system? For example, what is a diode in nature? One needs a diode to allow biomass to accumulate after the voltage of the sun has gone down. Otherwise the circuit reverses. Higher organisms like fish are diodes.