Development of a chamber system to measure entropy balance of artificial ecosystems

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The First Law of Thermodynamics (heat balance) has been successfully applied to ecosystem studies and has brought about fruitful results on e.g., mechanism of microclimate within and above the ecosystems. On the contrary, the Second Law of Thermodynamics, which is closely related to entropy, has almost been ignored, except for some pioneering studies. This study aimed at developing a chamber system, called ENTRON, which could measure entropy production rate of plants within the chamber.ENTRON measured mass inflow, mass outflow, energy inflow and energy outflow into and out of the chamber. From these measurements entropy inflow and outflow were calculated and the entropy production within the chamber was evaluated based on the entropy balance of the space within the chamber. No measurements are free from errors, and ENTRON's error percentage in entropy production evaluation was about 5%. Most of entropy production in the case of plants within it could be attributed to that associated with evapotranspiration. ENTRON will be a powerful tool to analyze entropy production characteristics of plants. Based on the knowledge acquired from ENTRON experiments, entropy balance at natural ecosystems were evaluated. In some cases upwards longwave radiation was also important in the entropy balance.