DEVELOPMENT OF A CHAMBER SYSTEM (ENTRON) FOR MEASURING ENTROPY PRODUCTION OF PLANTS

摘要

The first law of thermodynamics (heat balance) has been successfully applied to ecosystem studies and has brought about fruitful results on, for example, the mechanisms of microclimate within and above ecosystems. However, the second law of thermodynamics, which is closely related to entropy, has been almost ignored, except for some pioneering studies. Recently, the number of ecosystem studies based on the second law has increased and shows high potential for second law applications to ecosystem analyses, which might lead to disclosing what would not have been found without the second law standpoint However, many of ecosystem studies based on the second law are liable to fall into ideological arguments without any support from actual data. To overcome ideological arguments, and as a first step, this study aimed at developing a chamber system, called ENTRON, that could measure the 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. Thus, evaluated entropy production in the case of the empty chamber (no plants within it) could be regarded as the measurement error of ENTRON. Compared to this error, entropy production calculated by ENTRON in the case of plants within it showed significantly larger values. Most of the entropy production in the case of plants within ENTRON could be attributed to that associated with evapotranspiration. Knowledge obtained through ENTRON experiments will be applied to entropy production evaluation in natural and/or agricultural ecosystems. For example, we can obtain knowledge as to which terms in the entropy balance equation are important and which are negligible, through ENTRON experiments, and such knowledge will significantly reduce required efforts to evaluate entropy production in natural and agricultural ecosystems.