Entropy and exergy are the central concepts in thermodynamics, and many researchers have used them to characterize ecosystem development. However, quantitative analysis of the relationship among exergy destruction, canopy surface temperature, and net radiation from the view of thermodynamic laws has rarely been conducted.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) analyzed the relationship among entropy production (exergy destruction), net radiation, and canopy surface temperature based on thermodynamic laws, and verified it with long-term monitoring data of Xishuangbanna tropical seasonal rain forest. They aimed to further understand the relationships between thermodynamic concepts and ecological indicators, i.e. net radiation and canopy surface temperature.
Generally, the specific entropy production was lower during the rainy season and higher during the dry season of the tropical seasonal rain forest. It decreased from April and reached the lowest level during August and September. The entropy budget of the forest was positive and stable throughout the year.
The empirical data showed that entropy production decreased linearly with increasing canopy surface temperature, and that higher incoming shortwave radiation produced more entropy. Entropy production linearly increased with net radiation Total entropy production increased, but specific entropy production reduced with forest growth.
The results showed that exergy destruction, entropy production, net radiation, and surface temperature are highly correlated. As compared with exergy destruction and entropy production, net radiation and canopy surface temperature are more perceivable.
Moreover, the measurements of net radiation and canopy surface temperature are more direct and accurate than those of the related indicators of entropy and exergy.