Entropy budget of conifer branches

Abstract

From energy budget data for a branch of ponderosa pine given by Gates, Tibbals and Kreith, entropy fluxes into or out of the branch due to solar radiation, infrared radiation, transpiration and convection are calculated. Net entropy flow into the branch is negative. Assuming that the entropy in the branch is at steady state, the entropy production in the branch of ponderosa pine is calculated and shown to be positive. A positive entropy production indicates that the Second Law of Thermodynamics is certainly valid in the branch. Entropy productions in other conifers, blue spruce and white fir, and in a single pine needle in a horizontal position are also calculated. The entropy production (Sprod) increases linearly with the solar energy absorbed by the plant surface (Esolar); Sprod≈(30.6 Esolar)×10−4. The ratio (Sprod/Esolar) does not differ between deciduous leaves reported earlier and conifer branches. The theorem of oscillating entropy production proposed earlier holds also for conifer branches and will be of universal nature, applicable to all plant leaves.