Based on the optimality concept, Dr. Han Wang and her coauthors (Owen Atkin, Trevor Keenan, Nick Smith, Ian Wright, Jens Kettge, Keith Bloonfield, Peter Reich and Colin Prentice) proposed a novel theory on leaf respiration acclimation that are largely neglected, but can be directly implemented, in the state-of-the-art land surface models. By assuming that leaf dark respiration is mainly for maintaining the maximum capacity of Rubisco carboxylation, they successfully extended the coordination hypothesis on photosynthesis (Chen, Reynolds, Harley, & Tenhunen, 1993) to explain why after acclimation or adaptation the response of leaf respiration in field plants to their growth temperature (ca. 3.5% K–1) is less steeper than their instantaneous thermal response at a time scale of minutes to hours (ca. 8.1% K–1).
Their answer is quite simple! Because the optimal respiration is to maximize the net photosynthetic carbon gain. Consequently, its thermal response at a weekly to monthly scale is not determined by the kinetics of Rubisco enzyme, but actually by the balance between the kinetic of Michaelis-Menten coefficient and photorespiration. The thermal acclimation at a long time scale can be realised by reducing the quantity of the relevant enzyme, which is usually represented by the rate at a standard temperature. This theoretical deduction and the generated quantitative predictions on thermal sensitivities of carboxylation capacity and dark respiration are supported by extensive field observations from the GlopResp dataset (Atkin et al., 2017) and the LCE dataset (Smith & Dukes, 2017)
As a major component of the carbon cycle, plant respiration releases carbon six times more than anthropogenic CO2 emissions from all sources combined. About half respiration is due to dark respiration in leaves, therefore thermal acclimation of leaf respiration can play an important role in alleviate the positive feedback between global warming and carbon cycle. Further work is required on implementing those acclimation processes in Earth System Models and quantify its role in our earth system.
References
Atkin, O. K., Bloomfield, K. J., Bahar, N. H., Griffin, K. L., Heskel, M. A., Huntingford, C., . . . Turnbull, M. H. (2017). Leaf Respiration in Terrestrial Biosphere Models. In G. Tcherkez. (Ed.), Advances in Photosynthesis and Respiration: Plant Respiration. (pp. In Press (doi.org/10.1007/1978-1003-1319-68703-68702_68706). ). Netherlands: Springer-Nature.
Chen, J.-L., Reynolds, J. F., Harley, P. C., & Tenhunen, J. D. (1993). Coordination theory of leaf nitrogen distribution in a canopy. Oecologia, 93, 63-69.
Smith, N. G., & Dukes, J. S. (2017). LCE: leaf carbon exchange data set for tropical, temperate, and boreal species of North and Central America. Ecology, 98(11), 2978-2978.