Ecological Archives A025-145-A3

Ashehad A. Ali, Chonggang Xu, Alistair Rogers, Nathan G. McDowell, Belinda E. Medlyn, Rosie A. Fisher, Stan D. Wullschleger, Peter B. Reich, Jasper A. Vrugt, William L. Bauerle, Louis S. Santiago, and Cathy J. Wilson. 2015. Global-scale environmental control of plant photosynthetic capacity. Ecological Applications 25:23492365. http://dx.doi.org/10.1890/14-2111.1

Appendix C. Effect of temperature acclimation on leaf photosynthesis (A).

The most dramatic warming is predicted to occur for high latitudes (boreal and arctic) (Bonan 2008, Bader 2014, Ding et al. 2014). Therefore, the temperature effects on Vc,max25 could be important to predict vegetation responses to warming. We obtained the average values of the leaf nitrogen content and environmental conditions for boreal and arctic from our data set. The values of Vc,max25, Jmax25 were obtained using the complete linear mixed effects model of Vc,max25, Jmax25. Then we calculated the photosynthetic rate by using the Farquhar’s photosynthetic and the Ball-Berry model. We assumed that there is a 4 degree increase in leaf temperature compared to air temperature. The photosynthetic rates under current environmental conditions and under increased temperature were determined and the effect of temperature acclimation was explored. Specifically, the following was carried out.

The environmental conditions were typical of arctic and boreal regions (daytime radiation (R; 271.09 W m-2); daytime temperature (T; 14.56°C and 19.56°C); day length (D; 18.29 hours); and relative humidity (RH; 0.69)). The air pressure and CO2 level was considered as 100459.5 Pa, 393 ppm, respectively for arctic and boreal. Vc,max25, Jmax25 was considered as 91.6 µmol CO2 m-2 s-1, 205.7 µmol electron m-2 s-1, respectively at 14.56°C. These values of Vc,max25, Jmax25 were obtained using the complete linear mixed effects model of Vc,max25, Jmax25. To examine the effect of temperature acclimation on A, we first converted Vc,max25 and Jmax25 to Vc,max and Jmax, respectively, using TRF4 as the temperature dependence functions of Vc,max and Jmax (see Appendix E). Then we calculated the photosynthetic rate by using the Farquhar’s photosynthetic and the Ball-Berry model (shown in Appendix F), where equations of Wc and Wj as in version 1 (Eqns. F.3, F.4) were used (see Appendix F). We assumed that there is a 4 degree increase in leaf temperature compared to air temperature (Wilson 1957). In the case of without acclimation, Vc,max25 was held fixed; only temperature was varied, and the values of A were 16.95 µmol CO2 m-2 s-1, 20.3 µmol CO2 m-2 s-1 at 14.56°C, 23.56°C, respectively. In the case of with acclimation, the value of Vc,max25 at 23.56°C was 91.6µmol CO2 m-2 s-1 less 3.65%. (see the temperature coefficient from Fig. 3c). Next, the value of A at 23.56°C was obtained as 19.41µmol CO2 m-2 s-1. The effect of with/without temperature acclimation on A was then determined.

Literature cited

Bader, J. 2014. Climate science: The origin of regional Arctic warming. Nature 509:167-168.

Bonan, G. B. 2008. Forests and climate change: Forcings, feedbacks, and the cliamte benefits of forests. Science 320:1444-1449.

Ding, Q., J. M. Wallace, D. S. Battisti, E. J. Steig, A. J. E. Gallant, H.-J. Kim, and L. Geng. 2014. Tropical forcing of the recent rapid Arctic warming in northeastern Canada and Greenland. Nature 509:209-212.

Wilson, J. W. 1957. Observations on the temperatures of arctic plants and their environment. Journal of Ecology 45:499-531.


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