The capacity of plant species to cope with increasing growth temperature is one of the key determinants in range shifts and local extinction of species. This response to temperature may vary geographically, due to genetic adaptation (evolved traits) to climate, and temporally, due to acclimation (reversible adjustment in the short-term temperature response) to changes in ambient temperature.

As a result, the temperature response of photosynthesis is one of the key factors that determines the predicted response to warming in global vegetation models. However, presently models lack a robust quantitative framework to represent acclimation and adaptation of photosynthetic temperature responses.

We quantified and modelled the key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves. This included data from 141 species from tropical rainforest to Arctic tundra.

We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets.

The observed global variation in the temperature optimum for photosynthesis was primarily explained by biochemical limitations to photosynthesis.

We found acclimation to growth temperature to be a stronger driver of this variation, than adaptation to temperature at climate of origin.

We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy.

This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

  • Paper: Kumarathunge, D. P., Medlyn, B. E., Drake, J. E., Tjoelker, M. G., Aspinwall, M. J., Battaglia, M. , Cano, F. J., Kelsey, C. R., Cavaleri, M. A., Cernusak, L. A., Chambers, J. Q., Crous, K. Y., De Kauwe, M. G., Dillaway, D. N., Dreyer, E. , Ellsworth, D. S., Ghannoum, O. , Han, Q. , Hikosaka, K. , Jensen, A. M., Kelly, J. W., Kruger, E. L., Mercado, L. M., Onoda, Y. , Reich, P. B., Rogers, A. , Slot, M. , Smith, N. G., Tarvainen, L. , Tissue, D. T., Togashi, H. F., Tribuzy, E. S., Uddling, J. , Vårhammar, A. , Wallin, G. , Warren, J. M. and Way, D. A. (2018), Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale. New Phytologist, in press, doi: 10.111/nph.15668.