Leaf temperature and its departure from ambient air temperature

Lian, X., Jiji, J., Fang, J., Han, J., Ryu, Y., Harrison, S. P. ORCID: https://orcid.org/0000-0001-5687-1903, Jeong, S., Zhang, H., Novick, K., Benson, M. C., Dong, N., Green, J. K., Sandoval, D., Liu, J., Keenen, T. and Gentine, P. (2026) Leaf temperature and its departure from ambient air temperature. Nature Plants, 12. pp. 1189-1202. ISSN 2055-0278 doi: 10.1038/s41477-026-02304-w

Abstract/Summary

Leaf temperature (Tl), the temperature at which leaf–air exchanges of carbon and water occur, varies with ambient air temperature (Ta), regulated by microclimate and species’ energy balance traits. Ground and satellite thermal measurements of the Tl–Ta relationship are widely used to infer plants’ thermoregulation capacity. On the basis of a global synthesis of observations across diverse climates and biomes, we show that reported thermoregulation patterns vary primarily along temperature gradients. Megathermy (dTl/dTa > 1) is particularly prevalent in warm tropical regions and in sun-exposed canopy-top leaves owing to ineffective dissipation of the often excessively accumulated solar radiation, while limited homeothermy (dTl/dTa < 1) and poikilothermy (dTl/dTa = 1) are reported mostly for cold ecosystems or sub-canopy leaves. Under heat-stressed conditions, some warm-adapted species can abate rapid Tl surge through active stomatal control, unless critical temperature thresholds are exceeded, above which Tl might increase non-linearly as a warning sign of damaging stress. This thermal consideration of stomatal regulation is currently missing in mechanistic models as a source of bias in estimated photosynthetic rates. We highlight the pressing need to develop new stomatal theories that tackle a triple-target optimization between carbon gain, water loss and thermal regulation.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/130676
Identification Number/DOI	10.1038/s41477-026-02304-w
Refereed	Yes
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Publisher	Nature Publishing Group
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