RT Journal Article
SR Electronic
T1 Processes driving nocturnal transpiration and implications for estimating land evapotranspiration
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 017202
DO 10.1101/017202
A1 Vίctor Resco de Dios
A1 Jacques Roy
A1 Juan Pedro Ferrio
A1 Josu G. Alday
A1 Damien Landais
A1 Alexandru Milcu
A1 Arthur Gessler
YR 2015
UL http://biorxiv.org/content/early/2015/03/30/017202.abstract
AB Evapotranspiration is a major component of the water cycle, yet only daytime transpiration is currently considered in Earth system and agricultural sciences. This contrasts with physiological studies where 25% or more of water losses have been reported to occur occurring overnight at leaf and plant scales. This gap probably arose from limitations in techniques to measure nocturnal water fluxes at ecosystem scales, a gap we bridge here by using lysimeters under controlled environmental conditions. The magnitude of the nocturnal water losses (12-23% of daytime water losses) in row-crop monocultures of bean (annual herb) and cotton (woody shrub) would be globally an order of magnitude higher than documented responses of global evapotranspiration to climate change (51-98 vs. 7-8 mm yr−1). Contrary to daytime responses and to conventional wisdom, nocturnal transpiration was not affected by previous radiation loads or carbon uptake, and showed a temporal pattern independent of vapour pressure deficit or temperature, because of endogenous controls on stomatal conductance via circadian regulation. Our results have important implications from large-scale ecosystem modelling to crop production: homeostatic water losses justify simple empirical predictive functions, and circadian controls show a fine-tune control that minimizes water loss while potentially increasing posterior carbon uptake.