Plant resistance to drought depends on timely stomatal closure

• Published in: Ecology letters Vol. 20; no. 11; pp. 1437 - 1447
• Main Authors: Martin‐StPaul, Nicolas, Delzon, Sylvain, Cochard, Hervé, Maherali, Hafiz
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-11-2017; Wiley
• Subjects: Atmospheric models; Carbon cycle; Computer simulation; Dieback; Drought; Droughts; Embolism; Embolisms; Hydraulics; Life Sciences; Plant Leaves - physiology; Plant Physiological Phenomena; Plant resistance; Plant Stomata - physiology; Plant Transpiration; Safety margins; Stomata; Stress, Physiological; Transpiration; tree mortality; Water - physiology; Water potential; Xylem; Xylem - physiology; xylem embolism; stomata; tree mortality; xylem embolism; drought; Dieback; dynamique temporelle; metaanalysis; résistance à la sécheresse; plante résistante; storage stability; modélisation hydraulique; trait fonctionnel; résistance stomatique; aptitude à la conservation; méta analyse
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/ele.12851

Stomata play a significant role in the Earth's water and carbon cycles, by regulating gaseous exchanges between the plant and the atmosphere. Under drought conditions, stomatal control of transpiration has long been thought to be closely coordinated with the decrease in hydraulic capacity (hydraulic failure due to xylem embolism). We tested this hypothesis by coupling a meta‐analysis of functional traits related to the stomatal response to drought and embolism resistance with simulations from a soil–plant hydraulic model. We report here a previously unreported phenomenon: the existence of an absolute limit by which stomata closure must occur to avoid rapid death in drought conditions. The water potential causing stomatal closure and the xylem pressure at the onset of embolism formation were equal for only a small number of species, and the difference between these two traits (i.e. safety margins) increased continuously with increasing embolism resistance. Our findings demonstrate the need to revise current views about the functional coordination between stomata and hydraulic traits and provide a mechanistic framework for modeling plant mortality under drought conditions.