Water taken up through the bark is detected in the transpiration stream in intact upper‐canopy branches
2022
Gimeno, Teresa | Stangl, Zsofia | Barbeta, Adrià | Saavedra, Noelia | Wingate, Lisa | Devert, Nicolas | Marshall, John | Centre for Ecological Research and Applied Forestries = Centre de Recerca Ecologica i Aplicacions Forestals (CREAF) ; Consejo Superior de Investigaciones Cientificas [España] = Spanish National Research Council [Spain] (CSIC) | Department of Forest Ecology and Management ; Swedish University of Agricultural Sciences = Sveriges lantbruksuniversitet (SLU) | Universitat de Barcelona (UB) | Swedish University of Agricultural Sciences = Sveriges lantbruksuniversitet (SLU) | Interactions Sol Plante Atmosphère (UMR ISPA) ; Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
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Mostrar más [+] Menos [-]Inglés. Alternative water uptake pathways through leaves and bark complement water supply with interception, fog or dew. Bark water-uptake contributes to embolism-repair, as demonstrated in cut branches. We tested whether bark water-uptake could also contribute to supplement xylem-water for transpiration. We applied bandages injected with H-2-enriched water on intact upper-canopy branches of Pinus sylvestris and Fagus sylvatica in a boreal and in a temperate forest, in summer and winter, and monitored transpiration and online isotopic composition (delta H-2 and delta O-18) of water vapour, before sampling for analyses of delta H-2 and delta O-18 in tissue waters. Xylem, bark and leaf waters from segments downstream from the bandages were H-2-enriched whereas delta O-18 was similar to controls. Transpiration was positively correlated with H-2-enrichment. Isotopic compositions of transpiration and xylem water allowed us to calculate isotopic exchange through the bark via vapour exchange, which was negligible in comparison to estimated bark water-uptake, suggesting that water-uptake occurred via liquid phase. Results were consistent across species, forests and seasons, indicating that bark water-uptake may be more ubiquitous than previously considered. We suggest that water taken up through the bark could be incorporated into the transpiration stream, which could imply that sap-flow measurements underestimate transpiration when bark is wet.
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