Abstract :
[en] Trees remain sufficiently hydrated during drought by closing stomata and reducing canopy conductance (Gc ) in response to variations in atmospheric water demand and soil water availability. Thresholds that control the reduction of Gc are proposed to optimize hydraulic safety against carbon assimilation efficiency. However, the link between Gc and the ability of stem tissues to rehydrate at night remains unclear. We investigated whether species-specific Gc responses aim to prevent branch embolisms, or enable night-time stem rehydration, which is critical for turgor-dependent growth. For this, we used a unique combination of concurrent dendrometer, sap flow and leaf water potential measurements and collected branch-vulnerability curves of six common European tree species. Species-specific Gc reduction was weakly related to the water potentials at which 50% of branch xylem conductivity is lost (P50 ). Instead, we found a stronger relationship with stem rehydration. Species with a stronger Gc control were less effective at refilling stem-water storage as the soil dries, which appeared related to their xylem architecture. Our findings highlight the importance of stem rehydration for water-use regulation in mature trees, which likely relates to the maintenance of adequate stem turgor. We thus conclude that stem rehydration must complement the widely accepted safety-efficiency stomatal control paradigm.
Funding text :
RLP acknowledges the support of the Swiss National Science Foundation (SNSF), Grant P2BSP3_184475. MG acknowledges funding by Swiss National Science Foundation Project ICOS-CH Phase 3 20FI20_198227. FB acknowledges funding from the project ‘Inside out’ (#POIR.04.04.00-00-5F85/18-00) funded by the HOMING programme of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund. LD acknowledges the support provided by the Department of Environmental Sciences at the University of Basel and the Swiss Federal Office for the Environment (FOEN). RP acknowledges support by the grant RTI2018-095297-J-I00 (Spain). CG acknowledges funding by the Swiss National Science Foundation (310030_204697). We would also like to thank three anonymous reviewers for their generous time in providing detailed comments and suggestions, which helped us to improve the presented research.RLP acknowledges the support of the Swiss National Science Foundation (SNSF), Grant P2BSP3_184475. MG acknowledges funding by Swiss National Science Foundation Project ICOS‐CH Phase 3 20FI20_198227. FB acknowledges funding from the project ‘Inside out’ (#POIR.04.04.00‐00‐5F85/18‐00) funded by the HOMING programme of the Foundation for Polish Science co‐financed by the European Union under the European Regional Development Fund. LD acknowledges the support provided by the Department of Environmental Sciences at the University of Basel and the Swiss Federal Office for the Environment (FOEN). RP acknowledges support by the grant RTI2018‐095297‐J‐I00 (Spain). CG acknowledges funding by the Swiss National Science Foundation (310030_204697). We would also like to thank three anonymous reviewers for their generous time in providing detailed comments and suggestions, which helped us to improve the presented research.
Scopus citations®
without self-citations
8