Xylem safety in relation to the stringency of plant water potential regulation of European beech, Norway spruce, and Douglas-fir trees during severe drought

• DOI: 10.1007/s00468-024-02499-5
• Publication Date: 2024-03-23T16:01:41Z
• Authors: Katja Schumann; Bernhard Schuldt; Miriam Fischer; Christian Ammer; Christoph Leuschner
• Keywords: Douglas fir

Abstract Key message Norway spruce operates with larger hydraulic safety margins (HSM) than beech and Douglas-fir despite the known drought sensitivity of spruce, questioning a pivotal role HSM in tolerance. The exceptional 2018/2019 exposed Central Europe’s forests to severe stress, highlighting need better understand stomatal regulation strategies their relationship xylem under extreme drought. We studied diurnal, seasonal, inter-annual variation conductance ( g s ) leaf water potential Ψ Leaf co-occurring European F. sylvatica ), P. abies menziesii trees two summers related them traits characterizing resistance. In 2018, exhibited continuous decline from June September, as is characteristic for an anisohydric strategy, while closed stomata early reached least negative -values at end summer. showed low close P 12 (the pressure onset embolism) already July. Both conifers when approaching maintained -levels throughout summer, indicative isohydric regulation. 2019, all three species linear , but crossed contrast conifers. similar potentials turgor loss point (− 2.44 − 2.51 MPa) branch 50 (xylem 50% conductance; 3.3 3.8 MPa). Yet, operated smaller (HSM means: 0.79 0.77 (1.28 reduced size specific area 2019 increased Huber value. Our comparison during contradicts general assumption that operate HSMs angiosperm trees. Contrary expectation, appeared hydraulically less vulnerable Douglas-fir.