99419 20210902121828.0 doi 10.1093/treephys/tpaa026 sideral 118333 ART-2020-118333 eng Ripullone, F. Variation in the access to deep soil water pools explains tree-to-tree differences in drought-triggered dieback of Mediterranean oaks 2020 Access copy available to the general public Unrestricted Individual differences in the access to deep soil water pools may explain the differential damage among coexisting, conspecific trees as a consequence of drought-induced dieback. We addressed this issue by comparing the responses to a severe drought of three Mediterranean oak species with different drought tolerance, Quercus pubescens L. and Quercus frainetto Ten., mainly thriving at xeric and mesic sites, respectively, and Quercus cerris L., which dominates at intermediate sites. For each species, we compared coexisting declining (D) and non-declining (ND) trees. The stable isotope composition (d2H, d18O) of xylem and soil water was used to infer a differential use of soil water sources. We also measured tree size and radial growth to quantify the long-term divergence of wood production between D and ND trees and non-structural carbohydrates (NSCs) in sapwood to evaluate if D trees presented lower NSC values. The ND trees had access to deeper soil water than D trees except in Q. frainetto, as indicated by significantly more depleted xylem water values. However, a strong d2H offset between soil and xylem water isotopes observed in peak summer could suggest that both tree types were not physiologically active under extreme drought conditions. Alternative processes causing deuterium fractionation, however, could not be ruled out. Tree height and recent (last 15-25 years) growth rates in all species studied were lower in D than in ND trees by 22 and 44%, respectively. Lastly, there was not a consistent pattern of NSC sapwood concentration; in Q. pubescens, it was higher in ND trees while in Q. frainetto, the D trees were the ones exhibiting the higher NSC concentration. We conclude that the vulnerability to drought among conspecific Mediterranean oaks depends on the differential access to deep soil water pools, which may be related to differences in rooting depth, tree size and growth rate. info:eu-repo/grantAgreement/ES/MINECO/CGL2015-69186-C2-1-R info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 4.196 2020 FORESTRY 4 / 67 = 0.06 2020 Q1 T1 1.413 2020 Plant Science 2020 Q1 Physiology 2020 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Camarero, J.J. (orcid)0000-0003-2436-2922 Colangelo, M. Voltas, J. 40, 5 (2020), 591-604 Tree physiol. Tree physiology 0829-318X 831320 http://zaguan.unizar.es/record/99419/files/texto_completo.pdf Postprint 1004230 http://zaguan.unizar.es/record/99419/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:99419 articulos driver 2021-09-02-10:13:41 ARTICLE