BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/354336

© 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/bync/4.0/)., Spatial and temporal variation in functional traits allows trees to adjust to shifting environmental conditions such as water stress. However, the change of traits, both mean and variances, along water availability gradients and across growing seasons, as well as their covariation with tree performance, have been rarely assessed. We examined intraspecific trait variation in coexisting evergreen (Quercus ilex ssp. ilex and Q. ilex ssp. ballota) and deciduous (Quercus faginea and Quercus humilis) Mediterranean oaks along a wide water availability gradient in northeastern Spain during six years. We measured leaf area (LA), shoot twig mass (Sm), leaf mass per area (LMA) and the ratio of shoot twig to leaf biomass (Sm:Lm). We characterized tree performance through basal area increment (BAI) and drought resilience indices. Higher variation was found within individuals than between individuals across populations and years. Within species, we found trait adjustments toward more conservative water-use (low LA and Sm and high LMA) with increasing drier conditions. Intraspecific trait variation was constrained by water availability, particularly on the deciduous species. In Q. ilex, trait variance of LMA positively covaried with annual BAI, whereas variance of LA, Sm and Sm:Lm was positively related to resistance and resilience against the severe 2012 drought in deciduous oaks. Our results support a tradeoff between the ability to tolerate drought and the capacity to cope with unpredictable changes in the environment through increased intraspecific trait variation, which may have implications on tree performance in the face of increased extreme events., EGA is supported by CSIC (PIE-20223AT003). XSM is supported by “Juan de la Cierva – Formación” fellowship from the Spanish MICINN (FJC2021-047175-I). AG was supported by the “Ramón y Cajal” Program of the Spanish MICINN (RyC2020- 030647-I) and by CSIC (PIE-20223AT003). BFM is supported by RYC2021-031321-I grant funded by MCIN/AEI /10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. AA is a Serra Húnter fellow. JJC thanks the support of project “Factores climáticos y de crecimiento que determinan el secuestro de carbono en la carrasca (Quercus ilex subsp. ballota) y el quejigo (Quercus faginea) en condiciones mediterráneas” financed by INIA (2007–2010). This research was funded by the Science and Innovation Ministry and the AEI with projects PID2021-123675OB-C43 and TED2021-129770B-C21., Peer reviewed