RT Journal Article T1 Nutritional status of Quercus suber populations under contrasting tree dieback A1 Morillas Viñuales, Lourdes A1 Gallardo, Antonio A1 Covelo Núñez, Felisa K1 Quercus suber K1 Tree dieback AB ‘Los Alcornocales’ Natural Park (southwest Spain), one of the most important Mediterranean cork oak (Quercus suber) forests in Europe, has experienced a substantial tree dieback in the past decades. We hypothesize that areas experiencing high eutrophication should exhibit higher leaf nitrogen (N) concentrations and lower N resorption efficiency and proficiency indices than areas under lower environmental stress, and this could be related with forest functioning and tree mortality rates. To test this hypothesis, we collected leaf and soil samples from four plots in the southern part of the park, near a polluted industrial area, and four plots in the northern part of the park, far from this pollution source. N and phosphorus (P) in green and senescent leaves and soil NH4+-N, NO3−-N and PO43−-P were analysed. Foliar N and the leaf N:P ratio were significantly higher in the southern plots (high-mortality plots) than in the northern plots. The resorption efficiency was significantly higher for P than for N in all southern and northern plots. The values of resorption proficiency indicated incomplete resorption for N and complete resorption for P in all plots. Our results suggest that oak populations showing high-mortality rates may be associated with tree N and P imbalance. PB Oxford University Press YR 2012 FD 2012 LK https://hdl.handle.net/10433/22897 UL https://hdl.handle.net/10433/22897 LA en NO L. Morillas, A. Gallardo, M. Portillo-Estrada, F. Covelo, Nutritional status of Quercus suber populations under contrasting tree dieback, Forestry: An International Journal of Forest Research, Volume 85, Issue 3, 3 July 2012, Pages 369–378, https://doi.org/10.1093/forestry/cps035 NO Ministerio Español de Ciencia e Innovación of the Spanish government (CGL2006-13665-C02-01, CGL2010-21381) NO Departamento de Sistemas Físicos, Químicos y Naturales DS RIO RD May 9, 2026