title: Anthropogenic NOx emissions alter the intrinsic water-use efficiency (WUEi) for Quercus cerris stands under Mediterranean climate conditions.
abstract: We investigated the effect of N deposition (Ndep) on intrinsic water-use efficiency (WUEi), the ratio of photosynthesis (A) to stomatal conductance (gs), for two Quercus cerris stands at different distances to an oil refinery in Southern Italy. We used delta13C in tree rings for assessing changes in WUEi; while the influence of climate and NOx emission was explored through delta18O and delta15N, respectively. Differences in WUEi between the two sites were significant, with trees exposed to different degrees of NOx emissions showing an abrupt increase with the onset of pollution. Assuming similar gs at the two sites, as inferred through delta18O, the higher N availability at the polluted site caused the shift of the A/gs ratio in favour of A. Overall, our result suggests that an increase of Ndep may enhance tree WUE under a scenario of reduction of precipitation predicted for Mediterranean area.
authors.affiliation: Department of Crop Systems, Forestry and Environmental Sciences, University of Basilicata, Viale dell'Ateneo Lucano 10, I-85100 Potenza, Italy. Rosella.Guerrieri@ac.ed.uk
authors.forename: Rossella
authors.initials: R
authors.lastname: Guerrieri
authors.forename: Rolf
authors.initials: R
authors.lastname: Siegwolf
authors.forename: Matthias
authors.initials: M
authors.lastname: Saurer
authors.forename: Francesco
authors.initials: F
authors.lastname: Ripullone
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mencuccini
authors.forename: Marco
authors.initials: M
authors.lastname: Borghetti
mesh_terms: D002980:Climate; D004785:Environmental Pollutants / Q000032:analysis / Q000633:toxicity*; D009587:Nitrogen Isotopes / Q000378:metabolism; D009589:Nitrogen Oxides / Q000032:analysis / Q000633:toxicity*; D010103:Oxygen Isotopes / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D029963:Quercus / Q000187:drug effects* / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D009587:Nitrogen Isotopes; D009589:Nitrogen Oxides; D010103:Oxygen Isotopes; D014867:Water