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Anthropogenic NOx emissions alter the intrinsic water-use efficiency (WUEi) for Quercus cerris stands under Mediterranean climate conditions |
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| Authors: | Rossella Guerrieri Rolf Siegwolf Francesco Ripullone Marco Borghetti |
| Affiliation: | a Department of Crop Systems, Forestry and Environmental Sciences, University of Basilicata, Viale dell’Ateneo Lucano 10, I-85100 Potenza, Italy b Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland c School of Geosciences University of Edinburgh, Crew Building, The King’s Buildings, West Mains Road, Edinburgh EH9 3JN, United Kingdom |
| 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 δ13C in tree rings for assessing changes in WUEi; while the influence of climate and NOx emission was explored through δ18O and δ15N, 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 δ18O, 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. |
| Keywords: | Intrinsic water-use efficiency N deposition Stable C-N-O isotopes Tree rings Quercus cerris |
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