title: Impact of elevated CO2 concentration on dynamics of leaf photosynthesis in Fagus sylvatica is modulated by sky conditions.
abstract: It has been suggested that atmospheric CO2 concentration and frequency of cloud cover will increase in future. It remains unclear, however, how elevated CO2 influences photosynthesis under complex clear versus cloudy sky conditions. Accordingly, diurnal changes in photosynthetic responses among beech trees grown at ambient (AC) and doubled (EC) CO2 concentrations were studied under contrasting sky conditions. EC stimulated the daily sum of fixed CO2 and light use efficiency under clear sky. Meanwhile, both these parameters were reduced under cloudy sky as compared with AC treatment. Reduction in photosynthesis rate under cloudy sky was particularly associated with EC-stimulated, xanthophyll-dependent thermal dissipation of absorbed light energy. Under clear sky, a pronounced afternoon depression of CO2 assimilation rate was found in sun-adapted leaves under EC compared with AC conditions. This was caused in particular by stomata closure mediated by vapour pressure deficit.
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic. Electronic address: urban.o@czechglobe.cz.
authors: Otmar
authors: O
authors: Urban
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic.
authors: Karel
authors: K
authors: Klem
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic.
authors: Petra
authors: P
authors: Holišová
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic; Faculty of Science, University of Ostrava, 30. dubna 22, CZ-70103 Ostrava 1, Czech Republic.
authors: Ladislav
authors: L
authors: Šigut
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic.
authors: Mirka
authors: M
authors: Šprtová
authors: Faculty of Science, University of Ostrava, 30. dubna 22, CZ-70103 Ostrava 1, Czech Republic.
authors: Petra
authors: P
authors: Teslová-Navrátilová
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic.
authors: Martina
authors: M
authors: Zitová
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic; Faculty of Science, University of Ostrava, 30. dubna 22, CZ-70103 Ostrava 1, Czech Republic.
authors: Vladimír
authors: V
authors: Špunda
authors: Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 4a, CZ-60300 Brno, Czech Republic.
authors: Michal V
authors: MV
authors: Marek
authors: Institute of Atmospheric and Environmental Science, School of GeoSciences, University of Edinburgh, The Kings Buildings, Edinburgh EH9 3JN, UK.
authors: John
authors: J
authors: Grace
mesh_terms: D000393:Air Pollutants / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D029964:Fagus / Q000502:physiology*; D008027:Light; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D014887:Weather; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D000393:Air Pollutants; D024341:Xanthophylls; D002245:Carbon Dioxide
keywords: DEPS; Diurnal dynamics; European beech; Fluorescence; Photorespiration; Stomatal conductance; Xanthophylls