title: Deriving ozone dose-response of photosynthesis in adult forest trees from branch-level cuvette gas exchange assessment.
abstract: Branch-level gas exchange provided the basis for assessing ozone flux in order to derive the dose-response relationship between cumulative O3 uptake (COU) and carbon gain in the upper sun crown of adult Fagus sylvatica. Fluxes of ozone, CO2 and water vapour were monitored simultaneously by climatized branch cuvettes. The cuvettes allowed branch exposure to an ambient or twice-ambient O3 regime, while tree crowns were exposed to the same O3 regimes (twice-ambient generated by a free-air canopy O3 exposure system). COU levels higher than 20mmolm(-2) led to a pronounced decline in carbon gain under elevated O3. The limiting COU range is consistent with findings on neighbouring branches exposed to twice-ambient O3 through free-air fumigation. The cuvette approach allows to estimate O3 flux at peripheral crown positions, where boundary layers are low, yielding a meso-scale within-crown resolution of photosynthetic foliage sensitivity under whole-tree free-air O3 fumigation.
authors.affiliation: Unit of Alpine Timberline Ecophysiology, Federal Office and Research Centre for Forests, Rennweg 1, A-6020 Innsbruck, Austria. christiane.then@uibk.ac.at
authors.forename: C
authors.initials: C
authors.lastname: Then
authors.forename: M
authors.initials: M
authors.lastname: Löw
authors.forename: R
authors.initials: R
authors.lastname: Matyssek
authors.forename: G
authors.initials: G
authors.lastname: Wieser
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D002245:Carbon Dioxide / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D029964:Fagus / Q000187:drug effects / Q000378:metabolism*; D005858:Germany; D010083:Oxidants, Photochemical / Q000032:analysis / Q000633:toxicity*; D010126:Ozone / Q000032:analysis / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism
chemical_list: D000393:Air Pollutants; D010083:Oxidants, Photochemical; D002245:Carbon Dioxide; D010126:Ozone