title: Canopy-level stomatal narrowing in adult Fagus sylvatica under O3 stress - means of preventing enhanced O3 uptake under high O3 exposure?
abstract: Spatio-temporally consistent O(3) doses are demonstrated in adult Fagus sylvatica from the Kranzberg Forest free-air fumigation experiment, covering cross-canopy and whole-seasonal scopes through sap flow measurement. Given O(3)-driven closure of stomata, we hypothesized enhanced whole-tree level O(3) influx to be prevented under enhanced O(3) exposure. Although foliage transpiration rate was lowered under twice-ambient O(3) around noon by 30% along with canopy conductance, the hypothesis was falsified, as O(3) influx was raised by 25%. Nevertheless, the twice-ambient/ambient ratio of O(3) uptake was smaller by about 20% than that of O(3) exposure, suggesting stomatal limitation of uptake. The O(3) response was traceable from leaves across branches to the canopy, where peak transpiration rates resembled those of shade rather than sun branches. Rainy/overcast-day and nightly O(3) uptake is quantified and discussed. Whole-seasonal canopy-level validation of modelled with sap flow-derived O(3) flux becomes available in assessing O(3) risk for forest trees.
authors: Ecophysiology of Plants, Technische Universität München, von-Carlowitz-Platz 2, D-85354 Freising, Germany. Electronic address: matyssek@wzw.tum.de.
authors: R
authors: R
authors: Matyssek
authors: Ecophysiology of Plants, Technische Universität München, von-Carlowitz-Platz 2, D-85354 Freising, Germany.
authors: M
authors: M
authors: Baumgarten
authors: Ecophysiology of Plants, Technische Universität München, von-Carlowitz-Platz 2, D-85354 Freising, Germany.
authors: U
authors: U
authors: Hummel
authors: Ecophysiology of Plants, Technische Universität München, von-Carlowitz-Platz 2, D-85354 Freising, Germany.
authors: K-H
authors: KH
authors: Häberle
authors: Department of Plant Ecology, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan.
authors: M
authors: M
authors: Kitao
authors: Department of Alpine Timberline Ecophysiology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape (BFW), Rennweg 1, 6020 Innsbruck, Austria.
authors: G
authors: G
authors: Wieser
mesh_terms: D000388:Air; D000393:Air Pollutants / Q000378:metabolism / Q000633:toxicity*; D004777:Environment; D029964:Fagus / Q000502:physiology*; D005651:Fumigation; D018384:Oxidative Stress; D010126:Ozone / Q000378:metabolism / Q000633:toxicity*; D010788:Photosynthesis; D018515:Plant Leaves / Q000737:chemistry; D011891:Rain; D013472:Sunlight; D014197:Trees
chemical_list: D000393:Air Pollutants; D010126:Ozone
keywords: Canopy conductance; Fagus sylvatica; Growing season; Ozone dose; Stomata