Dresden 2020 – scientific programme

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UP: Fachverband Umweltphysik

UP 4: Atmospheric Chemistry 1

UP 4.3: Talk

Tuesday, March 17, 2020, 15:40–16:00, HSZ 105

Ozone impact on plant physiology and nitrogen partitioning — •Stefanie Falk¹, Ane Victoria Vollsnes², Frode Stordal¹, and Terje Koren Berntsen¹ — ¹University of Oslo, Department of Geosciences — ²University of Oslo, Department of Biosciences

Ozone is an important trace gas in the Earth’s atmosphere. Stratospheric ozone protects all lifeforms on its surface from harmful UV radiation. In the boundary layer, ozone is regarded as a toxic pollutant and cause to an average global loss of yield in the four major crops of about 3−15 %. Future projections indicate that high ozone concentrations may affect food security in the future especially in Asia.
Ozone alters the plants photosynthesis through, e.g. reduction of CO₂ uptake (decrease in stomatal/ mesophyll conductance), processing of CO₂ (decrease in enzymes/proteins important for light capture, electron transport, and carboxylation), and enhancement in defense and repair reactions. A key determinant for photosynthesis is the concentration of leaf nitrogen. Each CO₂ processing step has a nitrogen cost associated.
In the absence of ozone, such a nitrogen cost model (LUNA in CLM5.0) has been shown to capture 55−65 % of the observed variation in the maximum electron transport rate J_max and maximum carboxylation rate V_cmax, respectively.
Based on data of deciduous trees from recent peer-reviewed articles, we establish a relationship between accumulative ozone dose (CUO) and the change in nitrogen cost for photosynthesis and show first results.