Nitrogen availability does not affect ozone flux-effect relationships for biomass in birch (Betula pendula) saplings

Dai, Lulu; Hayes, Felicity; Sharps, Katrina; Harmens, Harry; Mills, Gina. 2019 Nitrogen availability does not affect ozone flux-effect relationships for biomass in birch (Betula pendula) saplings. Science of the Total Environment, 660. 1038-1046.

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To investigate whether nitrogen (N) load affects the ozone (O3) stomatal flux-effect relationship for birch biomass, three-year old birch saplings were exposed to seven different O3 profiles (24 h mean of 35–66 ppb) and four different N loads (10, 30, 50 and 70 kg ha−1 yr−1) in precision-controlled hemispherical glasshouses (solardomes) in 2012 and 2013. Stomatal conductance (gs) under optimal growth conditions was stimulated by enhanced N supply but was not significantly affected by enhanced O3 exposure. Birch root, woody (stem + branches) and total biomass (root + woody) were not affected by the Phytotoxic Ozone Dose (POD1SPEC) after two seasons of O3 exposure, and enhanced N supply stimulated biomass production independent of POD1SPEC (i.e. there were no POD1SPEC × N interactions). There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment, which was not affected by O3 exposure or N load. Enhanced N supply stimulated the stem cross-sectional area at the end of season 2, but not at the end of season 1, which suggests a time lag before tree biomass responded to enhanced N supply. There was no significant effect of POD1SPEC on stem cross-sectional area after either the first or second growing season of the experiment. Contrasting results reported in the literature on the interactive impacts of O3 and N load on tree physiology and growth are likely due to species-specific responses, different duration of the experiments and/or a limitation of the number of O3 and N levels tested.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Soils and Land Use (Science Area 2017-)
UKCEH Fellows
ISSN: 0048-9697
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - full text available via Official URL link.
Additional Keywords: biomass, phytotoxic ozone dose, stomatal conductance, root cross-sectional area, Solardome
NORA Subject Terms: Agriculture and Soil Science
Atmospheric Sciences
Date made live: 26 Feb 2019 16:45 +0 (UTC)

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