Comparison of leaf water use efficiency of oak and sycamore in the canopy over two growing seasons

Stokes, Victoria J.; Morecroft, Michael D.; Morison, James I.L.. 2010 Comparison of leaf water use efficiency of oak and sycamore in the canopy over two growing seasons. Trees - Structure and Function, 24 (2). 297-306.

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The seasonal trends in water use efficiency of sun and shade leaves of mature oak (Quercus robur) and sycamore (Acer pseudoplatanus) trees were assessed in the upper canopy of an English woodland. Intrinsic water use efficiency (net CO2 assimilation rate/leaf conductance, A/g) was measured by gas exchange and inferred from C isotope discrimination (δ13C) methods. Shade leaves had consistently lower δ13C than sun leaves (by 1–2‰), the difference being larger in sycamore. Buds had distinct sun and shade isotopic signatures before bud break and received an influx of 13C-rich C before becoming net autotrophs. After leaf full expansion, δ13C declined by 1–2‰ gradually through the season, emphasising the importance of imported carbon in the interpretation of leaf δ13C values in perennial species. There was no significant difference between the two species in the value of intrinsic water use efficiency for either sun or shade leaves. For sun leaves, season-long A/g calculated from δ13C (72–78 μmol CO2 [mol H2O]−1) was 10–16% higher than that obtained from gas exchange and in situ estimates of leaf boundary layer conductance. For shade leaves, the gas exchange–derived values were low, only 10–18% of the δ13C-derived values. This is ascribed to difficulties in obtaining a comprehensive sample of gas exchange measurements in the rapidly changing light environment.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry > CC01B Land-surface Feedbacks in the Climate System > CC01.6 Development of the Joint Unified Land Exchange Scheme (JULES) land-surface model
CEH Topics & Objectives 2009 - 2012 > Biogeochemistry
UKCEH and CEH Sections/Science Areas: Pywell
ISSN: 0931-1890
Additional Information. Not used in RCUK Gateway to Research.: The original publication is available at
NORA Subject Terms: Ecology and Environment
Date made live: 26 Apr 2010 15:18 +0 (UTC)

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