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- Title
Within-canopy and ozone fumigation effects on δ13C and Δ18O in adult beech (Fagus sylvatica) trees: relation to meteorological and gas exchange parameters.
- Authors
GESSLER, ARTHUR; LÖW, MARKUS; HEERDT, CHRISTIAN; DE BEECK, MAARTEN OP; SCHUMACHER, JOHANNES; GRAMS, THORSTEN E. E.; BAHNWEG, GÜNTHER; CEULEMANS, REINHART; WERNER, HERBERT; MATYSSEK, RAINER; RENNENBERG, HEINZ; HABERER, KRISTINE
- Abstract
In this study, the effects of different light intensities either in direct sunlight or in the shade crown of adult beech (Fagus sylvatica L.) trees on δ13C and Δ18O were determined under ambient (1 × O3) and twice-ambient (2 × O3) atmospheric ozone concentrations during two consecutive years (2003 and 2004). We analysed the isotopic composition in leaf bulk, leaf cellulose, phloem and xylem material and related the results to (a) meteorological data (air temperature, T and relative humidity, RH), (b) leaf gas exchange measurements (stomatal conductance, gs; transpiration rate, E; and maximum photosynthetic activity, Amax) and (c) the outcome of a steady-state evaporative enrichment model. δ13C was significantly lower in the shade than in the sun crown in all plant materials, whilst Δ18O was increased significantly in the shade than in the sun crown in bulk material and cellulose. Elevated ozone had no effect on δ13C, although Δ18O was influenced by ozone to varied degrees during single months. We observed significant seasonal changes for both parameters, especially in 2004, and also significant differences between the study years. Relating the findings to meteorological data and gas exchange parameters, we conclude that the differences in Δ18O between the sun and the shade crown were predominantly caused by the Péclet effect. This assumption was supported by the modelled Δ18O values for leaf cellulose. It was demonstrated that independent of RH, light-dependent reduction of stomatal conductance (and thus transpiration) and of Amax can drive the pattern of Δ18O increase with the concomitant decrease of δ13C in the shade crown. The effect of doubling ozone levels on time-integrated stomatal conductance and transpiration as indicated by the combined analysis of Δ18O and δ13C was much lower than the influence caused by the light exposure.
- Subjects
EUROPEAN beech; BEECH; FUMIGATION; GAS exchange in plants; FAGACEAE
- Publication
Tree Physiology, 2009, Vol 29, Issue 11, p1349
- ISSN
0829-318X
- Publication type
Article
- DOI
10.1093/treephys/tpp066