English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

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 δ 13 C and Δ 18 O were determined under ambient (1 × O 3 ) and twice-ambient (2 × O 3 ) 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,  g  s ; transpiration rate,  E ; and maximum photosynthetic activity,  A  max ) and (c) the outcome of a steady-state evaporative enrichment model. δ 13 C was significantly lower in the shade than in the sun crown in all plant materials, whilst Δ 18 O was increased significantly in the shade than in the sun crown in bulk material and cellulose. Elevated ozone had no effect on δ 13 C, although Δ 18 O 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 Δ 18 O between the sun and the shade crown were predominantly caused by the Péclet effect. This assumption was supported by the modelled Δ 18 O values for leaf cellulose. It was demonstrated that independent of RH, light-dependent reduction of stomatal conductance (and thus transpiration) and of  A  max  can drive the pattern of Δ 18 O increase with the concomitant decrease of δ 13 C in the shade crown. The effect of doubling ozone levels on time-integrated stomatal conductance and transpiration as indicated by the combined analysis of Δ 18 O and δ 13 C was much lower than the influence caused by the light exposure.

tree physiology

Within-canopy and ozone fumigation effects on δ 13 C and Δ 18 O in adult beech ( Fagus sylvatica ) trees: relation to meteorological and gas exchange parameters