US EPA

191275 

Journal Article 

Combining delta C13 and delta O18 analyses to unravel competition, CO2 and O3 effects on the physiological performance of different-aged trees 

Grams, TEE; Kozovits, AR; Haberle, KH; Matyssek, R; Dawson, TE 

2007 

1 

Plant, Cell and Environment
ISSN: 0140-7791
EISSN: 1365-3040 

30 

8 

1023-1034 

17617829 

10.1111/j.1365-3040.2007.01696.x 

WOS:000247819100013 

Combined delta C-13 and delta O-18 analyses of leaf material were used to infer changes in photosynthetic capacity (A(max)) and stomatal conductance (g(l)) in Fagus sylvatica and Picea abies trees growing under natural and controlled conditions. Correlation between g(l) and delta O-18 in leaf cellulose (delta O-18(cel)) allowed us to apply a semi-quantitative model to infer g(l) from delta O-18(cel) and also interpret variation in delta C-13 as reflecting variation in A(max). Extraction of leaf cellulose was necessary, because delta O-18 from leaf organic matter (delta O-18(LOM)) and delta O-18(cel) was not reliably correlated. In juvenile trees, the model predicted elevated carbon dioxide (CO2) to reduce A(max) in both species, whereas ozone (O-3) only affected beech by reducing CO2 uptake via lowered g(l). In adult trees, A(max) declined with decreasing light level as g(l) was unchanged. O-3 did not significantly affect isotopic signatures in leaves of adult trees, reflecting the higher O-3 susceptibility of juvenile trees under controlled conditions. The isotopic analysis compared favourably to the performance of leaf gas exchange, underlining that the semi-quantitative model approach provides a robust way to gather time-integrated information on photosynthetic performance of trees under multi-faced ecological scenarios, in particular when information needed for quantitative modelling is only scarcely available. 

Elevated carbon dioxide (CO2); elevated ozone (O3); Fagus sylvatica; Picea abies; cellulose; photosynthetic capacity (Amax); semi-quantitative model approach; stable isotope ratios; stomatal conductance for water vapour (gl)