Y. Scheidegger et al., Linking stable oxygen and carbon isotopes with stomatal conductance and photosynthetic capacity: a conceptual model, OECOLOGIA, 125(3), 2000, pp. 350-357
Based on measurements of delta O-18 and delta C-13 in organic matter of C-3
-plants, we have developed a conceptual model that gives insight into the r
elationship between stomatal conductance (g(1)) and photosynthetic capacity
(A(max)) resulting from differing environmental constraints and plant-inte
rnal factors. This is a semi-quantitative approach to describing the long-t
erm effects of environmental factors on CO2 and H2O gas exchange, whereby w
e estimate the intercellular CO2 concentration (c(i)) from delta C-13 and t
he air humidity from delta O-18. Assuming that air humidity is an important
factor influencing g(1), the model allows us to distinguish whether differ
ences in c(i) are caused by a response of g(1) or of A(max). As an applicat
ion of the model we evaluated the isotope data from three species in plots
differing in intensity of land use (hay meadows and abandoned areas) at thr
ee sites along a south north transect in the Eastern Alps. We found three d
ifferent delta O-18-delta C-13 response patterns in native and planted gras
sland species (cultivated in the greenhouse). After preliminary confirmatio
n by gas-exchange measurements we conclude that the proposed model is a pro
mising tool for deriving carbon water relations in different functional gro
ups from delta O-18 and delta C-13 isotope data.