1. On the quest for ozone correlations Gas exchange data Markus Löw, K.-H. Häberle and R. Matyssek loew@wzw.tum.de Ecophysiology of Plants, Freising, Germany Technische Universität München

2. Method gas exchange data is plotted against ozone indices AOT40 and cumulative ozone uptake (Flux) the data must be compared to 1xO3 to get rid of annual effects formula: value from 1xO3 minus value from 2xO3 expressed as difference to 1xO3 in [%] 1xO3 = 0% linear fit of the normalized difference Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax 0

3. Amax 360 2003 & 2004 sun Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

4. Normalized difference Amax 360 October 2003 ( ) Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

5. Normalized difference Amax 360 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

6. Normalized difference Amax 360 October 2004 ( ) May 2004 ( ) Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

7. Normalized difference Amax 360 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

8. Normalized difference Amax 360 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

9. Comparison 2003 - 2004 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

10. Vcmax 2004 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax Vcmax = maximum RuBP saturated rate of carboxylation [µmol m -2 s -1 ] (Farquhar 1980)

11. Vcmax 2004 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

12. Vcmax 2004 Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

13. stomatal conductance gH 2 O Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

14. stomatal conductance gH 2 O Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

15. stomatal conductance gH 2 O Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

16. Water Use Efficiency [µmol CO 2 m -2 s -1 / mmol H 2 O m -2 s -1 ] (after Larcher 2001) Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

17. Normalized difference WUE ( ) Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax

18. Conclusions „normalized difference“ is a useful approach there is a linear relationship between rate of photosynthesis and ozone during summer months June – September 2003 and 2004 comparison of the year 2003 and 2004 shows drought effect throughout the growing season there is a good correlation of gH 2 O to ozone WUE is not different in 2003 and 2004 WUE is more correlated to AOT40 than COU or date based an gas exchange data we can neither prefer AOT40 nor COU Method Gas Exchange Amax WUE Normalized difference Conclusions Stomatal conductance Vcmax