Participant 7CASIROZ meeting Antwerpen 27./28. Nov Validation of the ecological significance of former O 3 studies within Defence capacity and age- related differences in beech tree responses to O 3 Ch. Then and G. Wieser T. Gigele and H. Lohner Department of Forest Tree Physiology, Federal Office and Research Centre for Forests, Rennweg 1, A-6020 Innsbruck, Austria

The 2 main objectives are..... …..to examine if there are consistencies between ozone (O 3 ) induced physiological effects observed in entire adult trees and existing information observed from cuvette experiments with seedlings and findings from branch cuvette O 3 fumigations …..to clarify if twigs posses besides their carbon autonomy also an autonomy in their defense metabolism or if they profit from the defense capacity of neighbouring crown parts

Containers with seedlings were positioned within fumigated and non fumigated areas in the shade and the sun crown, respectively Climate- controlled cuvettes receiving enhanced O 3 levels were mounted into selected branches of control trees, and cuvettes receiving ambient air into O 3 - fumigated trees 2 sets of experiments in 2003:

Methods Trees respond to O 3 induced stress by mechanisms of avoidance (restriction of O 3 uptake by stomatal closure) defense (detoxification processes in the leaves) gas exchange measurements determination of antioxidants Participant 7Participant 8

What we did in 2003 was….. …..to determine O 3 flux into the leaves throughout the growing season cuvettes: continuos measurements of microclimate, O 3 leaf gas exchange seedlings:repeated measurements of stomatal conductance (portable gas exchange system LCA3 from ADC) …..to quantify O 3 effects by gas exchange parameters and leaf morphology (SLA) cuvettes:1) continuos gas exchange measurements (CO 2 + H 2 O) by a fully automatic gas exchange system 2) repeated leaf gas exchange measurements of cuvette comparable twigs of the same tree nearby the cuvettes 3) Steady state measurements of leaves inside and outside the cuvettes at the end of the fumigation period repeated gas exchange measurements with LCA3 seedlings:

….and in cooperation with groups 2, 8, 6 …..to determine defense capacity (antioxidants), sugars, starch and enzyme activities cuvettes:leaves of trees inside/outside the cuvettes were harvested at the end of the fumigation period in September just after gas exchange measurements on the same leaves seedlings:leaves of container seedlings were harvested during the 3 CASIROZ sampling weeks just after gas exchange measurements on the same leaves in September participant 8 received leaves of 4 containers (one per treatment sun + shade) for determination of antioxidants …..to characterize mycorrhizal colonization seedlings:in September participant 6 received roots + soil of 4 containers (one per treatment sun + shade) for determination of myorrhizae

Data processing is under way….. However, here some first results: Steady state measurements at the end of the fumigation period in September 1.comparison of leaves inside and outside the cuvettes 2.comparison of sun seedlings with old trees 3.Seedlings (sun + shade): comparison of 2 types of leaves (old leaves and lammas shoots leaves) ambient measurements of seedlings (sun + shade) during the first CASIROZ sampling in June (16./ )

Cuvette experiment side A: inside cuvettes 1xO 3 (outside 2xO 3 ) side B: inside cuvettes 2xO 3 (outside 1xO 3 ) Steady state conditions: PAR: 1000 µE Leaf temp.: 20°C Mean values (n = 6) Inside cuvettes Outside cuvettes

Cuvette experiment side A: inside cuvettes 1xO 3 (outside 2xO 3 ) side B: inside cuvettes 2xO 3 (outside 1xO 3 ) Single cuvettes (n = 6) Cuvettes A1, 2, 3 = Tree 443A1, A3 (lower part of sun crown rods), A2 (middle part) Cuvette A4 = Tree 439 (middle part) Cuvettes A5, A6 = Tree 482 (middle part) Cuvettes B1, B2, B3 = Tree 417B1 (upper part), B2 (lower part), B3 (middle part) Cuvette B4 = Tree 413 (middle part) Cuvettes B5, B6 = Tree 410B5 (lower part), B6 (middle part)

Old trees compared to container seedlings (SUN) Seedlings: older leaves compared to lammas shoots leaves (SUN + SHADE) Typical sun crown seedlings with 2 types of leaves Lammas shoot leafOlder leaf

First common CASIROZ measuring and sampling on 16th and 17th of June Collaboration with participant 2 (sugars, enzyme activities) participant 8 (antioxidants) Mean values (n = 10)

First common CASIROZ measuring and sampling on 16th and 17th of June Collaboration with participant 2 (sugars, enzyme activities) participant 8 (antioxidants) Single values (n = 10)

1. no differences between the cuvette treatments (inside) 2xO 3 and (side B) and 1xO 3 (side A) 2. no significant differences between the leaves inside and outside the single cuvettes (2xO 3 and 1xO 3, respectively) striking: high deviations, particularly inside the cuvettes just tendentially higher values outside with both O 3 treatments which is probably a consequence of the cuvette effect (reduced PAR, aphids) overlaying possible O 3 effects different trees and heights of the crown are slightly distinguishable Summarizing….. the steady state measurements inside/outside the cuvettes: the ambient measurements of seedlings (sun + shade) during the first CASIROZ sampling in June (16./ ) no differences between the O 3 treatments in the sun in the shade it seems that occasionally Pn rates are higher with the 1xO 3 treatment on the single plant level

comparison of sun seedlings with old trees seedlings (sun + shade): comparison of 2 types of leaves (old leaves and lammas shoots leaves) 1.the seedlings lammas shoots leaves show significantly higher Pn and Gs rates than old leaves in both sun treatments and tendentially in the shade (2xO 3 ), too 2.in the sun Pn rates of both leaf types are slightly higher with the 1xO 3 treatment, Gs clearly with 2xO 3 (lammas shoots), in the shade we find higher Pn + Gs values with 2xO 3 3.values of the old trees do not differ with O 3 treatments 4.Pn rates: lammas shoots leaves > tree leaves > old leaves Gs: old trees have low values because of drought, but the old leaves of the seedlings are only slightly higher although they were well watered The role of the lammas shoots has to be clarified !

Planned changes for the growing season we will install a humidity control system in the cuvette experiment to avoid problems with condensation in the cuvettes at times of high air humidity as well as light and humidity sensors inside the cuvettes 2. we will also install control cuvettes next to the cuvettes of a particular O 3 regime advantage: we will avoid the cuvette effect (f.ex. light, aphids) in the comparison inside/outside disadvantage: reduction of the sample number, risk of breaking twigs 3. all cuvettes will be installed at the same height 4. all trees should have the same cuvette number

Special thanks to our artist Hans Lohner for the technical drawings