Participant 7 CASIROZ meeting Antwerpen 27./28. Nov. 2003

Validation of the ecological significance offormer O3 studies within

Defence capacity and age- related differencesin beech tree responses to O3

Ch. Then and G. Wieser T. Gigele and H. Lohner

Department of Forest Tree Physiology, Federal Office and Research Centrefor Forests, Rennweg 1, A-6020 Innsbruck, Austria

Email: Christiane.Then@uibk.ac.at, Gerhard.Wieser@uibk.ac.at

http://www.forst.tu-muenchen.de/EXT/CASIROZ/

The 2 main objectives are.....

…..to examine if there are consistencies between ozone (O3) induced physiological effects observed in entire adult trees and existing information observed from cuvette experiments with seedlings and findings from branch cuvette O3 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 O3 levels were mounted into selected branches of control trees, and cuvettes receiving ambient air into O3- fumigated trees

2 sets of experiments in 2003:

Methods

Trees respond to O3 induced stress by mechanisms of

avoidance (restriction of O3

uptake by stomatal closure)

defense (detoxification

processes in the leaves)

gas exchange measurements

determination of antioxidants

Participant 7 Participant 8

What we did in 2003 was…..

…..to determine O3 flux into the leaves throughout the growing seasoncuvettes: continuos measurements of microclimate, O3 leaf gas exchange

seedlings: repeated measurements of stomatal conductance (portable gas exchange system LCA3 from ADC)

…..to quantify O3 effects by gas exchange parameters and leaf morphology (SLA)cuvettes: 1) continuos gas exchange measurements (CO2+ H2O) 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 cuvettes2. comparison of sun seedlings with old trees3. 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./17.6.03)

Cuvette experiment

side A: inside cuvettes 1xO3 (outside 2xO3)side B: inside cuvettes 2xO3 (outside 1xO3)

Photosynthesis

0

1

2

3

4

5

6

7

8

side A side B

Pn

in

µm

ol

m-2

s-1

inside cuv.

outside cuv.

Stomatal conductance

0

20

40

60

80

100

120

140

160

side A side B

Gs

in m

mo

l m

-2 s-1

inside cuv.

outside cuv.

Steady state conditions: PAR: 1000 µELeaf temp.: 20°C

Mean values (n = 6)

Inside cuvettes

Outside cuvettes

Cuvette experiment

side A: inside cuvettes 1xO3 (outside 2xO3)side B: inside cuvettes 2xO3 (outside 1xO3)

Single cuvettes (n = 6)

Photosynthesis side B

-2

0

2

4

6

8

10

12

B1 B2 B3 B4 B5 B6

Pn

in

µm

ol

m-2

s-1

inside cuv.

outside cuv.

Photosynthesis side A

-2

0

2

4

6

8

10

12

A1 A2 A3 A4 A5 A6

Pn

in

µm

ol

m-2

s-1

Stomatal conductance side A

0

40

80

120

160

200

240

A1 A2 A3 A4 A5 A6

Gs

in m

mo

l m

-2 s-1

inside cuv.

outside cuv.

Stomatal conductance side B

0

40

80

120

160

200

240

B1 B2 B3 B4 B5 B6

Gs

in m

mo

l m

-2 s-1

inside cuv.

outside cuv.

Cuvettes A1, 2, 3 = Tree 443 A1, 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 417 B1 (upper part), B2 (lower part), B3 (middle part)Cuvette B4 = Tree 413 (middle part)Cuvettes B5, B6 = Tree 410 B5 (lower part), B6 (middle part)

Old trees compared to container seedlings (SUN)Seedlings: older leaves compared to lammas shoots leaves (SUN + SHADE)

Photosynthesis SUN

0

1

2

3

4

5

6

7

8

2xO3 1xO3

Pn

in

µm

ol

m-2

s-1seedlings

seedl. lammas shoots

old trees

Photosynthesis SHADE

0

1

2

3

4

5

6

2xO3 1xO3

Pn

in

µm

ol

m-2

s-1

seedlings

seedl. lammas shoots

Stomatal conductance SHADE

0

25

50

75

100

125

150

2xO3 1xO3

Gs

in m

mo

l m

-2 s-1

seedlings

seedl. lammas shoots

Typical sun crown seedlings with 2 types of leaves

Lammas shoot leaf Older leaf

Stomatal conductance SUN

0

35

70

105

140

175

210

245

280

315

2xO3 1xO3

Gs

in m

mo

l m

-2 s-1

seedlings

seedl. lammas shoots

old trees

First common CASIROZ measuring and sampling on 16th and 17th of JuneCollaboration with participant 2 (sugars, enzyme activities)

participant 8 (antioxidants)

Photosynthesis - SUN seedlings

0

1

2

3

4

5

6

7

8

9

10

10:30 a.m. 12:30 p.m.

Pn

in

µm

ol

m-2

s-1

2xO3

1xO3

Stomatal conductance - SUN

0

20

40

60

80

100

120

140

160

10:30 a.m. 12:30 p.m.

Gs

in m

mo

l m

-2 s-1

2xO3

1xO3

Mean values (n = 10)

Photosynthesis - SHADE seedlings

12:30

-1

0

1

Pn

in

µm

ol

m-2

s-1

2xO3

1xO3

First common CASIROZ measuring and sampling on 16th and 17th of JuneCollaboration with participant 2 (sugars, enzyme activities)

participant 8 (antioxidants)Single values (n = 10)

Photosynthesis - SUN single plants

10:30

0

2

5

7

10

12

2xO3 1xO3

Pn

in

µm

ol

m-2

s-1

Stomatal conductance - SUN single plants

0

50

100

150

200

2xO3 1xO3

Gs

in m

mo

l m

-2 s-1

Photosynthesis - SHADE single plants

10:30

-1

0

1

2

3

2xO3 1xO3

Pn

in

µm

ol

m-2

s-1

1. no differences between the cuvette treatments (inside) 2xO3 and (side B) and 1xO3 (side A)

2. no significant differences between the leaves inside and outside the single cuvettes (2xO3 and 1xO3 ,respectively)

striking: high deviations, particularly inside the cuvettesjust tendentially higher values outside with both O3 treatments which is probably a consequence of the cuvette effect (reduced PAR, aphids) overlaying possible O3 effectsdifferent 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./17.6.03)

no differences between the O3 treatments in the sun

in the shade it seems that occasionally Pn rates are higher with the 1xO3 treatment on the single plant level

comparison of sun seedlings with old treesseedlings (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 (2xO3), too

2. in the sun Pn rates of both leaf types are slightly higher with the 1xO3 treatment, Gs clearly with 2xO3 (lammas shoots), in the shade we find higher Pn + Gs values with 2xO3

3. values of the old trees do not differ with O3 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 2004

1. 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 O3 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