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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: [email protected], [email protected]
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