Transcript then_wieser

Participant 7
CASIROZ meeting Antwerpen 27./28. Nov. 2003
Validation of the ecological significance of
former O3 studies within
Defence capacity and age- related differences
in beech tree responses to O3
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
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
2 sets of experiments in 2003:
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
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 season
cuvettes:
seedlings:
continuos measurements of microclimate, O3 leaf gas exchange
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
seedlings:
repeated gas exchange measurements with LCA3
….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./17.6.03)
Cuvette experiment
Mean values (n = 6)
side A: inside cuvettes 1xO3 (outside 2xO3)
side B: inside cuvettes 2xO3 (outside 1xO3)
Photosynthesis
Pn in µmol m-2 s-1
8
7
inside cuv.
6
outside cuv.
5
4
3
2
1
0
side A
side B
Stomatal conductance
Gs in mmol m-2 s-1
160
Inside cuvettes
140
inside cuv.
120
outside cuv.
100
80
60
40
20
0
side A
Steady state conditions:
PAR: 1000 µE
Leaf temp.: 20°C
side B
Outside cuvettes
Cuvette experiment
Single cuvettes (n = 6)
side A: inside cuvettes 1xO3 (outside 2xO3)
side B: inside cuvettes 2xO3 (outside 1xO3)
Photosynthesis side B
12
10
10
Pn in µmol m-2 s-1
Pn in µmol m-2 s-1
Photosynthesis side A
12
8
6
4
2
8
inside cuv.
6
outside cuv.
4
2
0
0
A1
A2
A3
A4
A5
B1
A6
Stomatal conductance side A
B3
B4
B5
B6
Stomatal conductance side B
240
200
inside cuv.
160
outside cuv.
120
80
40
Gs in mmol m-2 s-1
240
Gs in mmol m-2 s-1
B2
-2
-2
200
inside cuv.
outside cuv.
160
120
80
40
0
0
A1
A2
A3
A4
A5
A6
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)
B1
B2
B3
B4
B5
B6
Photosynthesis SUN
Old trees compared to container
seedlings (SUN)
Seedlings: older leaves compared to
lammas shoots leaves (SUN + SHADE)
8
seedlings
Pn in µmol m-2 s-1
7
seedl. lammas shoots
6
old trees
5
4
3
2
1
0
2xO3
1xO3
Stomatal conductance SUN
315
seedlings
Gs in mmol m-2 s-1
280
seedl. lammas shoots
245
old trees
210
175
140
105
70
35
0
2xO3
1xO3
Photosynthesis SHADE
6
Pn in µmol m-2 s-1
seedlings
5
seedl. lammas shoots
4
3
2
1
Typical sun crown seedlings with 2 types of leaves
0
2xO3
1xO3
Stomatal conductance SHADE
150
Gs in mmol m-2 s-1
seedlings
seedl. lammas shoots
125
100
75
50
25
Lammas shoot leaf
0
2xO3
1xO3
Older 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)
Photosynthesis - SUN seedlings
Photosynthesis SHADE seedlings
12:30
9
2xO3
8
1xO3
1
7
Pn in µmol m-2 s-1
Pn in µmol m-2 s-1
10
6
5
4
3
2
1
0
12:30 p.m .
Stomatal conductance - SUN
160
Gs in mmol m-2 s-1
1xO3
0
-1
10:30 a.m .
2xO3
140
1xO3
120
100
80
60
40
20
0
10:30 a.m .
12:30 p.m .
2xO3
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)
Photosynthesis - SUN single plants
Photosynthesis - SHADE single plants
12
3
10:30
10
Pn in µmol m-2 s-1
Pn in µmol m-2 s-1
10:30
7
5
2
2
1
0
2xO3
0
2xO3
1xO3
Stomatal conductance - SUN single
plants
Gs in mmol m-2 s-1
200
150
100
50
0
2xO3
1xO3
-1
1xO3
Summarizing…..
the steady state measurements inside/outside the cuvettes:
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 cuvettes
just tendentially higher values outside with both O3 treatments which is probably
a consequence of the cuvette effect (reduced PAR, aphids) overlaying possible O3 effects
different trees and heights of the crown are slightly distinguishable
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 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 (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