Nội dung Text: Báo cáo lâm nghiệp: "fumigation of Norway spruce at timberline"
fumigation of Norway spruce at timberline
Ozone
M. Bodner
2
W.M. Havranek G. Wieser
1 1
1 Forstliche Bundesversuchsanstalt, Aul3enstelle fOr subalpine Waldforschung, Innsbruck, and
2 fur Botanik der Universitit Innsbruck, Austria
Institut
trations and to examine the effects of 0
Introduction 3
on gas exchange and chlorophyll fluores-
cence, both known to be indicators of
Ozone is thought to be involved in forest
latent or hidden 0 injury.
3
decline (Bucher, 1986; Krause et al.,
1986), especially at high altitudes, where
increased 0 levels together with a fast
3
increase in forest damage has been
Materials and Methods
observed (Berichte Tiroler Landtag,
1985-1988). Many investigations on the
impact of 0 on trees have been carried
3 For this study, a 60 yr old spruce tree (Picea
abies (L.) Karst.) near the Klimahaus research
out under laboratory conditions, mainly
station on Mt. Patscherkofel (1920 m a.s.l.)
with seedlings, but few in the field (Smidt,
near Innsbruck was selected. For each treat-
1978; Pye, 1988). Experimental data of ment, 6 similar twigs were enclosed in plexi-
effects of 0 on adult trees under field
3 glass chambers, where the air was exchanged
conditions are rare (Coyne and Bingham, 3-4 times per minute. 0 treatments were as
3
follows: control (charcoal-filtered air), ambient
1982) or lacking altogether as for instance
air, ambient air + 38 ppb 0 (1987) and 120 ppb
3
for the timberline region. Therefore it
0 (1986), respectively. The twigs were left in
3
seemed to be of interest to fumigate an the fumigation chambers for one full growing
adult spruce tree with various 0 concen-
3 season (July to September). Monthly means of
0 air temperature, relative humidity and sums Stomatal conductance
,
3
of precipitation for 1986 and 1987 are given in
Table I.
In no case investigated did 0 treatments
3
0 was produced with a UV-lamp (Osram
3
reduce stomatal conductance to values
HNS-UOZ) and 0 concentrations in the cham-
3
bers were checked daily with an ozone meter lower than those of control twigs. On the
(Monitor Labs Mod. 8810). All gas exchange
contrary, low doses of 0 seemed to
3
made in ambient air with
measurements were a
increase conductance at least temporarily.
thermoelectrically controlled Minicuvette Sys-
In 1986, a 4 wk fumigation with 120 ppb
tem (Walz, Effeltrich, FRG). Measurements
were taken at light saturation, leaf temperatures led to a statistically significant increase of
of 21°C (1986) or 18°C (1987) and at a relative conductance of 45% compared to 0 -free
3
vapor pressure deficit of 10.6 Pa/kPa.
controls, which disappeared after 12 wk of
Chlorophyll fluorescence of small twigs from fumigation (Table II). Under the 1987
all cuvettes (i.e., 6 replicates per treatment) was
conditions, all treatments resulted in simi-
also measured in situ after predarkening with
lar stomatal conductance. A stomatal
light tight bags in 1987 (23 September, during
daylight hours). A pulse-modulation fluorometer behavior similar to that observed in 1986
(Pam 103, Walz, Effeltrich, FRG) was used, as was found by !Celler and H5sler (1984) in
describedby Schreiber et aL (1986).
spruce seedlings, where conductance was
also higher and stomata reacted more
sluggishly than in controls.
Results and Discussion
fluorescence and net
Chlorophyll photo-
synthesis
At the end of the fumigation period, all
twigs looked healthy and there was no
After 8 wk of fumigation in 1987, all
visible needle damage. However, 0 3
samples exhibited normal fluorescence
concentrations were high enough to alter
transients. There were no significant differ-
gas exchange parameters.
between the quenching coefficients 12 wk of fumigation with
-treated
3
0 twigs.
ences
ambient air also did not alter photosynthe-
g.
Fi
( 1The quotient (F F - )/
max O ’
max
which is a quantitative measure of the sis significantly compared to controls (Fig.
photochemical efficiency of photosystem 2). Elevated 0 levels, however, led to a
3
II, was between 0.81 and 0.82 for all 3 significant decline in photosynthesis. Cur-
treatments which is within the normal rent year’s needles fumigated with
range for and Dem- ambient air + 38 ppb 0 during daylight
C plants (Bj6rkman
3 3
hours showed a decline of 10% and
mig, 1987).
needles treated with 120 ppb 0 contin-
3
At the time, uously showed a decrease of 30% when
photosynthesis
net
same
but not significantly reduced in compared to controls. Last year’s needles
slightly
was
had reduced photosynthesis by about 5% Thus conclude that 0 concentrations
3
we
after treatment with ambient air + 38 ppb higher than 100 ppb persisting for long
03- time periods or a general further increase
of 0 above present ambient levels would
3
In discussing our results, we always reduce photosynthesis in spruce, which, in
have to keep in mind that this fumigation combination with bad climatic or poor soil
experiment was performed with only one conditions, might result in a greater sus-
tree. These results indicate that at timber-
ceptibility to climatic and biotic damage.
line, where pollutants other than 0 were
3
largely absent (Smidt, 1983), ozone
concentrations of the ambient air did not
alter gas exchange or chlorophyll fluores-
References
cence significantly within one vegetation
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could stimulate stomatal opening leading Zustand der Tiroler WAider. Amt der Tiroler Lan-
to higher ozone uptake into the needles desregierung, Landesforstinspektion Innsbruck
and reducing their photosynthetic rates in
Bj6rkman O. & Demmig B. (1987) Photon yield
spite of the higher stomatal conductance. of0 and chlorophyll fluorescence characteris-
2
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von ozon
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