Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: delayed effect of ozone fumigation on photosynthesis of Norway spruce...
Nội dung Text: Báo cáo lâm nghiệp: "delayed effect of ozone fumigation on photosynthesis of Norway spruce"
A delayed effect of ozone fumigation
on photosynthesis of Norway spruce
D. Eamus J.D. Barnes L. Mortensen
2
1 3 H. Ro-Poulsen
4
A.W. Davis n
2
2avison
1Institute of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian EM?6 OOB, U.K.,
Department
2 of Biology, Ridley Building, The University, Newcastle upon Tyne, U.K.,
National
3 Agency of Environmental Research, Institute of Air Pollution, Frederiksborgvej 399,
D-4000, Roskilde, Denmark, and
1nstitute
4 of Plant Ecology, University of Copenhagen, 0 Farimagsyade, 2D Dli353. Copenhagen,
Denmark
peratures and light intensity are sufficiently
Introduction
high. Frost and winter dessication are
therefore temporally separated from the
Much of the research investigating the
periods of high ozone concentrations.
effects of gaseous pollutants upon plants
Consequently, if ozone is to influence
has been concerned with dose-response
plant sensitivity to frost, it must exert a
relationships, particularly during the period long-lasting effect. This paper briefly
of fumigation or in between the periods of
reports the results of an investigation into
fumigation, in the summer. However, there the long-lastinc effects of ozone fumiga-
l
is increasing evidence that these pollu- tion upon photosynthesis of Norway
tants increase plant susceptibility to winter
spruce. Measurements were conducted in
injury (Barnes and Davison, 1988; Brown the field 6-7 mo after the cessation of 2 yr
ef al., 1987). This is especially problematic summer fumigation with ozone.
for conifers, since they maintain needles
and some metabolic activity throughout
the winter. Indeed, there is increasing evi-
dence that the forest decline documented
Materials and Methods
for northeastern U.S.A. and Europe
results from the interaction of various
abiotic and biotic factors including air pol- Four yr old trees of Norway
seedl-propagated
lutants, frost and winter dessication spruce (Picea alries (L.) Karst) were exposed,
(Brown et aL, 1987; Barnes and Davison, in duplicate open top chambers at Riso National
Laboratory, 30 krn west of Copenhagen, Den-
1988).
mark, to either charcoal-filtered air or ambient
Anthropogenic ozone production primar- air plus 50 ppb ozone, from July to October
the when tem-
ily during 1986 and May to October, 1987.
occurs summer
On November 25th, 1987 (42 d after the ces-
sation of ozone fumigation), branches bearing 3
needle yr age classes were used for fluores-
cence analysis. A portable fluorometer (Richard
Branker Research) attached to an oscilloscope
with output to a digital plotter was used (Barnes
and Davison, 1988). F was readily determined
o
due to the storage and display capabilities of
the Gould 1425 digital storage oscilloscope,
allowing millisecond resolution of the fluores-
cence curves. Fluorescence of wavelength
> 710 nm (PS[I fluorescence) was measured.
The Branker instrument provides illumination of
approximately 4 ¡ae F (non-variable
.
1
s
2
m-
’o
fluorescence), F (variable fluorescence) and F
v r
(rate of rise of variable fluorescence) were
determined as described elsewhere (Barnes
and Davison, 1988). On May 8th, 1988 (207 d
after the cessation of fumigation), rates of pho-
tosynthesis and transpiration were measured in
the field using a portable ADC infrared gas ana-
lyzer and Parkinson leaf chamber. Current and
previous yr needles were used. Twelve repli-
cate branches per treatment were measured.
Further details are given elsewhere (Eamus et
al., 1989)
Results
ozone-filtered trees. Similarly, ozone fumi-
TableI shows that for both current and gated trees fixed 29% (current) and 50%
previous yr needles, the mean rate of (previous) more C0 per hour than char-
2
assimilation over the day was significantly coal-filtered trees. From Figs. 1 and 2, it
(P
Table II shows that there
and previous yr needles (Fig. 1), and 2) signifi-
was no
both a greater light saturated rate of assi- cant effect of the treatments upon F for
,
o
any of the 3 yr classes of needles. How-
milation and a higher apparent quantum
yield than the charcoal-filtered trees (Fig. ever, the yield of variable fluorescence
2). The r! values for the apparent quantum (F was significantly reduced in all yr
)
v
yield regressions of the light response classes, by ozone fumigation. The rate of
rise of variable fluorescence (F was
data (Fig. 2) and the temperature respon- )
r
significantly decreased in current yr
se of assimilation (Fig. 1) varied between
0.8 and 0.97, indicating a satisfactory fit of needles only. There was no effect on C+11
or C+2 yr needles.
the lines to the data sets.
and previous yr needles (Table I). This
Discussion and Conclusion
result is in contradiction with the data of
large numbers of papers reporting that
ozone fumigation causes decreased rates
fumigation resulted in significantly
Ozone
of assimilation (A). However, examples of
mean daily rates of assimilation
enhanced
ozone fumigation not affecting rates of A
in comparison to control plants, for current
tosynthetic processes (principally electron
(Chappelka and Chevone, 1988; Taylor et
transport) which was not expressed as
al., 1986) have been reported. The majori-
visible symptoms. Such latent damage
ty of these papers have been concerned
with measurements of A has been associated with increased frost
during the sum-
coincidental with the time of sensitivity (Barnes and Davison, 1988).
period
mer
ozone fumigation. The data presented in These changes in fluorescence parame-
ters were observed 42 d after cessation of
this paper show that ozone increased A in
the spring prior to budburst following a ozone fumigation, indicating that these
summer of ozone fumigation. Ozone trees were more sensitive to early frost
events as well as late frost events.
decreases frost hardiness of Norway and
Sitka spruce (Barnes and Davison, 1988;
Lucas et al., 1988) particularly at the start
and end of the winter period (i.e., during
hardening and dehardening). It is suggest- References
ed from the data of this study, that trees
exposed to ozone during the summer Barnes J.D. & Davison A.W. (1988) The influ-
were less hardy in May the following yr
ence of ozone on the winter hardiness of Nor-
and thus were more active than control way spruce. Neuv Phytol. 108, 159-166
plants. From this it may be predicted that Brown K.A., Roberts T.M. & Blank L.W. (1987)
ozone-fumigated trees would have a Interaction between ozone and cold sensitivity
and light response
higher temperature in Norway spruce: a factor contributing to the
forest decline in central Europe. New Phytol.
for A than control plants which were
curve
105, 149-155
hardier and less metabolically active. This
Chappelka A.H., Chevone B.I. & Seiler J.R.
indeed was observed. Quantum efficiency,
(1988) Growth and physiological responses of
the rate of light-saturated A and the tem-
yellow poplar seedlings exposed to ozone and
perature response of A was greater in simulated acidic rain. Environ. Pollut. 49, 1-18
8
ozone-fumigated plants than controls Eamus D. & Fowler D. (1989) Photosynthetic
(Figs. 1 and 2, Table I). It is concluded that and stomatal conductance responses of red
ozone fumigation exerts a long-term effect spruce seedlings to acid mist. Plant Cell Envi-
ron. in press
upon Norway spruce via its influence upon
the processes of hardening and sub- Eamus D., Barnes J.D., Mortensen L., Ro-Poul-
sen H. & Davison A.W. (1989) Persistent effects
sequent dehardening. This makes the
of summer ozone fumigation on C0 assimila-
2
trees more frost sensitive, but also allows
tion and stom;atal conductance in Norway
the ozone fumigated trees to take better
spruce. Environ. Pollut in press
advantage of warm, sunny days early in Lucas P.W., Cottam D.A., Sheppard L.J. &
the season. Francis B.J. (1988) Growth responses and
delayed winter hardening in Sitka spruce follow-
Table II shows that ozone fumigation
ing summer exposure to ozone. New Phytol.
significantly reduced the yield of variable 108, 495-504
fluorescence (F for all yr classes, and
)
v
Taylor G.E., Norby R.J., McLaughlin S.B., John-
also the rate of rise (F of induced fluores-
)
r son A.H. & Turner R.S. (1986) Carbon dioxide
cence in the current yr needles. Such
assimilation and growth of red spruce seedlings
declines indicate that previous exposure to in response to ozone and precipitation chemis-
0 caused long-term damage to the pho- try and soil type. Oecologia (Berlin) 70, 163-171
3
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