Abstract
Diurnal measurements of photosynthetic pr
ocesses, effective quantum yield of
photosystem II (
F
PSII
), photosynthetic electron transport rate (ETR) were done in three domi−
nant species of Arctic tundra (
Silene acaulis
,
Dryas octopetala
,
Salix polaris
) in Petunia−
bukta, Spitsbergen. Daily courses of net photosynthesis (P
N
) were calculated from chloro−
phyll fluorescence data and daily photosynthesi
s evaluated. The short−term field measure−
ments were carried out in summer 2009,
and 2010. Fluorometric parameters (
F
PSII
and ETR)
were measured each 5 minutes as well as microc
limate characteristics of the site for 10 (2009)
and 8 days (2010), respectively. In all species
photosynthetic ETR was well related to incident
photosynthetically active radiation a
nd leaf temperature. In general,
D. octopetala
exhibited
slightly lower ETR than the other two speci
es. Estimated maximu
m photosynthetic rate
(P
Nmax
) reached 17.6, 21.4, and 22.9 μmol CO
2
m
−2
s
−1
for
S. polaris
,
S. acaulis
,and
D. octopetala
, respectively. Daily photosynthesis reach
ed comparable values in all species,
D. otopetala
, however, exhibited slightly lower values than the other two species both for
overcast and fully sunny days (3.9 and 13.4 mmol CO
2
m
−2
d
−1
, respectively). The range of
daily photosynthesis for
S. polaris
and
S. acaulis
studied, reached the ranges of 4.6–6.9 and
14.6–15.2 mmol CO
2
m
−2
d
−1
for overcast and fully sunny day, respectively.
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