Skógræktarritið - 15.05.2001, Page 171

establishment was a problem for
the species at the wind blown
site, although it survived well in
the lower competition pressure
after transplantation.
Lowered competition was
probably the reason why Trientalis
europaea, as well, showed a good
survival in the lichen heath after
transplantation from the blue-
berry community in spite it was
not naturally growing at the wind
swept site. It also showed a sur-
prisingly high flowering percent-
age at the lichen heath which
may have been caused by a lower
competition for nutrients after
reduction in the amount of V.
myrtillus and D. flexuosa by trans-
plantation.
A third species of vascular
plants obviously favoured by
lower competition after trans-
plantation was Carex bigelowii.
There was a clear increment both
in biomass and relative cover of
this species after transplantation
both from the blueberry commu-
nity to the lichen heath and vica
versa. Also the flowering percent-
age of the species was highest in
the transplanted plots.
Among the cryptograms the
lichen Cetraria nivalis, normally
growing at wind swept dry ridges,
seemed to have very strong
requirements just for such condi-
tions. By transplantation to the
moister blueberry heath ( some-
times ice covered in winter) it
showed a decrease in clorophyll
and a yellowing of the thalli
already one year after they were
moved, may be due to lack of
oxygen. In winter relative cover of
the species at the blueberry com-
munity 4 years after transplanta-
tion was 3.4 % of the cover in the
selftransplanted plots at the
lichen heath, reduced to 0.75%
after 9 years as seen in Table 1,
and the biomass was reduced to
approximately zero. In the plots
transplanted from the blueberry
to the lichen heath on the other
hand considerable amounts of C.
nivalis had blown into the plots
after 9 years, approximately 1/3
of the amount at the selftrans-
planted plots (Table 1) in the
blueberry community.
Also most of the Cladonia
species (and particularly the
reindeer lichens) showed re-
duced amounts after transplanta-
tion from the lichen heath to the
blueberry community, while
pieces of the thalli even of these
species blowed into the plots by
the reciprocal transplantation.
Denser and lower species of
lichens, for instance Ochrolecfiia
frigida, Cladonia coccifera (and simi-
lar species), as well as the
species Cetraria islandica, showed
a wider tolerance to the environ-
ment and were relatively stable
elements of the plots in both
communities.
Bryophytes are generally more
common in the moister blueber-
ry community than at the wind
swept ridges. In the plots trans-
planted to the blueberry heath
Dicranum increased in cover after
9 years (Table 1), but the plants
were still small. Polytrichum had
also started some establisment
after the transplantation to the
moister environment, but less
than expected. By the reciprocal
transplantation to the lichen
heath there was a limited reduc-
tion in mosses after 9 years.
Liverworts in the study (data
not given in Table 1) strongly
showed their need for moist con-
dition by a reduction to nearly
zero, particularly in the biomass,
by transplantation from the blue-
berry to the lichen heath. By the
drier surface conditions because
of reduced plant cover after
transplantation from the lichen
heath to the blueberry communi-
ty only small amounts of liver-
worts were found even after
transplantation in that direction.
Generally the results mean that
the hypothesis of quicker reestab-
lisment of vegetation at the blue-
berry community than at the
lichen heath did not seem to be
true. Reinvation of woody plants
as V. myrtillus and Empetrum herma-
phoditum may not take place in low
alpine or subalpine areas through
10-20 years, showing the slow
recovery in mountains.
The transplantation studies at
Hardangervidda show impacts of
importance by eventual changes
in the climate in polar-alpine and
subpolar- subalpine regions
(Callaghan etal., 1995; Crawford,
1997; Grabherr etal., 1994;Guisan
et ai, 1995; Hollister, 1999). A
main conclusion is that general-
izations about responses in plant
communities on environmental
changes as a whole must be
drawn by care. A response seems
very much to be dependent on
the various species and their
growth requirements. Competi-
tion seems to be extremely
important for the presence and
vitality of some species. Impor-
tant changes in the species com-
position may also take place
because of a combination of
effects by changes in competition
and in environmental factors.
Changes in the climate causing
less snow cover, colder winters
and drier condititions may cause
effects of the type found by
transplantations from the blue-
berry community to the lichen
heath. Species normally bound
to the blueberry heath, for
instance V. myrtillus, will strongly
decrease or disappear, when
moved to a wind blown site.
Similarly, a reduction in D. flexu-
osa and mosses may be observed,
while V. vitis-idaea and reindeer
lichens (included C. nivalis) may
increase, the lichens mainly
because of wind blowing pieces
into the plot, when transplanted
from a more snow covered site.
SKÓGRÆKTARRITIÐ 2001 I. tbl
169