Skógræktarritið - 15.05.2001, Side 87

Russian larch originating from
the Archangel district, which is
better adapted to Icelandic con-
ditions, has been used almost
exclusively during the last 20
years.
Larch was first planted in
lceland around 1900 and the first
true Russian larch stands were
planted in the late 1930's. Their
mean annual increment at age 60
is 7 mVha/yr and the maximum
height is 21 m.
Larch survives and grows best
on rather poor heathland and
eroded sites, making it ideal for
reclaming degraded grazing land.
Its mycorrhizal associate, the
larch bolete (Suíllus grevillie), fol-
lows it wherever it is planted and
is in fact essential for survival
and growth. Because larch lets a
large amount of light through to
the ground, rich understory vege-
tation usually developes under a
larch canopy, even when larch is
used to reclaim gravel mines.
Russian larch achieves good
form and is usable for timber
production only in interior val-
leys in N- and E-lceland. How-
ever, it is an excellent nurse
species for spruces and even
lodgepole pine and planting of
such mixtures is increasing.
Several fungal pests have
attacked Siberian larch and
Russian larch in lceland, with
larch canker (Lachnellula wilkomii)
and/or conifer canker (Phacidium
coniferarum) limiting its usefull-
ness in the more maritime
regions of S- and W- Iceland.
Selection and breeding for im-
proved adaptation is under way
and production of putatively
improved seed in a greenhouse
seed orchard has commenced.
Russian larch, mostly originat-
ing from Finnish seed orchards,
has been the most planted tree
species in lceland during the last
decade, and from 1945-1998, 16
million seedlings of Russian and
Siberian larch were planted.
Natural regeneration has been
notet in many places.
Sitka spruce (Picea sitchensis
(Bong.) Carr.)
Sitka spruce was first planted in
Iceland in 1937, with the first
large seed lots arriving from
Alaska in 1941. It was extensively
planted during the 1950's and
early 60’s but interest in it dimin-
ished after much of it was severe-
ly damaged in 1963. Planting has
increased again since 1990 and it
is now the second most planted
exotic species, comprising 19% of
trees planted in 1999. About 10
million Sitka spruce were planted
in Iceland from 1945 to 1998,
putting it in 4lh place among
species planted.
After a long establishment
phase, sometimes taking 20-30
years to reach breast height,
Sitka spruce outgrows all other
conifers. Mean annual increment
at age 35-48 is 5-9 mVha/yr with
current annual inncrement 16-26
mVha/yr and dominant height 8-
14 m. The tallest Sitka spruce in
Iceland is 20 m at age 45. Sitka
spruce will be the main timber
producing species in Iceland. It is
also the most wind resistant
spruce species and can be grown
on sites degraded by grazing.
The only serious pest that
attacks Sitka spruce in iceland is
the green spruce aphid (Elatobium
abietinum), with severe defoliation
often occurring after mild win-
ters. Sitka spruce is rarely killed
by the aphid, but growth is
diminished for some years after
severe defoliation.
Natural regeneration has been
noted in several places.
White spruce (Picea glauca
(Moench) Voss)
White spruce was planted in two
places in Iceland around 1900.
The origin of the trees was east-
ern North America and they
faired poorly although a few indi-
viduals still survive. Several
stands of white spruce were
planted in the 1950’s, the materi-
al mostly originating from the
Kenai Peninsula in Alaska, but
no white spruce was planted
from 1970 to the early 90's.
White spruce could be called
the "forgotten spruce". However,
stands from the 50's are now
growing well and interest in the
species is increasing. It has very
good form and branching habit
and should therefore be of inter-
est as a timber species. At age 34
on a good site, the mean annual
increment is 3.8 mVha/yr and
dominant height is close to 10 m.
Lutz spruce (Picea x lutzii Little)
This is the hybrid between Sitka
spruce and white spruce that
grows naturally in southern
Alaska. It was first planted in
Iceland in 1958 in a trial of four
spruce species. The dominant
height is 12 m at age 40. Lutz
spruce is intermediate in most
respects between its parent
species, having higher growth
rate than white spruce and better
form and finer branches than
Sitka spruce.
Norway spruce (Piccs abies (L.)
Karst.)
Norway spruce was first planted
in lceland shortly after 1900 and
the tallest of these trees are now
17m. Planting of Norway spruce
stands commenced in 1948 and
by the late 50's, it was one of the
most planted species. Substan-
tial planting continued into the
mid 1970's, after which it de-
creased, the reason being very
poor growth on site types gener-
ally available for afforestation
(heathland) and poor wind toler-
ance. Norway spruce now com-
prises only about 1% of trees
planted in Iceland annually.
SKÓGRÆKTARRITIÐ 2001 l.tbl.
85