Skógræktarritið - 15.05.2001, Blaðsíða 108

through the Millennium Com-
mission. The project has been
managed by Highland Birch-
woods and was steered by the
Montane Scrub Action Group
(MSAG), a partnership of individ-
uals, supported by their organi-
sations, with interest and exper-
tise in land use, conservation
and upland research. As a first
attempt to draw broad attention
to these neglected habitats and
to stimulate interest in their
restoration, the project aimed to
raise awareness through better
understanding of the issues
associated with their current dis-
tribution and the potential recov-
ery of the communities.
What is montane scrub?
The term scrub encompasses
tree and shrub growth (excluding
ericoid and prostrate dwarf
shrubs such as Arctostaphylos spp.,
Salix repens L. and S. herbacea L ),
less than five metres in height
(Hester, 1984). Tansley (1939)
split scrub into three main types,
seral (or successional), sub-seral
(in arrested succession) and cli-
max. The interest of the project
has been Scottish climax scrub
found in situations where the cli-
mate restricts the upward growth
of trees, specifically at high alti-
tude but including the western
'oceanic' seaboard where the
montane scrub zone approaches
sea level (figure 1).
in the absence of a Scottish
equivalent to 'krummholz’, the
MSAG defined montane scrub as
'tfie stunted, crooked and twisted little
trees in tfie zone of the treeline and tfie
tall shrubs wfiicfi naturally or poten-
tially grow at the treeline and in tfie
subalpine and low alpine' (Mardon,
1997). Not only are we concerned
with the tall shrubs of this zone
but also the high altitude
extremes of upland woodland
types (table 1). Montane scrub is
a transition between the forest
and montane heaths or grass-
lands, where the tall shrubs form
mosaics with both groups of
stunted trees and with the
heaths and grasslands.
The main phytosociological
classification system in Britain,
today, is the National Vegetation
Classification (NVC) (Rodwell
1991) which describes vegetation
types on the basis of the fre-
quency (over 5%) and abundance
of plant species found across the
samples gathered for that pur-
pose. Great emphasis is placed .
on the homogeneity of the vege-
tation stand for each sample.
Due to this and the rarity of
many of the tall shrub species
Figure 1. A diagramatic mountainside
showing how trees of the forest zone
are replaced by low growing scrub
including stunted, twisted Pinus
sylvestris and then by dwarf shrubs on
the high tops, and how British termi-
nology (left columnl differs from that
used in continental Europe (rightcol-
umn).
given above few upland climax
scrub communities have been
described in the NVC. Otherwise,
the tall shrubs are found across a
wide range of different NVC com-
munity types (see Table 2). For
example, luniper is found in
seven woodland, four mire, nine
heath, three maritime and eight
Table 1. Shrubs and trees found in Scottish Montane Scrub.
All seven mountain willows: S. mysinifolia Salisb. (Dark-leaved); S. phylicifolia L. (Tea-leaved); S. lapponum L. (Downy); S. lanata L. (Woolly); Salix arbuscula L. (Mountain); S. mysinites L. (Wortle-leaved) and S. reticulata L. (Net-leaved).
Juniper Juniperus communis ssp communis L. (Upright) and J. communis ssp. alpina Celak. (prostrate)
Dwarf Birch Betula nana L
Tree and shrubs species found above the timberline where these occur in a wind- pruned or stunted shrub-like form such as: Pinus sylvestris L. (Pine); Quercus spp L. (Oak); Betula pubescens Ehrh. (Downy Birch); Sorbus aucuparia L. (Rowan); S. rupicola (Syme) Hedl. (Rock whitebeam) Corylus avellana L. (Hazel); Populus tremula L. (Aspen); Salix aurita L. (Eared Willow) S. capraea var sphacelata Macreight (high altitude Goat Willow)
106
SKÓGRÆKTARRITIÐ 2001 l.tbl.