Skógræktarritið - 15.05.2001, Page 110

three metres tall would provide
considerable shelter, to walkers
as well as deer and sheep, during
bad weather.
Restoration issues
MacKenzie (2000) recently re-
ported on the collation of all
existing records for low alpine,
subalpine and coastal scrub
communities in Scotland. He
reports a variable level of infor-
mation available for scrub sites,
ranging from presence or
absence in a ten-kilometre
square to a full site description
with a map. The majority of re-
cords fall in between, reporting
presence or absence for a four or
six figure ordnance survey grid
reference, information which
does not allow any assessment
of population trends or the via-
bility of individual communities.
Despite the variation in informa-
tion the dataset provides a useful
tool for initial work to prioritise
restoration activity. It also indi-
cates where there is a need for
further field work to increase
knowledge of the scrub commu-
nities in order to better focus
resources.
A recent condition survey
(Marriott, 1994) of thirteen of the
remaining thirty-two sites for
Salix lanata showed that in at
least three sites it was ecologi-
cally extinct, having only one sex
present, and that the small num-
ber of plants surviving at several
others brought into question
their viability. A similar survey
forS. lapponum (Ross, 1996) failed
to relocate the plant at four out
of fifteen sites in the sample.
Data for B. nana by MacKenzie
(2000) shows that a number of
sites, particularly in the west,
have not been recorded since the
1970's. This growing body of evi-
dence suggests that these tall
shrub communities are under
continuing pressure and that
action is urgently required to halt
their demise.
From the start the principle
method of establishing forest
areas employed by the Forestry
Commission has been through
planting and the exclusion of
larger herbivores by fencing. This
practise is increasingly being
challenged in projects where the
aim is to generate natural her-
itage benefits. Fencing is a barri-
er to movements of animals, and
man, and is a danger to the
native woodland grouse Tetrao
tetrk L. (Black Grouse) and Tetrao
urogallus L. (Capercaille) both of
which are in serious decline.
However, the former particularly,
could benefit substantially from
an expansion of the scrub habi-
tats that border high forest. This
illustrates the dilemma facing
restorative efforts within the con-
text of overgrazing when culling
is politically contentious.
The Royal Society for the
Protection of Birds (RSPB), and
the Government advisers on
Natural Heritage, Scottish
Naturai Heritage (SNH), have
recently regenerated areas of
native birch and pine forest with-
out the use of fences, relying on
a significantly reduced deer pop-
ulation, achieved through
culling. However, many montane
scrub populations exist in high
calcareous valleys where the
ground vegetation provides high
quality browse. The current
imbalance between the size of
the remnant plant populations
and the numbers of deer is such
that it is unclear whether it is
possible to restore these scrub
communities in the presence of
any deer.
Demonstration fencing under-
taken through the MSR Project
has raised questions about the
practicality of fencing inside high
mountairr/valleys to protect
plants gfówing on unstable
slopes. Very high levels of fence
maintenance were required to
mend severe damage each suc-
cessive winter, even when the
wires were removed over the win-
ter period. The resource require-
ments for such action are beyond
the commitment of a private
estate and the current levels of
government incentive, to be pro-
moted as a serious solution.
The classic site for tall moun-
tain willows is at the top of an
inaccessible cliff, on the wall of a
steep hanging valley, or on wet,
unstable slopes. Where they
might be reached they show
signs of browsing (Marriott,
1997). They grow at their most
lush along inaccessible stream
gorges or on broad cliff ledges. In
such situations they are exposed
to rockfall, landslip, avalanche
and ice plucking and there is
annual evidence of the toll this
takes on the communities at the
sites visited regularly. It is also
likely that these ‘typical' mon-
tane scrub habitats are only the
marginal sites that have been left
since an increase in grazing fol-
lowing the introduction of sheep
to the hills in the nineteenth
century (Mardon 1990), has erad-
icated these communities from
more suitable sites.
Both willows and luniper are
dioecious. There are a number of
colonies of both types which are
single sexed and could be con-
sidered ecologically extinct.
When both sexes are present
casual observation suggest that
it is important that they are with-
in 50m of each other (Marriott,
1997) for effective pollination by
their main pollinators - bumble-
bees. For many colonies there is
no information available on
which to base an assessment of
long term viability.
As interest in indigenous
native woodlands has grown,
there has been greater under-
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SKÓGRÆKTARRITIÐ 2001 l.tbl.