Skógræktarritið - 15.05.2001, Side 136

Table 1. Examples of the NWM decision rules.
Geology and parent material' Soils' Terrain' Existing Vegetation2 Predicted NVC Woodland Class
Glacial till derived from acid rocks Peaty podzols Non-rocky hill slopes Calluna vulgaris dominant Scots pine woodland with heather (W18)
Colluvium derived from acid rocks Podzols Steep valley slopes, often rocky Acid Agrostis- festuca grassland, bracken scrub W17/W11 interchangeable category
Moraines derived from acid rocks Peaty podzols, peat Moundy moraine Calluna vulgaris and blanket bog Scots pine with heather (W18) and scattered woodland on peat mosaic
Note:
1 from 1:250 000 scale soil map
2 from 1:25 000 scale land cover map
detail by Rodwell (1991) and
Rodwell & Paterson (1994). This
available guidance was consid-
ered to inadequately cover the
sub-alpine scrub zone and the
wet, often Moíim'a-dominated
moorland communities, so fur-
ther consideration was given to
them. Three categories of wood-
land have been identified and
mapped:
1. Where possible, single NVC
woodland communities.
2. Mosaics of woodlands where an
area has variable site condi-
tions. Different woodland
communities are matched to
the different soil types.
3. \nterchangeable categories,
where two woodland commu-
nities are considered to be
equally suited to the site con-
ditions.
The key to the modelling
process is the interpretation
required to 'translate’ between
the woodland requirements, as
expressed in the literature, and
the site characteristics as they are
represented in the integrated
dataset. Table 1 contains exam-
ples of the type of decision rule,
which links different woodland
categories with different sites,
used in the model.
APPLICATIONS AND PRACTI-
CAL USES
Scottish Natural Heritage, indi-
vidually or in partnership with
other organisations, are the prin-
cipal users of the output generat-
ed by the Native Woodland
Model. Their use of the output is
primarily as a strategic planning
tool in a number of applications
and geographic areas (Figure 1).
To date, the uses of the model
are as follows:
I. Case studies.
The combined NWM and FHN
approach -the model output
acting as a template on which
the network can develop - has
been used in a number of areas.
These include:
The Atlantic oakwoods of'Nestern
Scotland. These are internationally
recognised for their biodiversity
benefits and there are strong
aspirations and commitments to
restore them around Loch Awe in
Argyll and to expand them at
Loch Sunart in Ardnamurchan.
The NWM indicates that sites
suited to oak woodland are
restricted to the steep narrow
lower slopes around both lochs.
These contain relatively fertile
and freely drained mineral soils.
These sites are also valuable for
agriculture and coniferous
forestry and difficult judgements
must be made to achieve the
appropriate land use balance.
Opportunities for 'restructuring'
the coniferous woodland - for
example, creating more diversity
using native broadleaved species
when it reaches the thinning or
clear-fell stages - are identified
by the model.
The Island ofRum. Scottish Natural
Heritage wish to restore wood-
land to the island of Rum to
enhance natural biodiversity.
This requires woodland on a
scale which supports natural
processes and within a timescale
of approximately 50 years. SNH
research indicates that a range of
woodland patch sizes (3 -100 ha)
and woodland structures (blocks
and lightly wooded land) will be
required to achieve this. Because
of the lack of viable seed sources,
planting is the only realistic
option. The NWM has been used
to provide guidance on the plant-
ing scheme both in terms of the
species choice and the location
and pattern of the different com-
ponents of the network.
The Cairngorms Partnership Area.
The NWM has been used as the
basic zoning tool in the recently
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SKÓGRÆKTARRITIÐ 2001 l.tbl.