South West Scotland forest habitat network

Background

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The study area, defined by the Unitary Authority boundaries (see map on right) with a 5km buffer applied to the external boundary, is approximately 1.5 million hectares (20,200ha of the area is in England).

The following UK Biodiversity Action Plan (BAP)�priority woodland types occur in south west Scotland:

Upland mixed ash woodland
Upland oak woodland
Wet woodland
Upland birch woodland
Lowland mixed broadleaved woodland.�

The river, gorge and riparian networks contain the main wooded areas of the Clyde Valley,�whilst Dumfries & Galloway contains important examples of old sessile oak woodland and Tilio-Acerion forest.�

This�study focused on the broadleaved woodland components�as the priority woodland habitats for the conservation of woodland biodiversity within the context of the wider forest landscape.

Objectives

In south west Scotland,�identify:

The quantity, size�and location of�broadleaved woodland specialist networks
The quantity, size and location of high quality broadleaved woodland specialist networks
Species rely on these networks
The constraints to woodland expansion.

Methods

Experts were asked to evaluate individual woodland blocks by broadly assessing the woodland structure, deadwood and field layer components, to enable a biodiversity quality classification�to be made for�each block.
A Forest Research model from BEETLE (Biological and Environmental Evaluation Tools for Landscape Ecology) was used to group woodlands that share several habitat characteristics, and to model the dispersal permeability of all the non-habitat land-cover components of the matrix.
In view of the priority habitats�of�sout west�Scotland,�the focus was the range of�broadleaf woodland specialist focal species considered as moderately mobile, not sensitive to habitat patch size, and sensitive to woodland edge.
Core areas of broadleaved woodland were identified in a GIS using the Scottish Semi-natural Woodland Inventory (SSNWI) and National Inventory of Woodland and Trees (NIWT) data to produce polygons of contiguous areas of woodland identified as having an 80% or more broadleaved component and a 50% or more�canopy cover.
A 50m�woodland edge was removed�from the core habitat�areas where the habitat did not connect with other woodland. The�woodland edge was added to the non-habitat matrix with a permeability value�of 1 (low value�equal�highly permeable).