Fragmented native woodlands in Snowdonia (UK): Assessment and amelioration

Abstract

The purpose of this work was to study the landscape characteristics of the forests and woodlands in the Snowdonia National Park, North Wales (UK). Using a geographical information system, several landscape indices were calculated for the broadleaves, conifers, mixed high forest and scrub vegetation categories. A total of 3967 woodland fragments, covering an area of 216 664 ha, were analysed in terms of their area, density, degree of isolation and shape in order to understand their spatial distribution and connectivity. The analyses showed that the broadleaved habitat is dissected into a great number of patches, irregular in shape and with a mean patch size of <4 ha. Fragments of mixed forest had similar sizes and were more isolated across the landscape. Scrub contained many small and similar-sized patches, more regular in shape. When these habitats were analysed using an edge width of 100 m, ∼99 per cent of the total scrub area was found to lie within edge habitat. Conifer forest presented as a very clumped habitat containing larger patches with higher variability in size. Objective GIS simulation techniques for ameliorating this fragmentation of the broadleaves, mixed forest and scrub were demonstrated using two sites in the Park. Simulations using these techniques show that (1) conversion of conifers to broadleaves, (2) reforestation of agricultural land between woodland fragments or (3) creating buffer zones around existing woodland would considerably increase the area of interior or core habitat and connectivity between the presently fragmented native woodland.