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

The purpose of this work was to study the landscape characteristics of the forests and woodlands in the Snowdonia National Park, North Wales (UK). Usi ng a geographical information system, several landscape indices were calcul ated 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 t he landscape. Scrub contained many small and similar-sized patches, more re gular in shape. When these habitats were analysed using an edge width of 10 0 m, similar to 99 per cent of the total scrub area was found to lie within edge habitat. Conifer forest presented as a very clumped habitat containin g larger patches with higher variability in size. Objective GIS simulation techniques for ameliorating this fragmentation of the broadleaves, mixed fo rest and scrub were demonstrated using two sites in the Park. Simulations u sing these techniques show that (1) conversion of conifers to broadleaves, (2) reforestation of agricultural land between woodland fragments or (3) cr eating buffer zones around existing woodland would considerably increase th e area of interior or core habitat and connectivity between the presently f ragmented native woodland.