Using focal species modelling to evaluate the impact of land use change on forest and other habitat networks in western oceanic landscapes

Habitat networks have an important role in combating the deleterious effects of habitat fragmentation on biodiversity. This paper demonstrates how focal species modelling can be used to help predict the effects of land use change on habitat networks in western oceanic landscapes. The modelling was applied to the Isle of Mull in Western Scotland using three focal species: Pseudocyphellaria norvegica (Gyeln.) P. James, a lichen of native broadleaved woodland; marsh fritillary (Eurodryas aurinia Rottemburg), a butterfly of damp grassland and song thrush (Turdus philomelos CL Brehm), an avian habitat generalist. Significant areas of planted conifer forest on Mull will be converted to open ground habitat and native woodland. These land use changes, together with modest expansion of native woodland, are predicted to have a positive impact on networks for the lichen and marsh fritillary without unduly compromising networks for habitat generalists. There may be scope therefore for a more ambitious strategy for developing native woodland and damp grassland networks, but further testing using focal species with more exacting ecological requirements is desirable. Focal species modelling has value in informing strategies for land use change and the development of habitat networks provided that care is taken to select species with relevant ecological requirements.