Response of British lichens to climate change scenarios: Trends and uncertainties in the projected impact for contrasting biogeographic groups

Projection of species-response to climate change scenarios is a key tool in conservation strategy. Previous studies have projected climate change impacts for animal and vascular plant species using the 'bioclimatic envelope' approach. In this study we apply the principles of the bioclimatic envelope approach to examine the response of 26 lichen species whose distributions are well characterised within the British Isles. Lichen species were subjectively selected based on their contrasting distributions, and their ecological traits, which fulfilled as closely as possible the assumptions of the bioclimatic envelope method. We used a split-sampling approach to model the species-response to present-day climate using confirmed records and pseudo-absences as input data, and testing each model against an 'independent' calibration dataset. Predictive models were projected using standard climate change scenarios comprising the UKCIP02 data. Projections indicate broad trends in the response of species placed into contrasting biogeographic groups, and point to the potential for significant change in the spatial distribution of the British lichen flora. We highlight putative threats to montane and Boreal elements of the lichen flora, and emphasise significant uncertainty in projected response of the UK's internationally important oceanic flora.