Projected climate change impacts on upland heaths in Ireland

Heathland habitats in Ireland occur primarily in an oceanic setting which is strongly influenced by changes in the climate. Because of the oceanic environment, Ireland has a high proportion of the northern Atlantic wet heaths and alpine and boreal heaths of high conservation value within Europe. Future climate change is widely expected to place additional pressure on these systems. Seven bioclimatic envelope modelling techniques implemented in the BIOMOD modelling framework were used to model wet heath and alpine and boreal heath distributions in Ireland. The 1961-1990 baseline models closely matched the observed distribution and emphasise the strong dependency on climate. Mean winter precipitation, mean winter temperature and elevation were found to be important model components. The fitted model's discrimination ability was assessed using the area under the curve of a receiver operating characteristic plot; the true skill statistic; and Cohen's kappa. A BIOMOD ensemble prediction from all the models was used to project changes based on a climate change scenario for 2031-2060 dynamically downscaled from the Hadley Centre HadCM3-Q16 global climate model. The climate change projections for the individual models change markedly from the consistent baseline predictions. Although the consensus models project gains in climate space for both habitats in other parts of the country, new habitat formation in these areas is unlikely, as current (and hence near-future) land use and other conditions are not likely to favour expansion.