Vulnerability of Pinus cembra L. in the Alps and the Carpathian mountains under present and future climates

Proactive management should be applied within a forest conservation context to prevent extinction or degradation of those forest ecosystems that we suspect will be affected by global warming in the next century. The aim of this study is to estimate the vulnerability under climate change of a localized and endemic tree species Pinus cembra that occurs in the alpine timberline. We used the Random Forest ensemble classifier and available bioclimatic and ecological data to model present and future suitable areas for P. cembra and estimate its current and future vulnerability. Future projections for years 2020, 2050 and 2080 were simulated using two IPCC Special Report on Emission Scenarios run under four global climate models.The suitability model described the optimal environmental conditions for P. cembra. Model scores (κ = 0.77, sensitivity = 0.99 and specificity = 0.80) are robust. The main factors defining the model were Kira's warmth index and summer temperatures. Results show that there is potential for P. cembra to regenerate and persist in currently suitable areas. Future trends analysis suggested a cumulated mean loss of suitable areas of between 53% and 72% for different scenarios. All modeled projections predicted an upslope shift of the optimally suitable P. cembra belt and no downslope shift. We discuss environmental factors/plant interactions, the theoretical assumptions behind the model, model strengths and limitations, and we highlight the conservative traits of our analysis. The results suggest that forest management practices will play a fundamental role in the conservation of P. cembra habitats in the Alps.