Forecasting the circum-Mediterranean firs (Abies spp., Pinaceae) distribution: an assessment of a threatened conifers’ group facing climate change in the twenty-first century

This study examines 10 different taxa within the genus Abies identified in the circum-Mediterranean area: A. alba, A. borisii-regis, A. cephalonica, A. cilicica, A. nebrodensis, A. nordmanniana subsp. equi-trojani, A. nordmanniana subsp. nordmanniana, A. numidica, A. pinsapo var. marocana and A. pinsapo var. pinsapo. We assess the potential distribution of these species in the Mediterranean Basin, most of Central-Northern Europe and Asia Minor through analysis of 8 bioclimatic variables. First, the potential distribution (suitability area) was calculated with Biomod2 package for R using 10 algorithms. Models were ensembled for the present period and then projected into two climate change scenarios (an intermediate and the most extreme) within two time slices (2041–2060 and 2081–2100) and two Global Circulation Models (GCMs). The analysis showed an increase in total suitable area under both forecasted scenarios. Abies spp. appeared to be resilient against climate change, showing a latitudinal and longitudinal migration trend in response to the loss of current habitats. A proposal of assisted migration (managed relocation) is suggested as an interesting alternative to guarantee the preservation of the most endangered species by promoting the establishment of new populations outside of their historical distribution area.