A high resolution predictive model for relict trees in the Mediterranean-mountain forests (Pinus sylvestris L., P. nigra Arnold and Abies pinsapo Boiss.) from the south of Spain: A reliable management tool for reforestation

Species which have suffered a contraction of their original distribution in a recent stage of the Earth's history due to climate changes are termed climate relicts. In the Mediterranean basin, one of the most important hotspots of biodiversity in the world, many relict tree species remain in the mountain ranges. The Baetic range, situated in the southeast of the Iberian Peninsula, comprises three of these taxa (Pinus sylvestris L. var. nevadensis H. Christ, Pinus nigra Arnold subsp. salzmannii (Dunal) Franco and Abies pinsapo Boiss.), which grow in enclaves of suitable environmental conditions surrounded by an inhospitable regional climate. A high resolution predictive model for these species was carried out by making a grid of points with a resolution of 250 m, in which twelve explanatory variables were used: four topographical and eight climatic or bioclimatic. This grid also contains information about the presence/absence of the three species involved, which was used as the dependent variable. Then, a modeling process was carried out by means of binary logistic regression. According to the obtained model, climatic and bioclimatic independent variables (especially seasonal rainfall and mean temperatures) are more responsible for species distribution than topographic ones. The final potential distribution was found to be larger than the current one for all three species. This study is able to predict, with a high degree of accuracy, the potential distribution of the three species involved, and it is therefore proposed to implement reforestation programs at small-scale with high resolution (250 m). Other relict tree species from the Mediterranean basin or other places in the world could be modeled in the same way depending on measured variables.