3.2.1. Current Models

The analysis of single variable contribution showed that temperature seasonality, mean temperature of wettest quarter and precipitation of driest month were the main factors influencing the model performance for all the tree species. We found that the accumulated contribution of these three variables was 88%, 83%, 93% and 81% for *P. mugo*/*uncinata*, *P. nigra*, *P. sylvestris* and *Q. pubescens*, respectively. The current model predicted a high probability of potential distribution of *P. mugo*/*uncinata* especially in the Alps and other European mountain areas, whereas *P. nigra* was more likely to occur in central and southern Europe and in western Asia, *P. sylvestris* in central and northern Europe and in western Asia and *Q. pubescens* in central and southern Europe (Figures 3 and 4).

**Figure 3.** Ecological Niche Models for *P. mugo*/*uncinata* (**a**), *P. nigra* (**b**), *P. sylvestris*(**c**) and *Q. pubescens* (**d**) using current scenario. Scales show the probability of presence ranging from 0 to 1.

**Figure 4.** Ecological Niche Models for *P. mugo*/*uncinata* (**a**), *P. nigra* (**b**), *P. sylvestris*(**c**) and *Q. pubescens* (**d**) using the current scenario. Binary map shows: 0 = unsuitable habitat; 1 = suitable habitat.
