Map of the potential distribution of the four main groups of relevés resulting from random forest procedure. Cluster A1 Corylus avellana forests. Cluster A2 Ostrya carpinifolia-Fagus sylvatica forests. Cluster B lower montane thermophytic Fagus sylvatica forests. Cluster C middle montane, slightly acidic Fagus sylvatica forests. Cluster D upper montane basiphytic Fagus sylvatica forests. Cluster E middle montane basiphytic Fagus sylvatica forests. Cluster F upper-montane acidophytic Fagus sylvatica forests.