Dendrogram of relevés resulting from Ward’s minimum variance clustering, with Euclidean distance as the similarity coefficient. 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.