Fig. 6. Numerical classification (Ward's method with the Euclidean distance measure) of relevés from three sets (Hadač, Sofron, 1980;Matějka, 1994; data obtained during course of monitoring under ICP-Forests) on the basis of the species covers in the herb layer. Several groups of communities were distinguished well: Qw some species rich oak forests, Qc oak forests with Calamagrostis arundinacea, g3+4 communities of classification groups 3 and 4 (Matějka, 1994), g5 communities of classification group 5 (Matějka, 1994), A-Q ass. Abieto-Quercetum (man-influenced forests), cover<5% coniferous stands with total cover of herb layer less then 5%, L-Q ass. Luzulo albidae-Quercetum (man-influenced forests), A-Pin1 ass. Avenello flexuosae-Pinetum, A-Pin2 ass. Avenello flexuosae-Pinetum (prevailing part of stands in South Bohemia).