Fig. 5

Climatic, edaphic and stand structural variables significantly (p < 0.05) correlating with the axes 1 and 2 of the DCA ordination space calculated with the tree species’ relative basal area (B.A. in %) in the plots. The relationships are indicated by the direction of arrows, the strength of correlation (R²) by the arrow lengths. Symbol position was slightly adjusted to avoid overplotting. For variable units of climate, forest stand, organic layer and soil, see Table 2 and for full names with explanations Table 11 in Appendix. Plot (a) shows the tested climatic and stand structural variables, plot (b) the organic layer and mineral soil variables. The plots in (a) are coloured according to the dominant tree species (grouped into four forest types according to dominant species (beech forest: F. sylvatica B.A. > 66.6%, oak forest: Quercus spp. B.A. > 66.6%, linden forest: T. tomentosa B.A. > 66.6%; mixed forests: all other species combinations). The plots in (b) are coloured according to the percentage of F. sylvatica in the total basal area, indicating the linear shift towards beech dominance along ordination axis 1