Fig. 3
Stand volume growth in the monospecific and mixed-species stands of Norway spruce and European beech of the Kranzberg forest experiment from 1998 to 2016 shown in relation to stand age and in relation to water availability (de Martonne index for the growing season, Mgs). Upper panel: Annual stand volume growth of Norway spruce and European beech for (a) the mono-specific stands and (b) total and species stand volume growth in the mixed-species stand. Lower panel: Annual stand volume growth dependent on the Martonne index shown for (c) the mono-specific stands of Norway spruce and European beech and (d) the total and species specific stand volume growth in the mixed-species stands. Note that in (d) the species specific growth values have been converted into ha-values by dividing them by their area share in the mixed stand