Fig. 4

The relationship between tree volume growth (iv) and tree volume (v) represented by the iv-v line is steeper for (a) Norway spruce than for (b) European beech and for both species steeper in moist years (e.g., 2001, 2007) than in dry years (e.g., 2003, 2015). For this evaluation we pooled the trees of the monospecific and mixed species plots