Fig. 2From: A generalized self-thinning relationship for multi-species and mixed-size forestsPreliminary results for single species. Global criterion (presented in Eq. 9) for different values of α for oaks (Quercus sp.) (a) against all other species. An optimum region (i.e., minimum in dark gray) is clearly visible. A similar result is obtained for beech (F. sylvatica) (b). On the contrary, spruce (P. abies) (c) and whitebeam (S. aria) (d) do not show optimum valueBack to article page