Fig. 5From: Analysing the effect of stand density and site conditions on structure and growth of oak species using Nelder trials along an environmental gradient: experimental design, evaluation methods, and resultsGraphical illustration of the non-linear smoothers f 1 − f 3 from eq. 4 for tree height as the dependent variable. Straight line: estimate, dashed lines: 95 % confidence area; DCI = Hegyi-indexBack to article page