The Possibility of Using the Chapman–Richards and Näslund Functions to Model Height–Diameter Relationships in Hemiboreal Old-Growth Forest in Estonia

In light of the difficulties in stand volume estimation natural forests, we analyzed height–diameter relationships and derived a set height equations for naturally developing forest ecosystems, using Järvselja old-growth Laeva commercial Estonia as case study. This contribution presents an approach to model individual tree Scots pine, common aspen, silver downy birch, Norway spruce, black alder, gray linden species, European ash, maple, deciduous species coniferous multi-size mixed-species stands Estonia. Single-tree-level data were collected 2013. Two methods used obtain stand-level data: whole surface inventory partial inventory. To relationship developed order predict single based on observed diameter at breast height, applied nonlinear mixed models where Chapman–Richards Näslund fixed-effects influence sites random effects. The followed criteria: (1) starts h = 1.3; d 0; (2) functions are monotonically increasing with clear inflection point 3) fixed-effect has asymptotic value) forest.