Mean height or dominant height – what to prefer for modelling the site index of Estonian forests?

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Height curve statistics specifications for Table 2_

Height curve statistics
n – number on dominant trees;
me – arithmetic mean residual hmeasured – hpredicted (systematic error);
sde – quadratic mean residual hmeasured – hpredicted (random error);
p-value – t-test for hypothesis that mean residual is different from zero;
desc – despite excluding outliers and a moderate number of observations (n ≥ 16) in each cohort, the height curve was descending (parameter a < 0 for models 2 and 3, parameter b < 0 for model 4) in the case of some cohorts.

Values of species-specific coefficients for height curve models 4, 5 and 6_

Model	Coefficient	Scots pine	Norway spruce	Silver birch	Other deciduous
5	asp	0.30201	0.44325	0.27936	0.27936
6	asp	0.32044	0.44103	0.39554	0.25803
6	bsp	0.00434	0.00643	0.00629	0.00582
4, 6	csp	1.48076	1.37255	1.32998	2.04430

Species-specific coefficients for regression model (9)_

Coefficient	Scots pine	Norway spruce	Silver birch	Other deciduous
a0	2.0494	3.3661	3.0474	1.7910
a1	−0.0964	−0.1231	−0.0824	−0.1108
a2	−15.686	−14.070	−34.854	−15.215

Fit statistics of the height curve models (2–6) for dominant trees based on experimental data_ (n – number of trees; me – mean residual; sde – mean square residual; p-value – p-value of t-test; desc – number cohorts with a descending height curve)_

Statistic	Scots pine	Norway spruce	Silver Birch	Other deciduous	All species
n	5165	914	426	76	6581
Model (2) me	−0.08	−0.17	−0.18	−0.23	−0.10
Model (2) sde	1.37	1.18	1.38	1.41	1.35
Model (2) p-value	<0.001	<0.001	0.008	0.165	<0.001
Model (2) desc	5	0	1	0	6
Model (3) me	−0.07	−0.13	−0.15	−0.21	−0.09
Model (3) sde	1.37	1.18	1.38	1.40	1.35
Model (3) p-value	<0.001	0.001	0.025	0.188	<0.001
Model (3) desc	5	0	1	0	6
Model (4) me	−0.01	−0.08	−0.11	0.01	−0.03
Model (4) sde	1.37	1.17	1.37	1.35	1.34
Model (4) p-value	0.602	0.044	0.113	0.937	0.127
Model (4) desc	5	0	1	0	6
Model (5) me	−0.09	−0.61	−0.14	−0.44	−0.17
Model (5) sde	1.47	1.45	1.51	1.49	1.47
Model (5) p-value	<0.001	<0.001	0,060	0,009	<0.001
Model (6) me	−0.03	−0.05	−0.23	0.02	−0.04
Model (6) sde	1.47	1.32	1.52	1.37	1.45
Model (6) p-value	0.142	0.301	0.002	0.896	0.013