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Table 1 Summary statistics of the continuous variables used in the development of the longitudinal height-diameter models. Statistics for quadratic mean diameter (species specific) and stand age were calculated for sample plot/measurement occasion means, statistics for altitude for sample plot means respectively

From: Longitudinal height-diameter curves for Norway spruce, Scots pine and silver birch in Norway based on shape constraint additive regression models

  Minimum 25%-quantile Median Mean 75%-quantile Maximum
Norway spruce
 dbh (cm) 5.0 11.8 18.1 19.4 25.5 75.5
 Tree height h (m) 1.5 8.6 13.0 13.3 17.4 35.2
 Basal area larger BAL (m2 per 250 m2) 0.0 0.086 0.215 0.281 0.410 2.255
 Quadratic mean diameter qmD (cm) 5.0 11.7 15.4 16.4 20.0 64.3
 Stand age (Y) 2 41 75 79 115 359
 Altitude Alt (m) 2.0 205 355.0 394.1 555.0 1065.0
Scots pine
 dbh (cm) 5.0 15.0 22.2 22.9 29.8 83.1
 Tree height h (m) 1.6 8.5 12.5 12.5 16.0 35.0
 Basal area larger BAL (m2 per 250 m2) 0.0 0.049 0.149 0.197 0.293 1.468
 Quadratic mean diameter qmD (cm) 5.0 16.6 22.2 23.0 28.2 78.4
 Stand age (Y) 1 55 98 92 125 359
 Altitude Alt (m) 0.0 175.0 300.0 350.8 500.0 985.0
Silver birch
 dbh (cm) 5.0 7.6 10.8 12.3 15.3 80.0
 Tree height h (m) 1.9 5.8 7.7 8.4 10.3 30.8
 Basal area larger BAL (m2 per 250 m2) 0.1 0.051 0.130 0.180 0.257 1.704
 Quadratic mean diameter qmD (cm) 5.0 8.5 10.5 11.8 13.6 64.5
 Stand age (Y) 1 48 75 78 105 359
 Altitude Alt (m) 0.0 180.0 340.0 407.6 615.0 1130.0