Table 1. Calibration data. Mean, standard deviation (SD) and maximum values of some plot characteristics, at the first measurement, by stand type. | |||||||||||||||

Stand type | Site index*, m | Density, stems ha^{–1} | Age, years | Mean height**, m | |||||||||||

Mean | SD | Max | Mean | SD | Max | Mean | SD | Max | Mean | SD | Max | ||||

Scots pine (N = 899) | 20.2 | 4.0 | 32 | 2679 | 1063 | 6000 | 21.8 | 4.4 | 38 | 3.6 | 2.0 | 13.4 | |||

Norway spruce (N = 498) | 24.7 | 5.3 | 36 | 2645 | 1026 | 5800 | 21.2 | 3.7 | 38 | 4.3 | 2.2 | 15.4 | |||

* Site index according to site properties (Hägglund and Lundmark 1977) ** Height weighted mean height |

Table 2. Calibration data. Mean, standard deviation (SD) and maximum values of some tree characteristics, at the first measurement, by tree species. | |||||||||||

Tree species | Tree height (h), m | ih* _{5} | hc** _{i} | ||||||||

Mean | SD | Max | Mean | SD | Max | Mean | SD | Max | |||

Scots pine (N = 10201) | 3.9 | 2.4 | 15.6 | 1.8 | 0.8 | 6.3 | 26.2 | 30.5 | 345 | ||

Norway spruce (N = 8163) | 4.0 | 2.7 | 19.2 | 1.9 | 1.1 | 6.0 | 38.7 | 41.1 | 349 | ||

* ih = Height increment for the 5-year period_{5}** hc = Distance-independent competition index (Table 6) _{i} |

Table 3. Validation data. Mean, standard deviation (SD) and maximum values of some plot characteristics, at the first measurement, by tree species. | |||||||||||||||

Site index*, m | Density, stems ha^{–1 } | Age, years | Mean height**, m | ||||||||||||

Mean | SD | Max | Mean | SD | Max | Mean | SD | Max | Mean | SD | Max | ||||

Scots pine (N = 224) | 24.5 | 3.4 | 31.2 | 2770 | 1790 | 18430 | 26 | 9 | 50 | 6.5 | 2.7 | 14.3 | |||

Norway spruce (N = 83) | 32.2 | 4.8 | 38.4 | 2540 | 1480 | 8370 | 23.5 | 6 | 38 | 7.1 | 2.4 | 12.3 | |||

* Site index according to site properties (Hägglund and Lundmark 1977) ** Height-weighted mean heigh |

Table 5. Parameter estimates for height growth models for individual trees in young stands of Scots pine and Norway spruce in Sweden. Dependent variable ih, m. For variable explanation, see Table 6. _{5} | ||||

Pine, n = 10201 | Spruce, n = 8163 | |||

Variable | Parameter | SEE ^{b} | Parameter | SEE ^{b } |

constant | –1.6474 | 0.05294 | –3.3560 | 0.08291 |

h | –0.1213 | 0.004164 | –0.1431 | 0.004974 |

ln(h) | 0.5728 | 0.01549 | 0.6222 | 0.04098 |

hc/(0.1 + _{i}h) | –0.01329 | 0.000583 | –0.02013 | 0.000783 |

ln(h × H) _{h} | - | - | 0.1384 | 0.02559 |

H/_{h}T | 0.7810 | 0.07038 | 0.2905 | 0.08202 |

ln(SI) | 0.6522 | 0.01846 | 1.0804 | 0.02678 |

Newcl | - | - | 0.03032 | 0.006996 |

Spcult | - | - | 0.09691 | 0.008062 |

estimated variance components | ||||

0.07545 | 0.08246 | |||

0.2254 | 0.3325 | |||

^{b} standard error of estimate |

Table 6. Symbols for variables used in height increment models. | |

Variable | Definition and units |

ih_{5} | Single tree 5-year height increment, m |

h | Initial tree height, m |

H_{h} | Height-weighted mean height, Σh^{2}/Σh, of all trees on the plot, m |

T | Stand age, expressed as basal area-weighted total age in the plot, years |

hc_{i } | Distance-independent competition index, sum of the height square (Σh^{2}) ×0.1 of all trees taller than the subject tree in the plot (100 m^{2}). |

Newcl | Indicator variable for pre-commercially thinned plots. Newcl = 1 if the plot was cleaned within 10 years before the measurement, otherwise Newcl = 0 |

Spcult | Indicator variable for spruce establishment by planting. Spcult = 1 if the plot was planted with spruce, otherwise Spcult = 0 |

SI | Site index (m), according to site properties (Hägglund and Lundmark 1977) |