Table 1. Significant variables, their coefficients and significance, and main statistics for developed equations of height increment of hybrid aspen based on weather variables and duration of growth (as HI = ax_{1} + bx_{2} +...+ intercept, where x1, x2 etc. are the significant parameters and a, b, etc. are coefficient values) showing the best fit to HI. Equations for data of 2010, 2011 and both years are shown. PET – potential evapotranspiration. | ||||||||

Early leaf flushing | ||||||||

2010 | 2011 | Both years | ||||||

Variable | Coeff. | p-value | Variable | Coeff. | p-value | Variable | Coeff. | p-value |

Intercept | 0.142 | 0.719 | Intercept | –1.908 | 0.023 | Intercept | –0.782 | 0.060 |

Mean temp. | 0.116 | <0.001 | Mean temp. | 0.274 | <0.001 | Mean temp. | 0.192 | <0.001 |

Temp. sum ( > 5 °C) | –0.003 | 0.033 | Temp. sum ( > 5 °C) | –0.007 | 0.038 | Temp. sum ( > 5 °C) | –0.007 | <0.001 |

Day of growth | –0.006 | 0.032 | ||||||

AIC | –29.2 | –19.97 | –38.69 | |||||

F-statistic | 16.51 | 15.94 | 24.15 | |||||

R-squared | 0.81 | 0.69 | 0.62 | |||||

Adjuster R-squared | 0.76 | 0.65 | 0.59 | |||||

Residual standard error | 0.34 | 0.53 | 0.53 | |||||

Intermediate leaf flushing | ||||||||

2010 | 2011 | Both years | ||||||

Variable | Coeff. | p-value | Variable | Coeff. | p-value | Variable | Coeff. | p-value |

Intercept | –0.684 | 0.061 | Intercept | –1.201 | 0.186 | Intercept | –1 | 0.026 |

Mean temp. | 0.159 | <0.001 | Mean temp. | 0.396 | <0.001 | Mean temp. | 0.208 | <0.001 |

Temp. sum ( > 5 °C) | –0.005 | 0.002 | Solar radiation | 1.165 | 0.004 | Temp. sum ( > 5 °C) | –0.007 | <0.001 |

PET | –3.409 | 0.003 | ||||||

AIC | –27.62 | –20.66 | –34.62 | |||||

F-statistic | 21.89 | 15.47 | 24.74 | |||||

R-squared | 0.78 | 0.77 | 0.62 | |||||

Adjuster R-squared | 0.75 | 0.72 | 0.6 | |||||

Residual standard error | 0.36 | 0.51 | 0.57 | |||||

Late leaf flushing | ||||||||

2010 | 2011 | Both years | ||||||

Variable | Coeff. | p-value | Variable | Coeff. | p-value | Variable | Coeff. | p-value |

Intercept | –1.082 | 0.009 | Intercept | –1.169 | 0.265 | Intercept | –0.312 | 0.617 |

Mean temp. | 0.174 | <0.001 | Mean temp. | 0.489 | <0.001 | Mean temp. | 0.337 | <0.001 |

Temp. sum ( > 5 °C) | –0.005 | 0.006 | PET | –4.475 | 0.002 | PET | –3.354 | 0.003 |

Solar radiation | 1.389 | 0.006 | Solar radiation | 1.038 | 0.005 | |||

AIC | –26.02 | –12.76 | –22.75 | |||||

F-statistic | 23.6 | 12.18 | 12.81 | |||||

R-squared | 0.8 | 0.72 | 0.57 | |||||

Adjuster R-squared | 0.76 | 0.66 | 0.53 | |||||

Residual standard error | 0.38 | 0.64 | 0.67 |