Table 1. Growth characteristics and stress-wave velocity in wood of Betula platyphylla naturally grown in Mongolia and Japan. | |||||||||||||

Site | n | D (cm) | TH (m) | SWV (km s^{–1}) | |||||||||

Mean | SD | Min. | Max. | Mean | SD | Min. | Max. | Mean | SD | Min. | Max. | ||

I | 50 | 13.4 | 2.8 | 9.0 | 21.0 | 11.0 | 2.0 | 7.7 | 14.8 | 3.29 | 0.20 | 2.87 | 3.65 |

II | 30 | 22.7 | 5.1 | 15.4 | 36.7 | 17.6 | 3.3 | 10.3 | 25.8 | 3.76 | 0.48 | 2.62 | 4.44 |

III | 30 | 19.4 | 3.2 | 13.8 | 26.9 | 15.9 | 2.0 | 10.5 | 18.7 | 3.61 | 0.33 | 2.76 | 4.14 |

Mean/total | 110 | 17.6 | 5.4 | 9.0 | 36.7 | 14.1 | 3.8 | 7.7 | 25.8 | 3.50 | 0.39 | 2.62 | 4.44 |

Nikko, Japan | 10 | 17.8 | 2.7 | 13.8 | 21.8 | 17.1 | 2.3 | 14.4 | 21.2 | 4.07 | 0.13 | 3.87 | 4.26 |

Significance | ns | * | ** | ||||||||||

n_{, }number of standing trees; D, stem diameter at 1.3 m above the ground; TH, tree height; SWV, stress-wave velocity of stems; SD, standard deviation; Min., minimum; Max., maximum. Significant differences were obtained by t-test between Mongolian trees (110 trees) and Japanese trees (10 trees). **, significant difference (p < 0.01); *, significant difference (p < 0.05); ns, no significant difference. |

Table 2. Number of annual rings and annual ring width in the sample of 30 Mongolian and 10 Japanese Betula platyphylla trees. | |||||||||

Site | n | Number of annual rings | Annual ring width (mm) | ||||||

Mean | Min. | Max. | Mean | SD | Min. | Max. | |||

I | 10 | 42 | 36 | 54 | 1.42 | 0.21 | 0.23 | 4.28 | |

II | 10 | 83 | 74 | 93 | 1.13 | 0.15 | 0.13 | 3.45 | |

III | 10 | 67 | 62 | 76 | 1.27 | 0.09 | 0.09 | 3.48 | |

Mean/total | - | - | - | - | 1.27 | 0.15 | 0.15 | 3.74 | |

Nikko, Japan | 10 | 54 | 49 | 60 | 1.46 | 0.21 | 0.44 | 3.92 | |

Significance | - | ns | |||||||

n_{,}_{ }number of sample trees; SD, standard deviation; Min., minimum; Max., maximum. Significant differences were obtained by t-test between Mongolian and Japanese samples. ns, no significant difference. |

Table 3. Means and standard deviations of wood properties in the sample of 30 Mongolian and 10 Japanese Betula platyphylla trees. | ||||||||||

Site | n | BD (g cm^{–3}) | CS (MPa) | |||||||

Mean | SD | Min. | Max. | Mean | SD | Min. | Max. | |||

I | 10 | 0.49 | 0.04 | 0.41 | 0.53 | 20.5 | 2.2 | 16.8 | 23.6 | |

II | 10 | 0.55 | 0.02 | 0.51 | 0.58 | 21.3 | 1.1 | 19.4 | 23.9 | |

III | 10 | 0.51 | 0.02 | 0.47 | 0.53 | 19.2 | 1.8 | 16.1 | 21.9 | |

Mean/total | 30 | 0.51 | 0.04 | 0.41 | 0.58 | 20.4 | 1.9 | 16.1 | 23.9 | |

Nikko, Japan | 10 | 0.49 | 0.02 | 0.45 | 0.52 | 21.3 | 1.5 | 18.8 | 23.6 | |

Significance | ** | ns | ||||||||

n_{, }number of sample trees; BD, basic density; CS, compression strength; SD, standard deviation; Min., minimum; Max., maximum. Significant differences were obtained by t-test between Mongolian and Japanese samples. **, significant difference (p < 0.01); ns, no significant difference. |

Table 4. Mean values of basic density in certain radial positions in the sample trees of 30 Mongolian Betula platyphylla trees. | |||||||||

Radial position (annual ring number) | Site I (n = 10) | Site II (n = 10) | Site III (n = 10) | Significance among three sites | |||||

Mean | SD | Mean | SD | Mean | SD | ||||

1–5 | 0.48 | 0.07 | 0.56 | 0.05 | 0.51 | 0.04 | ** | ||

6–10 | 0.46 | 0.06 | 0.53 | 0.05 | 0.49 | 0.03 | ** | ||

11–15 | 0.47 | 0.05 | 0.52 | 0.03 | 0.49 | 0.04 | * | ||

16–20 | 0.48 | 0.05 | 0.52 | 0.03 | 0.49 | 0.03 | ns | ||

21–25 | 0.50 | 0.05 | 0.52 | 0.04 | 0.50 | 0.03 | ns | ||

26–30 | 0.51 | 0.04 | 0.52 | 0.03 | 0.50 | 0.03 | ns | ||

31–35 | 0.52 | 0.03 | 0.53 | 0.03 | 0.51 | 0.03 | ns | ||

n_{,}_{ }number of sample trees; SD, standard deviation; F- and p-values obtained by analysis of variance (ANOVA) test among three sites. **, significant difference (p < 0.01); *, significant difference (p < 0.05); ns, no significant difference. |

Table 5. Correlation coefficients among measured characteristics in the sample of 30 Mongolian Betula platyphylla trees. | ||||||

Property | D | TH | ARW | SWV | BD | CS |

D | ** | * | * | ** | ns | |

TH | 0.696 | ** | ** | ** | ns | |

ARW | –0.450 | –0.587 | ** | * | ns | |

SWV | 0.446 | 0.532 | –0.478 | ** | ns | |

BD | 0.565 | 0.574 | –0.384 | 0.552 | ** | |

CS | 0.101 | 0.151 | –0.144 | 0.221 | 0.499 | |

D, stem diameter at 1.3 m above the ground; TH, tree height; ARW, annual ring width; SWV, stress-wave velocity of stems; BD, basic density; CS, compressive strength; **, significant correlation (p < 0.01); *, significant correlation (p < 0.05); ns, no significant. |