| 摘要: | 本分析旨在瞭解溪頭台灣杉生長量試驗(Growth study on Taiwania cryptomerioides Hayata at Chi-Tou)經過68年的林木生長與林分發育之林木存活與胸徑生長。結果顯示，溪頭台灣杉生長量試驗（佔地0.28ha）的林木存活數目86株，存活率40.67%，胸高斷面積23.1123平方公尺，理論胸徑58.50cm，平均胸徑56.12±3.56cm，其中最大胸徑104.72 cm，最小胸徑21.33 cm，相差幾達5倍。胸徑在30cm（含）以上時計有林木84株，株數百分比97.67%，胸高斷面積23.0150平方公尺，平均胸徑56.87cm；胸徑在60cm（含）以上時計有林木36株，株數百分比41.86%，胸高斷面積15.1266平方公尺，平均胸徑72.50cm；胸徑在90cm（含）以上時計有林木3株，株數百分比3.49%，胸高斷面積2.2663平方公尺，平均胸徑97.93cm；而大於平均胸徑(56.12cm)（含）以上之林木有39株，株數百分比45.35%，平均胸徑71.35cm，胸高斷面積15.9075平方公尺。林木依照胸徑大小可劃分成七個等級，經卡方檢定，各胸徑階之林木數目呈常態分佈。
This study investigated DBH analysis of growth study on Taiwania (Taiwania cryptomerioides Hayata) at Chi-Tou for age 68. Results showed that survival tree number was 86, survival percentage was 40.67%, basal area was 23.1123m^2, theoretical DBH was 58.50 cm, average DBH was 56.12±3.56 cm, among them maximum DBH was 104.72 cm, minimum one was 21.33 cm. The survival tree number, survival percentage, basal area, and average DBH of trees with DBH not less than 30cm were 84, 97.67%, 23.0150 cm^2, and 56.87cm, respectively. The survival tree number, survival percentage, basal area, and average DBH of trees with DBH not less than 60cm were 36, 41.86%, 15.1266cm^2, and 72.50cm, respectively. The survival tree number, survival percentage, basal area, and average DBH of trees with DBH not less than 90cm were 3, 3.49%, 2.2663cm^2, and 97.93cm, respectively. However, the survival tree number, survival percentage, basal area, and average DBH of trees with DBH not less than average DBH (i.e. 56.12cm) were 39, 45.35%, 15.9075cm^2, and 45.35cm, respectively. According to their size, 7 DBH classes have been divided. The number of tree in each DBH class did show normal distribution after chi-square test. |
