本研究之目的乃在利用由棲蘭山地區台灣扁柏(Chamaecyparis obtusa var. formosana)皆伐木根株所得之橫斷面圓盤九片為材料,經由樹輪影像分析,建立樹輪寬度,以探討該地區台灣扁柏生長歷程與遭受擾動之時間點,進而推論台灣扁柏可能之更新方式。 經由樹輪寬度年表的比較,本研究顯示九株樣木中有三株建立於西元1000~1100年代,兩株於西元1200~1300年代間建立,一株建立於1550年代,而三株於1750~1800年代建立。由所得的資料推論,研究地點平均每150~200年會有一中或小尺度之擾動,每一次擾動的效應約持續100~200年。此外,由各單株樣木前10年與20年之平均生長推論,該地台灣扁柏更新主要受到小尺度擾動所成之單株或塊狀更新,而非經由大規模更新。本研究證明台灣扁柏可經由小尺度更新之方式維持當地族群,而非僅依靠大規模的擾動來促進更新。
To understand the growth trajectory and the possible regeneration mechanism of Taiwan yellow false cypress (Chamaecyparis obtusa var. formosana), tree-ring images based on the cross-sectioned discs of nine tree stumps from Chilan Shan area of northeastern Taiwan were analyzed. Results suggested that the nine trees were established in four distinctive periods, namely, in 1000~1100’s, 1200~1300’s, 1550’s, and 1750~1800’s. Radial growth chronologies exhibited a series of major to moderate releases about every 100 to 200 years. However, the asynchronous nature of these releases suggests that they were caused by a series of small-scale disturbances. Based on these results and the average growth rates of the first 10 and 20 years of the nine trees analyzed, it is believed that as a whole Taiwan yellow false cypress could maintain its local population via tree-replacement regeneration alone.