溪頭地區臺灣杉人工林不同林齡胸徑與樹高生長之研究

為了解逾百年生之臺灣杉人工林胸徑與樹高生長，調查臺大實驗林溪頭地區8、17、28、47、74年生臺灣杉人工林與庭園木。結果顯示：溪頭地區辦公室前的庭園木，為目前記錄最老的臺灣杉人工林，部分呈現孤立木狀態，最大胸徑與最大樹高的臺灣杉都屬於庭園木；受到生長變異的影響，這少數高齡的樣木能作為生長參考，不適合置入林分層級統計。回顧相關文獻與現況調查，臺灣杉人工林的胸徑與樹高初期生長快速，至70年生以後，無論是林分胸徑、林分樹高或蓄積量皆較溪頭地區柳杉長期試驗地紀錄佳。併入文獻數據後，Gompertz生長曲線所擬合的胸徑漸進線與反曲點時間都縮減，但曲線形狀未有明顯的衰老期部份，由此推論逾70年生的臺灣杉生長胸徑勢開始趨緩的證據仍嫌不足，但樹高生長由55至74年生，近20年的林分樹高生長量僅5 m左右，生長率與生長曲線上都有明顯趨緩現象；各林齡的樹高曲線隨林齡具規律性的變化，受到各林齡間不平等的數據加權比重影響，合併各林齡數據配置出的樹高曲線，所推估出的數值有不合理的偏差，建議使用樹高曲線推估時，除了考量到林齡與樣本值全距的限制，還須合理的樹高曲線形狀。

關鍵字

樹高；胸徑；臺灣杉人工林

並列摘要

In understanding the growth of diameter breast height (DBH) and tree height (H) of Taiwania, this study investigated Taiwania plantations of different ages in Xitou area. The results show that the garden Taiwania trees in front of Xitou office are in individual state and demonstrates highest DBH and H. Affected by growth variation, these samples can be taken as a reference but not suitable for stand-level statistics. According to literature and investigation, Taiwania after 70-year-old growing fast, DBH, H, and volumes are better than Japanese cedar. Incorporating with Gompertz model, DBH growth curve asymptote and inflection point time are reduced, but the shape doesn't show aging period obviously. Therefore, no sufficient evidences support the growth of 70-year-old's DBH begins to slow down. However, in the age of 55-74, the tree height of stand has been grown only 5 m during 19 years and the growth rate and curve are getting slow. DBH-H curve has been changed regularly by age. Depending on the influences of insufficient or unequal weighting of data and integrating within DBH-H curves, estimation bias would be made. It has been suggested that when DBH-H curve is used to estimate tree height, we should consider the restrictions of age and range and the reasonable curve shape.

並列關鍵字

tree height ； diameter at breast height ； Taiwania plantation

國際替代計量

溪頭地區臺灣杉人工林不同林齡胸徑與樹高生長之研究

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