本研究主要以台大實驗林於1933年於溪頭營林區設置之柳杉長期試驗地資料進行林 木生長及林分結構分析，本試驗地林齡到達第9年時會開始出現自我疏伐現象林木株數逐漸減 少，但因留存木之生長持續，故林分蓄積仍可不斷增加，林齡為25年時蓄積量已達489.29 m3/ ha；此時柳杉之高生長已接近最大值24公尺，然胸徑仍可持續增加，最大可達56公分，故透 過適當之管理溪頭應可生產大徑木之柳杉。

This study was conducted in a long term Japanese cedar plantation established in 1993 in the Xitou Tract of the National Taiwan University Experimental Forest. The main objective was to explore the proper management strategy for Japanese cedar by analyzing tree growth and stand structure. We found that when the stand reached its nine-year-old age, it started self-thinning phenomena and the number of trees within the stand gradually decreased. However, stand stocking kept increasing due to the growth of the trees left on the site. The total stocking reached 489.29 m3/ ha when the stand was 25 year old, and the height growth approached 24 meters height, which is the maximum height growth of Japanese cedar. The breast height diameter growth still increases after 25 years, and approaching its maximum at 56 cm. Therefore, we conclude that we can produce large size Japanese cedar under proper stand management in Xitou.