本研究旨在探討溪頭地區不同齡級柳杉y'apom'caj人工林樹高的最大 值和林分樹冠受損的情形，並預測不同齡級下的林分樹冠受損率。調查資料來自於13個不 同齡級的林分，進行每木調查，並記錄林木樹冠的受損情形。利用倒數型方程式與不連續 的分段異速生長方程式，作為樹高曲線，估測與預測林木的最大樹高與林分的樹冠受損 率。結果顯示：各齡級林分樹冠受損率在0 °%至46.7°%之間，林分樹冠損害率與林齡無顯著 性相關，將各齡級林木分成上、中及下三層後檢定林分樹冠受損的差異性，發現不同層級 間的樹冠受損率具顯著性差異，上層木有較高的受損率，但不同齡級的樹冠受損數與冠層 層級無顯著性關係。此外，61、81、85及97年生的林分最大樹高預測值分別為26.4 m、27.9 m、29.0m及31.7 m，其林分樹冠受損率為29.51 %、27.54 %、24.36 %及4.96 %。本研究的結 果對於溪頭地區柳杉人工林的生長狀況有更進一步的了解，能提供未來林分樹冠受損評估 的參考依據。

This study aims to predict maximum tree height and crown-damaged trees ratio across 13 age classes in Japanese cedar (Cryptomeria japonica) plantations at Xitou. The expanded allometric equation and discontinuous piecewise allometric equation were used to predict the maximum tree height and crown-damaged trees ratio. The results showed that 0 %-46.7 % of total stands were damaged, and the percentage of damaged trees was not correlated with age in this study. However, crown-damaged trees ratio was significantly different among three crown classes. This pattern was nearly independent of stand age. In addition, maximum tree height of four age classes (61, 81, 85, 97) were predicted at 26.4 m, 27.9 m, 29.0 m, and 31.7 m, and crowndamaged trees ratio were 29.51 %, 27.54 %, 24.36 %, and 4.96 %, respectively. The results of this study provided a better understanding of crown-damaged trees at Xitou.