阿里山紅檜神木的樹齡評估及木材強度之變異性研究

ALISHAN VETERAN RED CYPRESS ANALYZED TREE RING AND TESTED VARITY OF WOOD STRENGTH IN TAIWAN

詹明勳(Ming-Hsun Chan) ； 黃晨光(Chen-Guang Huang)

《中華林學季刊》 48卷3期 (2015/09) Pp. 263-281

摘要

阿里山神木紅檜(Chamaecyparis formosensis)，1956年遭雷擊後死亡，1998年因安全考量放倒原生育地存放，分成2塊根株及3塊幹材。阿里山神木為該地區代表性森林地景紀念物，富有歷史文化價值，應予以適當保存與展示，因此擬將保存神木幹材作為裝置藝術，提供觀光資源吸引遊客。樹芯取樣從放倒3塊幹材(T1=16.3 m、T2、T3=16.8 m)，以生長錐每公尺鑽取1-2支樹芯(T1=32支、T2=22支與T3=16支)，合計共70支樹芯。樹輪分析以T1的16根樹芯先進行目視交互定年，再進一步做交互定年比對出一致性顯著的樹芯，組合成主年表進行迴歸分析樹齡，提供解說的材料。木材性質以3塊幹材54支樹芯，使用微破壞儀檢測木材抗彎強度(bending)及抗壓強度(compression)，提供施工參考。交互定年GLK值達顯著一致性的11支樹芯，合併為411年之主年表。年表每公分年輪數為11.5年，胸高直徑466 cm，估算樹齡為2,680年。平均輪寬為0.87±0.05 mm yr^(-1)，估算樹齡最大值為2,841年；最小值為2,533年。以主年表累積輪寬及樹齡建立直線迴歸模式，估算樹齡為2,904 年。木材平均含水率為74.64%，平均生材密度為1,050 kg m-3狀況下，總材積19.47 m^3，總質量19,314±652.12 kg，平均抗彎強度為485.3±24.5 kgf cm^(-2)，平均抗壓強度270.3±16.1 kgf cm^(-2)。氣乾(FSP)材抗壓強度比含水材強，且有顯著差異；抗彎強度則無顯著差異。

關鍵字

微破壞儀 ； 阿里山神木 ； 樹輪分析 ； 木材性質

並列摘要

The Veteran Red Cypress of Alishan (Chamaecyparis formosensis) was struck and dead by lightning in 1956. Due to the security consideration, it was fell on the original site in 1998, then was divided into 2 stump roots and 3 partial trunks. It was a red cypress stands landscape monument of local area and was rich in historical cultural value which should be preserved and exhibited adequatly. Therefore, we intended to conserve it as an installation art for providing tourism attraction. Sampling cores from 3 trunks (T1=16.3 m, T2, T3=16.8 m) by using increment borer and 1-2 sample cores per meter (T1=32, T2=22 and T3=16), achieved 70 cores samples. Taking 16 tree cores of T1 to analyzing the tree rings using visual crossdating methodology. Further on cross-dating we tried to find the high synchronization coresby combining a master chronology and using linear regression model to provide instruction material which could used to estimate tree age. In order to gain wood characters from these 3 trunks that have 54 core samples, we used Fractometer II instrument to test bending and compression strength that could provide engineering reference. On cross-dating GLK test had significant synchronization from chosen 11 cores which were able to combine a master chronology that had 411 yr. Tree ring width per centimeter 11.5 yr and diameter at breast height was 466 cm, which estimated thetree age would be 2,680 yr. Mean ring width 0.87±0.05 mm with its estimated maximum age would be 2,841yr and minimum 2,533 yr. Linear regression model estimated tree age by accumulating the ring widths and tree age form the master chronology was 2,904 yr. Under the circumstance that mean density in green condition was 74.64% , mean density in green condition was 1,050 kg m^(-3), the total volume trunk was 19.47 m^3, the total weight was 19,314±652.12 kg, mean wood bending strength was 485.3±24.5 kgf cm^(-2), and the mean compression strength was 270.3±16.1 kgf cm^(-2). Compression strength in Fiber saturation point condition was significantly stronger than watery wood; however, bending strength was no significance.

並列關鍵字

Fractometer II ； alishan veteran of red cypress ； tree ring analyzing ； characters of wood