樟樹腐朽現象的案例研究

Abstract

樹木本身有 CODIT 防禦機制，當樹木受傷或腐朽之後，是否採用外科手術來治療處置，首先應該瞭解樹木防禦反應的作用，再決定樹木照護處理的方式。本研究以三株樟樹受到腐朽後的反應作為個案調查，探討正常木材與防禦反應區域的組織構造、物理性質、化學成分之差異，由歸納觀察及科學數據的結果作為範例，首先，色差試驗結果表示樟樹木材反應區內 L*(明度)值低於正常材，顯示腐朽區域外圍的反應區，其木材顏色有變深的情形，而 a*、b*及 C*值皆無明顯差異。Soft x-ray 的樹輪密度圖譜結果，則顯示出反應區的密度較高，其中深色區域最高密度可達1000 kg/m3。在樟樹正常木材及反應區組織切片的觀察中，木材反應區內的薄壁細胞及木質線內有明顯的沉澱物出現，經過染色後的結果，反應區沉澱物為多酚類物質，同時針對木質素染色後的結果，也顯示出木材反應區內木質素含量相對有較高的趨勢。除此之外，反應區部分位置的組織結構明顯與正常木材不同，可觀察到較少的導管，而存在較多的薄壁細胞與木質線的現象。 針對木材反應區化學組成分進行分析，首先，反應區內的灰分含量有較高於正常邊材的趨勢，且以腐朽位置的含量最高。其次，反應區內木質素的含量皆明顯高於正常邊材，而正常木材中，其邊心材之間的木質素含量沒有顯著的差異。腐朽樟樹的反應區及正常木材的全纖維素含量皆有顯著差異，但是趨勢並不一致，需要再進一步探究原因，而沒有腐朽樟樹邊心材之間沒有顯著差異。腐朽樟樹內反應區與正常木材的醇苯抽出物含量，顯示沒有顯著差異；同時，沒有腐朽樟樹邊心材的醇苯抽出物含量，也沒有顯著差異。腐朽樟樹的醇苯抽出物分析結果顯示反應區內的萜類化合物含量都較高，其中 Camphor、 t-Cadinol 及 α-Eudesmol 三項具抗菌效果的化合物，在反應區內所占的面積都較高；而脂肪酸及碳水化合物的含量，則隨著腐朽程度的嚴重或是與腐朽部位的距離愈接近時，其含量有增加的趨勢。綜合上述試驗結果可以瞭解樟樹在受到腐朽後樹木生長反應的防禦機制作用，觀察及判斷防禦反應的現象或自然防禦化學物質，可以作為未來樹木治療照護方法的應用依據。

The tree itself has a CODIT defense mechanism. When the tree is injured or decayed, we should first understand the tree defense response, and then determine whether to use surgical treatment or not. In this study, three decayed Cinnamomum camphora trees’ reaction as a case study to investigate the differences in the structure, physical properties and chemical composition of normal wood and defense reaction areas. First, in the reaction zone wood color got darker as it got closer to the decayed area, and the tree density in the reaction area was obviously higher, moreover, some of the dark area’s density was up to 1000 kg/m3. The results of wood tissue section observations indicated that there were deposits in parenchyma cells and rays within the reaction zone in C. camphora. Further, the section staining results also indicated that the deposits may be polyphenols, at the same time the lignin staining results also showed the relatively high lignin content in the reaction zone. In addition, some structure of the reaction zone is obviously different from that of normal wood, there was fewer vessel can be observed, but a large number of parenchyma cells and rays. According to the composition of the reaction zone, most results showed that the content of ash in the reaction zone was higher than that in healthy sapwood, and the content of decayed sites was the highest. Next, the content of lignin in the sample reaction zone was also obviously higher than that in sapwood while the content between the sapwood and heartwood in the healthy material was not significant. The reaction zone of decaying C. camphora and the total cellulose content of undecayed wood were significantly different, but the trends were inconsistent, so there are further reasons need to be explored, also there was no significant difference between the heartwood and the sapwood of undecayed C. camphora. Last, there was no significant difference in the content of alcohol benzene extracts between the reaction zone and normal wood of decayed C. camphora. At the same time, there was no significant difference in the content of alcohol benzene extracts between the heartwood and the sapwood of undecayed C. camphora. The composition analysis of alcohol-benzene extracts from decayed C. camphora showed that the content of terpenoids in the reaction zone was higher. Among them, Camphor, t-Cadinol and α-Eudesmol that were three antibacterial compounds had a larger area in the reaction zone. However, the fatty acid and carbohydrate content tended to increase while getting closer to the decayed site. Based on the above test results, we can understand the defense mechanism of decayed C. camphora. Observing and determining the phenomenon of defense reaction or natural defense chemicals which can be used as the basis for future treatment methods of tree care.