應用目視樹木評估法診斷台南地區老樹危險度

Damage Evaluation of Aged Trees in Tainan Area using Visual Tree Assessment

詹明勳(Ming-Hsun Chan) ； 洪上立(Shang-Li Hung) ； 蔡明哲(Ming-Jer Tsai) ； 陳勁豪(Jin-Hau Chen)

《中華林學季刊》 44卷4期 (2011/12) Pp. 517-538

https://doi.org/10.30064/QJCF.201112.0004

摘要

老樹是大自然給與我們最珍貴的文化資產，樹木如同人類一樣面對衰老病死的一面，受到大自然干擾如颱風、病蟲害、地震、火災；人類的影響如不當修剪、生育環境鋪面水泥化、道路拓寬、不當移植等種種因素，使得樹木生長形態上產生了結構上的變化，因而造成樹木結構安全上的顧慮，因此建立有效的樹木健康安全評估方法是當前重大的課題。本研究以台南地區老樹為對象，從台南縣政府列管保護的老樹選取18株，另由麻豆鎮總爺糖廠園區內選取非榕樹類DBH達60 cm以上者12株，合計共30株。30株老樹計有芒果8株、榕樹6株、樟樹3株、黑板樹2株、茄苳2株、龍眼2株、欖仁2株、麻六甲合歡2株、蓮霧2株及刺桐1株，先以目視樹木評估法（VTA）先進行外觀評估，項目包括樹木活力、主幹上的大枝條、樹幹、幹基根部並配合美國林務署樹冠健康監測調查方法之樹冠指標等級判定其健全度，再依判定結果將不健全需應用儀器精密檢測之老樹，以超音波、應力波、鑽孔抵抗儀及微破壞儀等儀器進行檢測。結果顯示健康狀態良好6株（20%），需要觀察14株（47%），需要長期觀察6株（20%），不健全需要儀器精密檢查4株（13%）；經比較目視樹木評估法老樹健康指標分數與樹冠混合指標之樹冠生產效率（r=0.33, p=0.02）有正相關性。不健全之老樹其樹幹內部皆有部分之腐朽或空洞存在，經儀器精密檢測分析，目前尚未達到傾倒或折斷之危險程度。本研究應用目視樹木評估法與樹冠混合指標評估法，提供樹木管理單位人員一套簡單可行之監測評估方法，對於老樹或行道樹健康管理得到有用的資訊及早期健康預警，以降低重要文物及生命財產損失。

關鍵字

目視樹木評估法 ； 老樹危險度評估 ； 老樹健康度監測 ； 樹冠混合指標

並列摘要

Aged trees are the most precious cultural assets that nature gives us, they have to confront aging, sickness, and death as well as human beings did, disturbing by typhoon, blight and pests, earthquake, conflagration from nature environment. The influences of human such as improper pruning, paved cement in breeding environment, broaden of roads, inadequate transplant and so on, it causes the structural changes of trees' growing form, and it leads to the concern on tree structure safety. Therefore, established an available method to evaluate the health and the safety of the trees is a challenge to be dealt with lately. This study takes the trees in Tainan area as study objects. We selected 18 trees which are all managed to be protected by Tainan County. On the other hand, we selected 12 non-banyan type trees from Zong-Ye sugar factory in Ma-Dou town, which their DBH rate are all reached at least 60 cm. There are 30 trees in sum. The thirty trees including eight mangos, six banyans, three camphor trees, two green maple trees, two bishop wood trees, two longan trees, two Indian almond trees, two white albizia trees, two wax apple trees, and an India coral tree. First evaluated the outlook of the trees with Visual Tree Assessment (VTA), the items of VTA included the vigor of trees, branches, stem and roots. Then use the Crown-Condition Classification to match up analysis. According to the surface assessment, then selected the poor healthy trees applied to Ultrasonic, Stress Wave, Drill Resistography and Fractometer to examine. The result shows that six trees are in good condition (20%), fourteen trees (47%) needed to be observed, six trees (20%) needed to be observed in longterm, and four trees needed to be checked by nondestructive instruments. VTA and the crown manufacturing efficiency of the composite crown indicators are positive relationship. There are some decayed portions or hole in the trunk of unhealthy aged trees. But, they are not to topple or fracture degree by nondestructive instruments test. Shown by the result of study, it is a feasible method for using surface assessment and instrument to monitor the aged trees. It can provide useful information and heath warning systems for manager of aged trees.

並列關鍵字

Visual tree assessment ； Damage evaluation of aged trees ； Health monitor of aged trees ； Composite crown indicators