臺東縣受保護樹木及準受保護樹木之健康與風險評估

受保護樹木意指具地方代表性、有美學欣賞價值或是和當地居民之生活、歷史、人文研究有連結性的樹木，而透過法令規範使樹木獲得適當妥善之照護。本研究針對臺東縣14個鄉鎮市之受保護樹木及符合受保護樹木標準之樹木進行調查，並利用目視評估法針對樹冠枯梢、樹冠密度、活冠層比、冠層狀態、根部狀態、外部腐朽及植穴大小7項因子進行調查樹木之樹木健康指標評估及風險評估調查。結果顯示臺東縣受保護樹木及準受保護樹木計有39種共337株，以茄苳佔83株最多，其次為苦楝32株、樟樹31株、龍柏30株等。利用因素分析結果顯示臺東縣之受保護樹木及準受保護樹木屬於很健康等級之樹木有14株(4%)、健康153株(46%)、產生劣化163株(48%)、不健康5株(1%)及死亡2株(1%)，而屬高風險之樹木共有13株(4%)，中度風險244株(73%)，低風險之樹木71株(21%)，輕微風險則計有7株(2%)，以植穴過小且生育地周遭被水泥覆蓋之情形是導致樹木高風險的主要原因。

關鍵字

受保護樹木；樹木健康；樹木風險；目視評估法

並列摘要

Protected trees are representative trees in the specific local areas, possessing aesthetic appreciation, and connected with the life, history and humanities of the residents within. Under the related laws and regulations, protected trees are taken care of properly. In this study, the protected trees and pre-protected trees in 14 townships and cities in Taitung County were investigated and the visual tree assessment method was used to assess the tree health by 7 assessment indicators, including crown dieback, crown density, live crown ratio, root situation, external decay, and planting hole size, to survey the tree health index assessment and the risk assessment. The results showed that a total of 337 individuals of 39 species were recorded, and among them, 83 ‎Bischofia javanica individuals accounted for the largest proportion, followed by 32 Melia azedarach, 31 Cinnamomum camphora, and 30 Juniperus chinensis var. kaizuka. The factor analysis results showed that, in Taitung County, there were 14 individuals (4%) classified as “very healthy,” 153 individuals (46%) as “healthy,” 163 individuals as “inferior” (48%), 5 individuals (1%) as “unhealthy,” and 2 individuals (1%) as “deadly.” The number of trees in risk within each level was 13 (4%) for high-risk trees, 244 (73%) for moderate-risk, 71 (21%) for low-risk, and 7 (2%) for trifling. The planting hole too small and the surrounding area covered with cement were the main reason for the high risk to the trees.