執行成果摘要
The purpose of this study was to investigate the dangerous degree of tree for suggestion of tree amnagement. The tree hazardous items and their wood physical properties were explored by visual tree assessment and detected by nondestructive techniques. There were providing service of tree risk assessment and tree management suggestions. A total of 18 tree species and 205 trees from field test. There were seven tree hazadous items, i.e. decayed wood, cracks, tree root problem, weak branch unions, cankers, poor tree architecture, and dead trees, tops, or branches etc for referenced visual investigation. When the transversal stress wave velocity was ＜ 1000 m/sec, or ＜ 70% of acoustic velocity, or drop 20% drilling resistance value of sound or non-decayed tree could be applied for decayed or hole wood level in tree hazard assessment. The tree risk management program planning was made by the references and statistic method for providing information.