The detection of wood decay of trees collection Agathis borneensis and Castanopsis argentea at the public area in Cibodas Botanical Garden

Abstract

Due to tree hazard risk, the collection of living plant species in the public area of Cibodas Botanical Garden should be detected. The objective of this research was to assess the existence of wood decay in the stand of Agathis borneensis and Castanopsis argentea tree using visual investigation and Arborsonic measurement technology. Six A. borneensis (20 to 36 m tall) and three C. argentea (16 to 26 m tall) trees were evaluated visually and measured for percentage of decay area. Visual report of A. borneensis indicated that 17% of the root, root collar and crown collar were in damaged and decayed condition; 33% trunk was in damaged and cracked condition; and 83% crown was in dry to damaged limb condition. Visual evaluation of C. argentea showed that the trunk, crown collar and crown were in poor condition. The ArborSonic 3D ® measurement indicated a decayed area ranging from 0-10% and 39-71% for A. borneensis and C. argentea respectively. Only one C. argentea tree indicated a high risk from tree fallen. The others showed a low risk although visually were reported in poor condition. It was caused by Arborsonic risk rating resulted from the percentage decayed area and the safety factor not including the health condition of the tree. Moreover, more attention is required to prevent tree's falling hazard from living plant species of Cibodas Botanical Garden.