The assessment of hazardous oriental plane (Platanus orientalis Linn.) trees in Valiasr street of Tehran

Street trees are one of the most important components of urban green spaces. Any defects in street trees may cause injuries to human, vehicles and buildings. In this research, the assessment of hazardous oriental plane (Platanus orientalis L.) trees was carried out on both sides ofValiasr street (between Tajrish square toTous street cross section). Eight types of tree defects were detected: dead woods, cracks or seams, weak branch unions, decay, wound or cankers, root problems, poor tree structure and contact with power transmission lines. Totally, 457 trees were sampled. The results showed that the dead woods and poor tree structure are the main tree defects (with values of 80 and 69 percent of all sample trees, respectively), while weak branch unions and decay have less importance. Regarding to combination of tree defects, 19 trees were classified as very dangerous and must be removed. Furthermore, trees in medium and high risk classes were classified based on their potential to move toward more dangerous classes. Totally, improvement practices such as pruning of dead branches of trees with medium and high risk and cutting of very dangerous trees are recommended.