Street tree health assessment system: a tool for study of urban greenery

Abstract

This study deals with the recording of tree health and the evaluation of the greenery ratio, with a view to increase it, in three representative street trees in Thessaloniki city, North Greece. The three street trees are representative because of the species composition and the health of the trees on one hand and the flow of traffic on the other hand. The three street trees investigated in this study are located along three central roads of Thessaloniki city, namely Nikis Avenue, Egnatia Street and Karamanli Avenue. The study also includes the formulation of proposals in order to make some improvement in the choice of suitable species so as to increase the amount of greenery in the city. The results show that the most important problems related to tree health in the three streets are the leaves being attacked by insects and fungi as well as dry and broken branches of the crown. The majority of trees have moderate health. The greenery ratio in the three street trees is evaluated by the greenery’s surface and volume indicators, which are calculated depending not only on the number of trees but also on the surface and volume of their crowns. Finally, a linear model for the greenery’s volume indicator is estimated which depends on tree height, crown length and crown projection on the ground.