Risk assessment of street trees failure by non-experts: a case study from the North of Israel

Street trees are valuable to urban environments, providing environmental, aesthetic, and social benefits. However, local authorities and municipalities are under pressure to cut down street trees because of concerns about fallen trees and broken branches. The problem is that this risk assessment can be done only by agronomists (experts) in some places, which is limiting. The idea is to train the local municipality's gardeners (non-experts) to conduct risk assessments for street trees using a criteria-defined protocol developed by the Israeli Ministry of Agriculture. In our case study, we compare a risk assessment on street trees done by gardeners to a risk assessment done by an agronomist. The findings showed that most non-experts agreed with every criterion in the protocol. The strength of the relationship between the expert score and the non-experts' average score was high and significant. Most criteria had a high or complete agreement between the gardeners and the agronomist. The visible risks criterion has a medium agreement, while the height-diameter ratio criterion has the lowest agreement between the gardeners and the agronomist. Local authorities and municipalities have room to rely on their gardeners (after a short training) to assess the risks of street trees falling when a criterion-defining assessment protocol is used.