The influence of urban roadside trees and their physical environment on stress relief measures: A field experiment in Shanghai

In recent years, the worldwide accelerated rate of urbanization has highlighted the critical necessity of creating more green spaces for the leisure and recreation activities of urban residents. Nevertheless, the human psychological responses to urban roadside trees with different vegetation have not been fully explored. This study investigates the psychological states (mood, anxiety, restorative outcomes and subjective vitality) after short walks along different urban roads. Three-hundred and sixty-four participants visited four types of urban road: a road where buildings are concentrated was selected as a control road, and three roads surrounded by Sakura, London plane, and Metasequoia trees respectively. The Profile of Mood States, State-Trait Anxiety Inventory, Restorative Outcomes, and Subjective Vitality Scales were used to determine the participants' psychological responses. The physiologically equivalent temperature was utilized to assess the thermal comfort conditions of the selected roads. The results reveal that a short walk along urban roads surrounded by Metasequoia or Sakura or London plane trees respectively significantly reduced the negative psychological states of tension, fatigue, confusion, and anxiety compared to the control road. Additionally, the participants' restorative outcome and vitality were higher after walking along the Metasequoia and Sakura roads. Moreover, no significant differences in the psychological responses to the different roads were detected between male and female participants. Thermal adaptation and psychological parameters strongly affect human thermal comfort levels in outdoor spaces. Our results offer essential insights on the use of urban roadside trees as a resource for mitigating stress and promoting health in urban dwellers.