The investigation of pavement trees about their effects on microclimatic adjustments and pedestrians’ perceptions during summer

The improvement of outdoor comfort has received extensive research attention due to extreme summer weather. Trees (an important street landscaping element) have been broadly proven to affect the outdoor environment quality and pedestrian comfort, primarily through canopying and biological effects. These processes affect the light and thermal conditions, influencing subjective comfort levels. This study explores the effects of trees on various climatic indices in the pavements of Qingbaijiang (QBJ), a district of Chengdu, China. Through the analysis of field measurement in nine pavements beside avenues (Jul. 2023), multiple linear regression showed that local residents’ climatic neutral points are 24.52°C (physiologically equivalent temperature (PET)) and 0.952 (illumination, LUX) klx, respectively. Further, tree crown diameter (TCD) plays a significant role in climate adjustment by reducing PET by 8°C (from 40°C to 32°C). In addition, pedestrians had different thermal responses to different species of trees. Finally, Cinnamomum camphora could create a microclimate partially aligned with people’s neutral temperature (around 24°C), although it is hard to achieve a comprehensive comfort improvement relying on trees only. These findings can then direct further the management of urban landscaping and forestry for climate improvements. Urban designers and planners could select tree species that better meet people’s demands during urban construction.