Key Factors Influencing Street Tree Root Conflicts with Planting Pits and Sidewalks in Old Guangzhou, China

Urban street trees improve urban life quality, but their root systems can conflict with infrastructure, especially in densely populated areas. Guangzhou—one of the world’s most densely populated cities—experiences significant challenges related to street tree root-damage, which impacts urban infrastructure and public safety. This study examined factors affecting root-damage in 1,227 street trees in Guangzhou’s old urban areas, focusing on tree phenotypic parameters, planting environment, and root characteristics. Variables recorded included Tree height (TH), Crown width (CW), Diameter at breast height (DBH), root distribution, presence of buttress roots, and planting pit size. Logistic regression identified key factors influencing root-damage occurrence and severity. Results showed 30.9% of trees exhibited root-damage. Shallow-rooted species such as Ficus microcarpa and Ficus altissima had higher root-damage rates (41% and 47%, respectively). Key predictors included DBH, planting pit size, and buttress roots. DBH was positively correlated with root-damage; larger planting pits reduced root-damage risk; and buttress roots increased root-damage likelihood. Trees with buttress roots were more likely to cause severe damage, and trees with DBH > 40 cm were prone to moderate and severe damage. These findings offer valuable insights for urban planners and forestry managers to optimize tree selection and planting strategies, mitigating root-damage and enhancing urban infrastructure resilience.