Street trees and crime: What characteristics of trees and streetscapes matter

Abstract

The extent to which street trees affect crime is moderated by many characteristics of tree structure, streetscapes, and tree management. To effectively utilize urban greening interventions as crime preventing programs, it is necessary to distinguish tree-related characteristics that increase crime from those that cause crime to decline. This study derived a complete set of tree-related characteristics and crime attributes from a variety of sources. We then applied ordinary least squares and spatial Durbin regressions to reveal the associations between street trees and crime in New York City. Our results showed that street tree characteristics that were negatively associated with crime rates included tree canopy cover, species diversity, and streetscape greenery, while the opposite was observed for the proportion of small-sized trees. The characteristics of street trees that displayed a dual-feature with crime rates included tree health, proportion of harmful tree guards, and proportion of trees with trunk problems, while tree stewardship was not significantly associated with crime. In addition, our findings demonstrated that tree canopy cover and streetscape greenery were conducive to reduce crime severity. The mixed associations between street tree characteristics and crime could be potentially explained by the “broken window theory”, trees’ view-obstructing effect, the “eyes on the street”, and trees’ therapeutic effect. The revealed findings have important implications for the implementation of tree-planting programs in tackling the dual tasks of improving urban greening and reducing crime, and could help translate crime reduction into specific actions of streetscape design and tree management that can be taken by government and local stakeholders.