Many people fear approaching densely vegetated areas around urban parks or in parking lots at night, or share a perception that trees and shrubs might give criminals a hiding spot.
Kuo and Sullivan (2001) examined evidence from past research and a study of an inner-city apartment complex. Residential trees and shrubs were linked to lower levels of crime, even when controlling for other factors that explain crime. Later studies have confirmed this result (Snelgrove et al. 2004; Branas et al. 2011). Kuo and Sullivan propose two possible reasons for this based on past research:
- well-maintained trees and shrubs in residential areas indicate to potential criminals that the homeowner cares about and pays attention to his or her surroundings, and thus may notice and report suspicious behavior, and
- vegetation around the home reduces mental fatigue, and therefore reduces irritability and anger.
Crime Prevention Through Environmental Design (CPTED) is an area of research expanding on the idea of using architect and landscaping designs to deter or prevent criminal behavior. In any case, to the extent that criminals might hide behind dense vegetation, homeowners can reduce this risk by managing trees and shrubs to maintain visibility.