A recent article in Landscape and Urban Planning found that a 10-percent increase in tree canopy in Baltimore was correlated with a 12-percent decrease in robbery, burglary, theft and shootings. Maintaining healthy trees in neighborhoods appears to have a similar effect on reducing crime rates as replacing broken windows and other maintenance on abandoned buildings in crime-prone areas of a city.
To learn more: http://www.txchnologist.com/2012/walkable-green-neighborhoods-key-to-safer-future-cities