Last month, Brian wrote about how to spot income equality from space -- all you need to do is look for the trees. According to a new study, trees are more than a marker of neighborhood wealth: They reduce crime as well, at least in Baltimore.
Austin Troy and Jarlath O'Neill-Dunne of the University of Vermont and J.Morgan Grove of the USDA Forest Service looked at the relationship between urban tree cover and rates of robbery, burglary, theft and shooting (controlling for the wealth disparity Brian's post concerned). They found that a 10 percent increase in tree canopy corresponded to a roughly 12 percent decrease in crime, in Baltimore City and County.
The study, "The relationship between tree canopy and crime rates across an urban–rural gradient in the greater Baltimore region," was published last week in the journal Landscape and Urban Planning. The findings validate the results of a 2010 study that suggested that the presence of large trees matched a lower rate of criminal activity. Geoffrey Donovan, one of the researchers on that study, speculated:
We believe that large street trees can reduce crime by signaling to a potential criminal that a neighborhood is better cared for and, therefore, a criminal is more likely to be caught.
The authors of the Baltimore study don't offer any guesses as to why more trees means less crime, but they do note that "tree planting prioritizations should incorporate public safety concerns." Or as Grist puts it, it's time "the police become a bit more hands-on in urban landscape planning and green thumbing."
If you buy the argument that reducing urban crime rates is a key to a sustainable future, trees can make our cities safe, green, and the best hope for an environmentally-sound future.