Trees: Are They Baltimore’s Heroes or Villains?

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Baltimore's tree canopy:  a crime deterrent?
Photo by Lester Spence

Trees, bushes, and other plant life may spruce the city up (pun emphatically intended), but that doesn’t mean they don’t have their enemies. There’s a faction out there arguing that urban greenery aids and abets criminals by providing convenient space for lurking; they point to a 2001 study that found that car thieves preferred areas with dense vegetation. Tall trees are no better — they block illumination from streetlights and make the sidewalk below more sinister. Luckily, these people turn out to be wrong — at least in Baltimore’s case. New research published in the June issue of Landscape and Urban Planning shows that an increase Baltimore’s tree canopy correlates with a decrease in crime. So who’s the bad guy now?

The study looked at rates of both crime and tree canopy all across the region, from the far edges of Baltimore County to the middle of the city. It’s no surprise that places with more trees tend to have fewer crimes, of course — trees and bushes are more common in affluent areas, where crime rates tend to be lower. But even after controlling for income, race, and population density, the link between more trees and less crime was still there.

One caveat:  the trees did occasionally seem to be in cahoots with criminals. In places like Brooklyn Park, where there’s a whole lot of thickly overgrown vegetation, more green space does correlate with more crime. (Or, as the study’s authors put it, “the concealment value of the vegetation outweighs its deterrent effect.”) But in general, “a 10% increase in tree canopy was associated with a roughly 12% decrease in crime.” Good thing the city has plenty of free trees available to be planted by anyone with the space and inclination; just give Parks & People or the Baltimore Orchard Project a call.

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