Environmental advocates often wax poetic about the power of trees to create a better world, but the effects of a thick tree cover are usually intangible at best. According to a new study [PDF] published in the June issue of the journal Landscape and Urban Planning, however, there may be a direct correlation between the number of trees in your neighborhood, and how safe you feel there.
The research was a case study of the city of Baltimore, a metropolitan area so riddled with crime, it’s spawned its own cop drama, The Wire. Scientists used high-res satellite imagery to compare crime locations throughout the city with the number of trees in the area. Although we may have a perception that “bad guys” like to hide behind trees and bushes, waiting to jump out and attack us, the study showed just the opposite.
According to the study, a 10 percent increase in trees roughly equaled a 12 percent decrease in crime. “It’s really pretty striking how strong this relationship is,” Austin Troy, director of the University of Vermont’s Transportation Research Center and lead author, told Grist. “When we broke down tree cover by public and private ownership for the spatial model, we found that the inverse relationship continued in both contexts, but the magnitude was 40% greater for public than for private lands,” the authors went on to say.
However, the author’s do acknowledge that “there was a negative relationship between crime and trees in the vast majority of block groups of the study area, there were a few patches where the opposite relationship was true, particularly in a part of Baltimore City where there is an extensive interface between industrial and residential properties. It is possible that in this area a significant proportion of trees is growing in abandoned lands between these two land uses.”
Although it’s only one city, the results from Baltimore are both interesting and encouraging. Trees are the only things on the planet that can absorb carbon dioxide, produce oxygen, clean the soil, prevent erosion and control noise pollution, using only free water and solar energy. These things have a direct impact on our quality of life, but rarely do we acknowledge it. This study, however, draws a statistically significant line between us and trees that can’t be ignored.
Trees do have a positive role to play in our lives, and it’s not just to provide shade or look pretty. Hopefully, this study will help to encourage tree planting in urban areas, and not just in parks or residential areas.