Alliance for Community Trees News

Can Trees Help Decrease Urban Violence?

By Conni Kunzler | August 18, 2017

Source: Kondo, Michelle C.; South, Eugenia C.; Branas, Charles C.; Richmond, Therese S.; Wiebe, Douglas J. “The association between urban tree cover and gun assault: A case-control and case-crossover study,” American Journal of Epidemiology

Philadelphia, PA (August 3, 2017) – Green space and vegetation may play a protective role against urban violence. U.S. Forest Service researchers investigated the relationships between being near urban tree cover during outdoor activities and experiencing gun violence. Here’s what they found.

The authors conducted geographic information systems–assisted interviews with males aged 10–24 years in Philadelphia, PA, including 135 patients who had been shot with a firearm and 274 community controls, during 2008–2011.

They used statistical analyses to compare tree locations with gun assaults. Each subject reported a step-by-step mapped account of where and with whom they traveled over a full day from waking until being assaulted or going to bed. Geocoded path points were overlaid on mapped layers representing tree locations and place-specific characteristics. Conditional logistic regressions were used to compare case subjects versus controls (case-control) and case subjects at the time of injury versus times earlier that day (case-crossover).

They found that, when participants were under tree cover, they were less likely to experience gun violence. When comparing cases at the time of assault to controls matched at the same time of day, being under tree cover was inversely associated with gunshot assault (odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.55, 0.88), especially in low-income areas (OR = 0.69, 95% CI: 0.54, 0.87). Case-crossovermodels confirmed this inverse association overall (OR = 0.55, 95% CI: 0.34, 0.89) and in low-income areas (OR = 0.54, 95% CI: 0.33, 0.88).

Numerous analyses and comparative models confirmed that being under tree cover was inversely associated with gunshot assault, especially in low-income areas. The authors suggest that increases in urban greening and tree cover in low-income areas be explored as proactive strategies to decrease urban violence.

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