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Ever get a request to volunteer to plant trees at your favorite park?  Personally, I receive at least a half dozen of these requests a year.  It turns out that there is a good reason parks in Baltimore emphasize tree plantings.  An increase in tree canopy is a sign of lower crime rates in Baltimore neighborhoods.

A paper by Troy, Grove and O’Neil-Dunne from 2012 reported that crime rates are lower in areas in Baltimore where there is more tree cover.  While trees themselves do not actually lower crime, “there is a strong inverse relationship between tree canopy and . . . robbery, burglary, theft and shooting.”[1]  The authors found that such positive results appeared on both private and public land in Baltimore.  In one of their models, they found that “a 10% increase in tree cover would be associated with an 11.8% decrease in crime rate.”  While the authors do not suggest that trees are a cause of lower crime rates, they do find that tree cover is an indicator of a community with lower crime rates than those with less tree cover.  The Troy, Grove and O’Neil-Dunne study is in-line with several studies conducted in other cities as well.[2]

While it’s hyperbole to suggest that “more trees = less crime,” studies do confirm that a well developed tree canopy is a sign of a healthy neighborhood.  In Baltimore, the Troy, Grove and O’Neil-Dunne study further indicates that a robust tree canopy on public land, like parks, has  greater positive results on crime rates than a similar tree canopy on private lands.  For those Baltimore neighborhoods and parks in high-crime areas, planting more trees should be one of the strategies used to help reduce crime rates.  While the trees by themselves will not reduce crime, an increase in tree canopy may be the catalyst for the actual mechanisms that are triggering reduced crime rates.

Baltimore already has the foundation for increasing tree canopy on public lands through TreeBaltimore that works in conjunction with the Recreation and Parks Department’s Forestry Division.  When deciding where to assign the various tree-related resources, focusing tree planting and maintenance in high-crime areas may have added benefit to other crime reduction strategies.

So the next time you get an invitation from your local park group or neighborhood association to plant trees in your local park or neighborhood – join them!  Your efforts may actually be helping to reduce crime rates in the surrounding area.

[1] Austin Troy, J. Morgan Grove & Jarlath O’Neil-Dunne, The relationship between tree canopy and crime rates across an urban-rural gradient in the greater Baltimore region, Landscape and Urban Planning 106 (2012) 262-270, https://www.nrs.fs.fed.us/pubs/jrnl/2012/nrs_2012_troy_001.pdf

[2] Tania Schusler, Leah Weiss, Davin Treering, Earvin Balderama, Research Note: Examining the association between tree canopy, parks and crime in Chicago, Landscape and Urban Planning 170 (2018) 209-313 https://www.researchgate.net/publication/318771547_Research_note_Examining_the_association_between_tree_canopy_parks_and_crime_in_Chicago; Andrew W. Eckerson, Understanding the relationship between tree canopy and crime in Minneapolis Minnesota using geographically weighted regression, Papers in Resource Analysis, 15 (2013) vol. 15 (showing , http://www.gis.smumn.edu/GradProjects/EckersonA.pdf; Geoffrey H. Donovan, Jeffrey P. Prestemon, The Effect of Trees on Crime in Portland Oregon, Environment and Behavior 44 (2012) 3-30, https://www.fs.fed.us/pnw/ruwit/papers/donovan/TheEffectofTreesonCrime.pdf.

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