A Tree Grows in Portland: the relationship between trees and crime

Geoffrey Donovan and Jeffrey Prestemon, "The Effect of Trees on Crime in Portland, Oregon," Environment and Behavior 44 (2012): 1

The take-away: Regarding data from Portland, Oregon, this study identifies a number of associations between, first, the presence of different kinds of trees, and second, the occurrence of different kinds of crime. It is concluded that small trees are associated with increased crime, whereas larger trees are associated with reduced crime. 

Abstract

The authors estimate the relationship between trees and three crime aggregates (all crime, violent crime, and property crime) and two individual crimes (burglary and vandalism) in Portland, Oregon. During the study period (2005-2007), 431 crimes were reported at the 2,813 single- family homes in our sample. In general, the authors find that trees in the public right of way are associated with lower crime rates. The relationship between crime and trees on a house’s lot is mixed. Smaller, view-obstructing trees are associated with increased crime, whereas larger trees are associated with reduced crime. The authors speculate that trees may reduce crime by signaling to potential criminals that a house is better cared for and, therefore, subject to more effective authority than a comparable house with fewer trees. 

Full article (free public access via the U.S. Forest Service)