The relationship between tree canopy and crime rates across an urban–rural gradient in the greater Baltimore region

A considerable amount of research has aimed at answering the question of whether there is a link between tree canopy cover and crime. This study sought to answer that question for the greater Baltimore region, which covers a wide range of land uses, from dense urban areas to agricultural and rural areas, and which features a wide range of crime rates, with some neighborhoods experiencing almost no crime to others with crime rates many times the national average. Geocoded crime data was used to create a crime index. Tree canopy data came from 2007 1-m resolution color infrared imagery and LiDAR data, which were incorporated into an object-based image analysis tool. Socioeconomic control variables were taken from US Census data. In this study, crime was found to have a strong negative correlation with tree cover, even when socioeconomic variables were controlled for. The results suggest that a 10% increase in tree cover is associated with an 11.8% decrease in crime. The authors caution that it is unlikely that this entire effect is causal but note that the high R-squared values (~84%) suggest there is some genuine relationship between trees and crime.