Research proves that higher amounts of trees in urban areas give many benefits, from energy conservation to reducing levels of stormwater. But did you know many cities can use trees to fight crime?
Researchers across the United States have examined how trees improve the quality of life for people who live in cities. One of these was seeing how tree cover affects criminal activity, and the results are pretty startling!
Tree Cover And Crime: A Case Study 
The idea that trees can reduce crime isn’t conjecture – there’s a lot of research behind this. Take a recent study out of the city of Baltimore, which found that a 10 per cent increase in trees equalled an approximate 12 per cent decrease in crime. A team of researchers teased apart this relationship between higher amounts of tree canopy and lower rates of lawless activity in and around the city.
Using data from Spotcrime – a website that shows crime incidents on maps – the researchers overlaid high-resolution satellite pictures that showed the extent of tree cover. They controlled for socioeconomic factors like income and the age of housing and adjusted for other variables associated with tree covers like the urban/rural divide and population density. Even when considering these factors, areas with higher amounts of trees showed lower rates of crime. We should note that parts of the city with trees showed evidence of a lower crime rate; areas with low-lying shrubs and brush saw increased rates.
The conclusion might strike some people as a contradiction: like bushes, don’t trees block views of criminal activity? Turns out, not nearly as much, and any obstructions are off-set by how trees get more people outdoors!
People Feel Safe Around Trees!
One theory as to why tree cover can reduce crime is that people enjoy spending more time outside in areas that have large trees. With more people walking the streets, sitting on porches, and 
hanging out in green spaces, there are more eyes around to deter lawless activity. Well-tended trees also signal to would-be criminals that there are people who will watch everything they do – a theory called the “eyes on the street effect”!
Trees give residents a more positive view of their surroundings in other ways, too. More studies have shown that people in public housing feel safer in residences with higher amounts of trees and grass, compared to those living in areas with less vegetation. Large trees on streets show potential culprits that the neighbourhood which they are targetting is better cared for, and as such, any criminal would be more likely to be caught in the act of a crime.
Reduced crime isn’t the only benefit – there are many positives to planting and caring for trees in cities. They act as large natural air filters, removing high amounts of particulate matter, carbon monoxide, sulphur dioxide, nitrogen dioxide, and ozone. Trees in urban spaces can improve air quality by as much as 15 per cent. For such a small investment, trees benefit the community in so many ways!