Tree choice can help fight crime

trees A recent study undertaken by U.S. Forest Service‘s Pacific Northwest (PNW) and Southern Research Stations took a look at the relationship between crime and trees and found that what type of tree you have in an area could determine the crime rate for the region. The sample of 2,813 homes looked at crime rates between 2005 and 2007. In the sample there were 394 property crimes and 37 violent crimes during the period.

The research was conducted in Portland, Oregon and led by Geoffrey Donovan a research forester with PNW Research Station. ”We wanted to find out whether trees, which provide a range of other benefits, could improve quality of life in Portland by reducing crime, and it was exciting to see that they did,” said Donovan. “Although a burglar alarm may deter criminals, it won’t provide shade on a hot summer day, and it certainly isn’t as nice to look at as a tree.”

We believe that large street trees can reduce crime by signaling to a potential criminal that a neighborhood is better cared for

Donovan and his fellow researcher, Jeffrey Prestemon from the Southern Research Station, got crime figures from the Portland Police Bureau and placed the rimes into one of several categories. They then used details of crimes that could be associated with an actual address. Through the use of site visits, aerial photography and property tax information the researchers were then able to run various mathematical models and statistical analysis on the information. the researchers looked for any impacts that various tree properties had on crime. some of the variables that the scientists looked at included tree canopy size, number of trees, whether an area had street trees or garden trees, in total more than 24 variables were tested against crime rates.

The researchers concluded that canopy size of street and garden trees together with the number of trees in a garden had the greatest impact on crime. Large street and garden trees had lower crime rates while properties that had greater number of smaller trees had the highest crime rates.

“We believe that large street trees can reduce crime by signaling to a potential criminal that a neighborhood is better cared for and, therefore, a criminal is more likely to be caught,” Donovan said. “Large yard trees also were associated with lower crime rates, most likely because they are less view-obstructing than smaller trees.”

In contrast, their analysis indicated that small garden trees might actually increase crime by blocking views and providing cover for criminals—an effect that homeowners can mitigate by keeping trees pruned and carefully choosing the location of new trees.

Urban trees are an important part of the environment – not just visually but also environmentally. They are imports in helping to reduce air pollution in residential areas, provide food and habitat for urban wildlife and can help mitigate rainfall so reducing flooding. they also provide shade and help to keep cities cool so reducing the heat trap that can build up in a very urbanised environment. ensuring that the right trees are planted by urban planners is important not just from a visual aspect but now also from a crime reduction aspect. When new planting is proposed in an residential or urban environment choosing larger trees could be much more beneficial in the long run than opting for quick growing but smaller amenity trees.

This research is also good news as it counters the arguments that some people put forward to remove trees in order to reduce crime. This study shows that when an area have large established trees rather than being a place for criminals to hide behind they actually deter criminals.

poto credit: jaromematthew