RODALE NEWS, EMMAUS, PA—The benefits of trees are as numerous as the acorns falling from a grand oak tree—they help keep our climate in check, reduce flooding, cut energy bills by providing shade, and act as the most eye-appealing air filters on earth. A recent study found trees clean up pollution from volatile organic compounds even better than scientists realized. And not only do they keep us healthy and help us save money, but the right type of tree may keep you safer at home, too, according to a new study in the journal Environment & Behavior.
"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," says lead study author Geoffrey Donovan, PhD, an economist with the USDA Forest Service. "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."
THE DETAILS: Researchers combed through Portland crime data ranging from 2005 to 2007, and then accessed homes involved with crimes to learn about the types of trees on the property. Looking at the tree landscaping of about 2,800 single-family homes through on-site visits, aerial photos, and tax records, researchers found that 394 property crimes and 37 violent crimes took place at these addresses. The rate of protection from crime depended on the size of the tree. For example, the data showed that adding a tree with a 2,000 square foot canopy would result in 10 fewer crimes per 1,000 homes.
"A green strip [of trees] between the sidewalk and the road was always associated with lower crime," explains Donovan. "It's a straight result."
Looking at trees planted near the home, the results were a little different. Large trees seemed to cut back on crime rates. However, smaller trees close to the home actually significantly increased the risk of a crime. Donovan says smaller trees may provide cover for criminals and obstruct homeowners' views out their windows. He found that the crown of taller trees was above a homeowner's line of sight, so they could keep an eye on their yard more effectively. Plus, Donovan says criminals may associate larger trees with a greater likelihood of getting caught because the trees might imply a well-kept community with a strong police force.
Don't worry if you have a smaller tree in your yard, though. Other factors, such as an outdoor light (try a motion light to save on energy costs) can deter criminals, too.