Big trees fight crime, and other wonders

Enlarge Image

(WINNIPEG FREE PRESS ARCHIVES)

Winnipeggers may not realize this, but their city is home to a number of unique record-holding collections. The biggest Ukrainian-language book collection outside Ukraine is housed in the city's Oseredok Cultural Centre. The Winnipeg Art Gallery possesses the most extensive collection of Inuit art in the world. Finally, the River City boasts the largest number of publicly owned elm trees on the planet.

Most citizens probably appreciate the esthetic value of these trees, and studies show they are useful for sequestering carbon and improving air quality by as much as 15 per cent. The shade they provide also reduces energy demand, while tree canopies absorb large amounts of rain in both their leaves and roots, assisting with stormwater management.

Yet, in recent years, North American urban planners have begun to realize the value of large trees (growing more than 4.5 metres) extends well beyond ecology. In fact, these green giants offer a number of rather surprising, but impressive, social benefits.

Firstly, trees improve traffic safety by providing a distinct edge to sidewalks and shielding pedestrians from out-of-control cars. Research has also found drivers are more likely to slow down along a treed street than a bare one, which reduces the chance of accidents.

Interestingly, however, motorists actually perceive the time it takes to travel through a treed neighbourhood as shorter than the time it takes to drive the same distance in a treeless area, which helps reduce their stress levels.

Additionally, trees create more pleasant walking environments -- think Corydon Avenue in the summer -- that lead to increased pedestrianism and engender a sense of pride and care for a neighbourhood. It is, therefore, not surprising that researchers at the University of Montana discovered businesses along tree-scaped streets enjoy 20 per cent higher revenue streams than shops operating in treeless communities.

While it is more difficult to put a dollar figure on some of the other ways trees improve the well-being of a city's residents, hospital patients who enjoy a view of trees out their window have been found to recover more quickly than patients who do not (cutting health-care costs), while employees who can see trees and other greenery from their offices report being happier at work, increasing productivity.

Perhaps most surprising, trees have even been shown to reduce criminal activity. A major study carried out in 2010 by the U.S. Forest Service in Portland, Ore., found homes surrounded by large trees had lower crime rates.

A similar study undertaken in Baltimore, Md., earlier this year discovered a 10 per cent increase in tree cover led to a roughly 12 per cent decrease in crime -- even after controlling for variables such as the wealth of the neighbourhood.

The researchers could only speculate as to why this is, but suggest large trees make a home seem more cared-for, and hence its residents more vigilant; small bushes, in contrast, provide a place for criminals to hide.

Unfortunately, many North American cities no longer enjoy a lush forest cover, as over the last few decades developers chose smaller, more ornamental species over the large trees that bring the vibrancy and advantages described above.

Winnipeg is fortunate that many of its neighbourhoods can still boast an elm-tree canopy, but there is cause for concern here as well.

In 1975, Winnipeg had 275,000 elm trees, but since then the number has dropped to just 140,000. Last week, the city warned Dutch elm disease and old age are taking their toll on these remaining leafy assets -- valued at over $800 million -- meaning Winnipeg could eventually lose its elms.

At a time when other cities are looking to increase their tree stock, Winnipeg should take steps to ensure the continued health of its own green canopy. The city and province can take the lead by providing adequate funding for tree protection and replacement, but even citizens can help.

Properly watering trees on private property is one of the simplest things homeowners can do. As well, they can -- logically -- plant more trees. Not only good for the city more broadly, increasing the number of trees around homes actually makes sense financially: They provide shade that reduces air-conditioning bills for property owners, and evidence shows land values increase when well-maintained green assets are present. Because with so many public and private benefits, when it comes to protecting its urban forest, Winnipeg should do all it can to "leaf" no tree behind.

Benjamin Gillies is a political economy graduate from the University of Manitoba, where he focused on urban development and energy policy. He works as a consultant in Winnipeg.

Republished from the Winnipeg Free Press print edition November 28, 2012 A12