Who knew that trees were such responsible citizens?

By expanding the urban forest by some 20 percent to cover more than one - third of the city, leaders hope to reap a range of benefits, including... increased psychological well-being among residents.

Increased psychological well-being? That's something I haven't heard of before. I looked into it on Google and found:

The conventional wisdom has been that trees and other vegetation have a negative impact on crime because they provide cover for criminals and reduce opportunities for casual surveillance.

Research in a particularly deprived area of inner city Chicago has suggested that this is in fact not the case and that appropriate vegetation cover can lead to reduced crime rates (Kuo and Sullivan, 2001(a)). The study dealt largely with mown grass and high canopy trees, which do not provide cover in the same way as, for example, shrub planting. It looked at an area with relatively homogenous architecture and a relatively homogenous population but with differing levels of vegetation. Areas with higher vegetation cover were found to have lower rates of crime, as measured by reports to the police.

Crime-fighting trees? That's interesting. There's even a website that helps people reduce crime by strategic landscaping. What's more, the International Herald Tribune sources the U.S. Department of Agriculture's Forest Service to say, "for every dollar invested in planting one, there's a more than $5 return" in property value, air quality, storm water management, energy savings, and carbon dioxide removal.

City greening projects seem to abound: in Boston, New York City, Kansas City, and Toronto, to name the few examples I could find. The US Forestry Service has developed a new tool to determine how many trees there are in a given city, giving rise to an "urban tree canopy cover" percentage (Boston's is 29%, New York City 24%, Baltimore 20%, Annapolis 41%).

Of course, you can't just go planting trees willy-nilly. You have to consider biodiversity, how the trees are planted, proper care, etc. Boston hired arborists to help them.

With so many benefits and such a high rate of return, I hope other cities take a look into this.