05/30/2008 10:31 am ET Updated Nov 17, 2011

What One Tree Can Do For ADD, Crime And Stress

If a tree grows in a city and nobody is there to assess its ancillary benefits to society, is it worth anything?

We can all agree that green, living things like trees, wet lands, green spaces, even flowers, help deal with costly problems like cleaning the air, reducing urban heat island effect, reducing storm-water runoff...and besides, they're pretty!

What folks might not know is that studies from the University of Illinois Landscape and Human Health Laboratory document the positive effects they have on people who see them regularly. They help deal with other costly problems by reducing Attention Deficit Disorder, crime levels, stress in kids and adults, and they increase community pride.

Happy people with good self-esteem generally don't skip school, abuse drugs or alcohol, beat their spouses or commit other crimes. It turns out that people living in areas without trees and other greenery have dramatically higher rates of these and other problems. Trees don't make these problems go away, but they are a piece of the puzzle, and they do play an important role.

So next time you see a tree, don't be corny and hug it, but show your gratitude by making it's life a little easier: if you see any trash around it, pick it up, water it if it hasn't rained for a while, and don't let your dog do its business near it. While you're at it, give it a mental thank you. Okay, maybe that's a little corny, but it's doing a great big job.