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It’s official: Trees are GOOD for you!

Those of us who enjoy the outdoors have always known that being around trees somehow makes us feel better. The sound of the rustling leaves, the sight of the dappled sun light filtering through the gently swaying branches. The cooling shade from the summer’s heat...


One of the major issues confronting environmentalists (and thus, all of us) is a phenomenon known as Urban Heat Island Effect. We’ll call it UHIE to save space.

What is UHIE? In a nutshell, the air in urban areas can be 6 to 8 degrees warmer than in surrounding rural and suburban areas, particularly in the summer. Apart from being uncomfortable, UHIE increases pollution, reduces air quality and increases energy use (and cost) as we crank up the air conditioning as a counter-measure. So UHIE is bad for the environment, bad for our health and bad for our pocket book.

But there is some good news. This is one of those rare problems where we can all make a change for the better. Not just for the world at large, but also for the little piece of the world that we call home!

Causes of the Heat Island Effect include dark surfaces – that absorb heat from the sun – and a lack of sufficient vegetation.

Traditionally, roofing and pavement tend to be constructed of dark materials (think “blacktop”). An online report by the Heat Island Group suggests that cities would save enormous sums of money by changing what’s known as “roof reflectivity.” How much? Los Angeles would see a net energy saving of $35M and Phoenix would save $37M. But savings would also be seen in the cooler northern areas of the country: $16M for New York and $10M for Chicago.

Roads, sidewalks and driveways coated with dark asphalt can be as much as 70 degrees hotter than similar white or light-colored surfaces because sunlight is absorbed by the blacktop and converted to thermal energy.

Even though you, personally, can’t do much about Los Angeles or Phoenix, you CAN make a difference in your own back yard, literally, by replacing blacktop driveways and walkways with what is called “low albedo” pavement, and planning to switch to lighter-colored roofing when that project becomes due.

In addition to that hardscaping, you can make a major and noticeable improvement to your own environment by planting... trees! Research by leading academic institutions and government agencies continues to show that planting trees will lower the temperature in and around your home and, as a consequence, reduce your energy bills.

There is one very convincing reason to plant trees on your land: Evapotranspiration. Trees transpire water through their leaves, cooling the surrounding air. A single mature tree with a 30ft canopy can transpire as much as 40 gallons a day.

According to the Department of Energy, just three trees planted around a house can save between $100 and $250 annually in heating and cooling costs. (I would guess the savings would be even higher, given current energy costs.)

And here’s another interesting fact: Ambient temperatures are 3 to 6 degrees cooler in tree-shaded neighborhoods. As well as being cooler, homes located on streets lined with mature trees are more attractive and have greater “curb appeal” when it’s time to sell.

If your hometown is woefully lacking in trees, you can do something about it. Find out if there’s a neighborhood tree project. If not, think about getting together with your neighbors and starting one. When you add up the benefits – lower energy costs, aesthetic enhancement, improved resale prices – your neighbors are likely to share your enthusiasm! You can find a lot of information online by going to Google and typing in “neighborhood tree projects.”

Which trees work best to provide shade, save you energy, enhance the environment and are pleasing to the eye? In the next Plant Man column, I will discuss some of my favorites that will provide a feeling of tranquility and keep more of your hard-earned money in the bank!

Meanwhile, here are two useful Web sites I referred to in this column: http://eetd.lbl.gov/HeatIsland/LEARN/ and http://www.energy.gov/news/1652.htm You can click on a direct link to both those Web sites (and more) when you go to www.landsteward.org and find this column under “The Plant Man” heading.

The Plant Man is here to help. Send questions about trees, shrubs and landscaping to [email protected] For resources and additional information, or to subscribe to Steve’s free e-mailed newsletter, go to www.landsteward.org