Bits 'n' Pieces: Master gardeners prove trees are the coolest friends we've got

By Scott Hewitt, Columbian social issues & neighborhoods reporter

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Who are your BFFs on these scorching summer days? Trees, of course.

Master Gardener Erika Johnson and a handful of her green friends flocked to Esther Short Park last weekend to prove it. They were literally green as they did so — dolled up with leaves and branches and other arboreal fashion statements.

"We dressed up in green to be intentionally visually provocative," Johnson said. "We really wanted to call attention to the heat island effect."

Cities are heat islands. Buildings and pavement absorb and retain more solar energy than rural areas and forests, driving temperatures higher. Trees, on the other hand, provide shade and "evapotranspiration" — sweating — that leads to cooler conditions.

How much cooler? You'd be amazed. The master gardeners, wielding a laser thermometer and taking readings all around the park, challenged passers-by to consider just how dramatic the differences might be between, for example, black pavement, white sidewalk and grassy areas of the park, both sunny and shaded.

Nobody suspected the spread to be as much as 45 degrees, Johnson said. Exposed pavement was measured as high as a sizzling 113 degrees, while the shade beneath the park's biggest trees went as low as a comfy 68. That's the difference between a pleasant summer day and a heat emergency, and it demonstrates the extreme friendliness of a well-developed tree canopy.

"If you were to fly over your own neighborhood in an airplane, you'd want to see it … obscured 40 percent by trees," Johnson said. That's the goal set by American Forests, the nation's oldest nonprofit conservation agency. A 2010 study assessed Vancouver at 18.4 percent canopy-covered overall, and the official goal is 28 percent by 2030. Individual city neighborhoods vary widely, Johnson said, and it's not surprising to note that wealthier neighborhoods enjoy the most canopy coverage (historic Heights neighborhoods such as South Cliff and Dubois Park are in the 40s; less wealthy Fruit Valley and Meadow Homes are down around 11 and 13 percent, respectively).

Aside from sheer creature comfort, the benefits of tree coverage are impressive. Strategically positioned trees keep buildings cool and cut air-conditioning costs and energy usage; trees also offer cleaner air, stormwater mitigation and higher property values. Science has even shown that people's health and moods are better and crime is reduced where there are more trees and less asphalt, Johnson said. Check out the city's Urban Foresty website, cityofvancouver.us/publicworks/page/urban-forestry, for a ton of information on the value of trees.

Now that you know your real BFFs this summer, here's the next step: help celebrate the 25th anniversary of Friends of Trees, a Portland nonprofit, by planting more trees where you are. Friends of Trees offers street trees for $25 each and yard trees for $50, and organizes volunteer planting days to get them into the ground and their new owners educated about their care. Vancouver planting dates in the next year are: November 15 in southeast, Cascade Park and Fisher's Landing (sign up by Oct. 13); Jan. 17 in central Vancouver (sign up by Dec. 15); Feb. 21 on the west side (sign up by Jan. 19); and March 14 in northeast (sign up by Feb. 9).

Signing up and placing your order before the deadline is essential. Contact Friends of Trees at 503-282-8846 or visit www.friendsoftrees.org.


Bits 'n' Pieces appears Fridays and Saturdays. Email bits@columbian.com.