Meet my air conditioner. It's 30 feet tall -- a street tree that the City of Pittsburgh planted about 15 years ago, at the request of my wife and me.
Since it matured, the tree, a Bradford pear, has mostly shaded the front of our South Side rowhouse from the afternoon sun. Even on the hottest days, we don't need more than an electric fan. And though our tree can't relieve humidity, the house is usually comfortable enough that visitors have asked whether we have air conditioning. We don't -- one reason our electric bill is one-third that of the typical Pittsburgh household.
In winter, meanwhile, the tree obligingly sheds its leaves. Now the afternoon sun can do just what we'd prefer come January, and warm the joint up.
The city no longer has the money to plant street trees itself. But it is supporting an ambitious venture to bring the benefits of an "urban forest" to more Pittsburghers.
The effort has roots in 2005, a time when the city was removing more trees than it was planting. That year, a street-tree inventory found that a quarter of the city's 31,524 trees in public right-of-ways (not counting parks) were in poor condition or worse.
In 2008, the city, Allegheny County and the state Department of Conservation and Natural Resources joined the Western Pennsylvania Conservancy to create TreeVitalize, a nonprofit on a mission to plant 20,000 trees by 2012. Though the deadline's been pushed back to 2013, TreeVitalize is well on its way. Backed by a combination of government and foundation money, as of spring 2011 the group had planted 10,359 trees in Allegheny County.
The trees have mostly been planted in Pittsburgh neighborhoods, from East Liberty to Manchester, Beltzhoover to Troy Hill, at the request of community groups or coalitions of neighbors. TreeVitalize supplies the trees and equipment; volunteers (or sometimes private contractors) provide the muscle. Another nonprofit, Tree Pittsburgh, trains volunteer called Treet Tenders to care for the trees, especially in their first couple years, when pruning and watering are crucial.
TreeVitalize director Jeff Bergman says one goal is "to diversify the urban forest." Maples were once one-third of all street trees; TreeVitalize now favors other native species, like American elm (a disease-resistant hybrid) and hawthorne. (My Bradford pear, once a popular street tree, is a non-native type no longer planted.)
Thanks largely to the Tree Tenders, TreeVitalize's new trees have a 97 percent survival rate, Bergman says. (The death of a quarter of the 250 trees planted Downtown last year is still being studied.) And tree care is a popular hobby: Tree Pittsburgh will shortly train its 1,000th Tree Tender -- and, says Tree Pittsburgh's Caitlin Lenahan, care for at least 2,800 trees in 2011, twice the 2010 figure.
But trees' benefits, too, are quantifiable. "I talk about [trees] as infrastructure," says Bergman.
Each tree costs about $1,000, if you count the initial two years' care. But the trees earn their keep: A 2008 study completed for Tree Pittsburgh by The Davey Resource Group calculated that our street trees provide services worth $2.4 million annually. The biggest benefit financially is energy savings: Shading houses in summer and providing windbreaks in winter, trees save us $1.2 million in electricity and natural gas.
Other advantages are also environmentally profound. Trees intercept storm water, averaging 1,411 gallons annually per tree, curbing flooding and water pollution. They store carbon dioxide, alleviating climate change. Some species actually absorb air pollution, including components of smog.
The Davey study estimated that trees have also raised property values citywide by $800,000.
Still, when she's talking trees, Kim Collins barely mentions dollars. Through her South Side Tree Project, Collins has gathered signatures to successfully request more than 100 trees for greenery-starved blocks including her street, Wharton. She's also recruited neighbors to plant and tend. "People just love the idea," she says. "It's awesome to see all the neighbors outside working together."
The benefits aren't just social. With just a few new trees, she says, "The whole vibe that you get from that street totally changes." She calls it "almost a calming feeling," adding, "It's funny that a tree can do that much."
TreeVitalize is accepting street-tree applications for the spring 2012 planting through Sept. 9. See www.paconserve.org/216/treevitalize.