Trees Give More than Shade

By Trevor Stokes
Staff Writer

Florence Times Daily


Think trees just cost money to plant, prune and then leave a pile of leaves to rake? Think again.

Trees give back to the tune of $5 million per year in services that include reducing energy costs, absorbing pollutants and collecting storm water, according to new research.

For every dollar invested in Florence trees, the city averages back $5 in environmental services, said Paul Graham, Florence urban forester who headed the study.

For many, the economics of trees involve timber, fruits or nuts, but an emerging field shows that trees themselves can deliver expensive-to-replace environmental services to urban landscapes.

Florence UF Benefits
Highlights from the recently completed study include: trees reduce energy costs by nearly $2.8 million through shade, provide $1.2 million in storm water reduction, nearly $1 million in curb appeal and nearly $90,000 in carbon uptake.

"Trees have not been viewed as an asset," Graham said.

That's changing, according to urban forestry experts.

The emerging science and social movement toward looking at the economic impact of urban forestry goes back 30 years and is now taught in more than 30 schools, said Pepper Provenzano, executive director of TreeLink, an urban forestry nonprofit organization.

Unlike trees in the forest, ones in urban areas can correlate with reduced crime rates as well as reducing pollution, Provenzano said.

"In urbanized areas, heat islands of buildings, concrete and roads are creating their own weather patterns," said Provenzano, adding that trees can reduce these effects.

"The right tree in the right place can significantly reduce energy bills and can absorb fine particulate matter such as near coal power plants," Provenzano said.

In fact, trees are the only portion of a city's infrastructure that appreciates, he said. "All the rest depreciates."

The Florence survey was a joint effort with the Florence urban forestry department, University of North Alabama geographers, the U.S. Forest Service and the Alabama Cooperative Extension System.

The survey counted 36,172 trees in the city, nearly one tree per resident. An estimated 26,500 are on public property, Graham said.

Top Ten Trees in Florence

Species: Percent of Total Urban Forest
Loblolly Pine:                 15.35%
Crape Myrtle:                   8.93
Sugarberry:                     6.97
Kousa Dogwood:            6.65
Silver Maple:                    5.13
Willow Oak:                     4.76
Red Maple:                       3.96
White Oak:                       3.77
Bradford Pear:                 3.73
Green Giant Arborvitae:  3.65

Source: City of Florence Department of Urban Forestry

Combining the survey with global positioning data, there is now a map of every tree in the city, with species, tree height, trunk diameter and canopy area.

Federally developed USDA software translated the tree data into total leaf surface area, storm water slowdown and uptake of carbon dioxide, a gas involved in global warming.

Tree economics hit close to home for the urban forestry department this year, when its office lost its air conditioner in May and two shading willow oaks kept the interior temperature around 80 degrees in one of the hottest summers on record, Graham said.

"We probably saved $1,500 in electricity costs," Graham said. "It got a bit stuffy in the afternoon."

Surprisingly, trees also come at an environmental cost. Less than 1 percent of the total tree value cost the city $44,000 from reduced air quality, predominantly from a tree-produced plant-defense gas released from loblolly pines. The pines constitute roughly one of every eight trees in the city.

"In comparison to the positive, the negative is miniscule. It's a protective part of the tree," Graham said. "We don't want to get a backlash of people chopping down their trees."

But, beyond reducing electrical bills and storm runoff, trees also have more subtle effects.

"One of the misunderstood parts of the value of trees is the intangible, the 'curb appeal,' " said Leon Bates, who became the city's first urban forester in 1997 and is now retired.

"Planting a tree has a latent effect. When the money is spent, you don't see an immediate return," said Bates, who was involved in planting several trees along Court Street and in McFarland and Deibert parks when he started 10 years ago.

"The early plantings are beginning to exert benefits on the city landscape," he said.

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