How to bring shade to a city
Four East Coast cities are using satellite mapping to set environmental goals and plant more trees.
from the August 1, 2007 edition
Page 2 of 3
Using satellite mapping to set goals
Boston is the fourth US city, behind Baltimore; Annapolis, Md.; and New York, to employ the US Forest Service's latest forest mapping technology called the Forest Opportunity Spectrum. FOS fuses satellite images with a flexible model for classifying land parcels and analyzing cities' environmental goals, says Morgan Grove, research forester for the Northern Research Station of the US Forest Service in Burlington, Vt.
The resulting detailed satellite images – close enough to identify individual trees and cars – allow cities to determine current urban tree canopy cover and set goals for environmental improvements, such as Baltimore's desire to improve water quality and New York's efforts to curb air pollution. The four cities are the first to set specific tree canopy cover goals. Mayor Bloomberg in April announced New York City will plant 1 million trees during the next 10 years.
Boston's 29 percent urban tree canopy cover, as determined by the FOS survey, is already above most of its East Coast neighbors. New York City has a 24 percent cover while Baltimore has only 20 percent. Annapolis, however, boasts a 41 percent cover. If Boston's $15 million tree campaign goes according to plan, the trees will be in the ground by 2020 and expected to increase canopy cover to 35 percent by 2030, says Sherri Brokopp, sustainable cities program director of the Urban Ecology Institute. The city has just $3.5 million committed in funding but is seeking additional commitments from the private sector, says Jim Hunt, Boston's chief of environment and energy.
The societal benefits of trees
According to city and environmental officials, the $15 million spent on trees is expected to have social benefits as well. Trees are touted as miracle workers for city problems. Boston officials cite studies claiming that trees reduce energy costs, ease stress, and lower crime rates. Increased vegetation is also credited for decreases in aggressive street behavior, boosts in neighborhood pride, and more people spending more time outside, which serves as increased outdoor surveillance.
Boston is even using the FOS system for a venture into "environmental justice," in other words, equal opportunity trees.
"The question is, does everyone, in terms of race and income, have similar levels of canopy cover in their neighborhoods?" Mr. Hunt says. According to Boston's tree inventory statistics, the crowded and poorer East Boston neighborhood has only 6 percent canopy cover in comparison to the wealthier West Roxbury's 49 percent.
Several Boston environmental organizations are already stepping up their efforts. On this typical Thursday in early July, members of EarthWorks and JP (Jamaica Plain) Trees plant trees in various yards in the Jamaica Plain neighborhood. EarthWorks is a member of Boston's urban forest coalition and reports all tree plantings to the Urban Ecology Institute.
Matt Walter, a certified arborist and JP Trees volunteer, is planting a kousa dogwood in the yard of Jamaica Plain resident
David Baron. [Editor's note: The original version misidentified the organization that Mr. Walter volunteers for.]
"They've given me a lot more guidance than I would have gotten just from walking into some nursery," says Mr. Baron as Mr. Walter explains how often he should water the dogwood. "I really wanted to get a tree, and I heard this program was free."
On this same afternoon, Walter examines a black tupelo tree planted two weeks ago. Upon examining the tree and its dried brown leaves, Walter unearths it and pointedly says, "Some trees make it. Some trees don't."
He soon determines the tree grew a double trunk flare, likely caused from repotting in the nursery. The double flare caused a water shortage to the deep roots, he says, and promises the homeowner a new tree will be on its way.
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