(Robert J. Gibbs, AICP, ASLA, July 15, 2016)
Trees are an indispensable component of good neighborhoods. When the right species are planted in the right place and cared for properly, many benefits are realized. Street trees soften hardscapes, buffer pedestrians from moving vehicles, and create “outdoor rooms” that are pleasing to walk through. They help to reduce traffic speeds, reduce the load on drainage infrastructure by absorbing precipitation, remove millions of tons of CO2 emissions annually, and extend pavement life with their shade. There even is compelling research that motorist road rage is less in green urban versus stark suburban areas.
They also increase property values. U.S. Forest Service economist Geoffrey Donovan and National Institute of Standards and Technology economist David Butry analyzed 2,608 single-family home sales in Portland, Ore., between July 1, 2006, and April 26, 2007. They discovered that homes with street trees sold for an average of $7,130 more than homes without street trees. The Forest Service also puts its findings in percentage terms, stating that healthy, mature trees add an average of 10 percent to a property’s value.
Other studies point to a marked bump in real estate value when street trees are part of the mix:
~An August 2007 article in Arborist News says that the presence of larger trees in yards and as street trees can add from 3 to 15 percent to home values throughout neighborhoods.
~A USDA report, “The State of California’s Street Trees,” called the effect of street trees on property values “the single largest benefit in California, averaging $91.89 per tree … and reflects higher median home sales prices in California.”
Location, location, location
To accomplish the greatest good and reach those impressive ROI numbers, street tree strategies must be carefully planned and executed.
First, get the location right. Street trees must be planted between the sidewalk and curb, not in the middle of individual front yards. Placing street trees along the street edge makes streets appear narrower, slows traffic speeds, and makes individual front yards appear larger. Placing trees in front yards makes the street appear wider and the yards smaller. The latter approach sends a silent, unwanted message to motorists: Drive faster.
Proper species selection is just as crucial as location. Many larger cities have tree lists appropriate for their climate. The best lists include mature height and spread, the minimum boulevard width into which they should be planted, and suggestions for appropriate locations, such as beneath power lines.
In Michigan I recommend sugar maple, red oak, horse chestnut, gingko, linden, and sycamore. New, disease-resistant elm species such as ‘Liberty’ elm have proven suitable for Michigan and provide a nice branch structure. They were successfully installed at Cranbrook Schools about 20 years ago.
Some trees are poor choices for Michigan streets. Ornamental trees such as crabapple, cherry, pear, dogwood, and serviceberry should be avoided because they don’t get large enough to provide shade or calm traffic. They are also out of scale for typical streets. Norway maples and Crimson King maples are too dense; they’ll block the sun and kill grass. Honey locust trees are too lacy and have poor branch structure. Red and silver maples are too brittle and also should be avoided.
Maintenance is key. Street trees should be pruned regularly during the first several years of their lives, so their limbs and canopies mature in a balanced manner. This will help steer them toward health and prevent growth patterns that earn them an unwanted “danger tree” designation decades later.
Robert Gibbs, is the President of Gibbs Planning Group (GPG), founded in 1988. Gibbs was one of the architects of Birmingham’s Master Plan to rejuvenate its downtown 20 years ago and is a recognized leader in “New Urbanism” movement. Gibbs is a published author of two books regarding urban planning and retail and is a Harvard professor teaching” Urban Retail Planning” at the school’s Executive Education Program graduate program.
Gibbs has been profiled in such national publications as the New York Times, Wall Street Journal and the Atlantic Monthly and was honored for his life’s achievements by the Clinton Presidential Library in 2012.