Portland’s growing tree canopy provides many benefits

Photo Credit: OHS.org

Once nicknamed “Stumptown” for the massive clearing of trees during a phenomenal period of growth in the 1800s, Portland now proudly protects, encourages and monitors the growth of its expansive tree canopy and is dubbed a Tree City USA community.

In collaboration with the Arbor Day Foundation, the U.S. Forest Service and the National Association of State Foresters, the Tree City USA program “provides direction, technical assistance, public attention, and national recognition for urban and community forestry programs” across the nation.

Portland has held the title of Tree City USA almost since the Arbor Day Foundation began the program in 1976.  The benefits of Portland’s dedication to being a Tree City USA for the past 35 years permeate the entire city.

According to a recent news article in the Oregonian, “an aerial imagery study released by the Portland Bureau of Parks and Recreation shows that the city’s tree canopy has grown by 2.6 percent over the past 10 years, and now covers nearly 30 percent of the city.”

Photo Credit: ColumbiaRiverImages.com

The Arbor Day Foundation has compiled information from various sources regarding the many benefits urban trees provide environmentally, economically, and socially for millions of Americans.

The Tree Canada Foundation asserts that “one tree provides oxygen for up to four people in one day.”

According to the Oregonian, “Portland has approximately 240,000 street trees, and 1.2 million trees throughout Portland’s parks.”

The U.S. Forest Service has determined that urban trees in the Chicago area filter an estimated “6,000 tons of air pollutants each year, providing cleansing valued at $9.2 million.”

And, according to a 2009 Parks Bureau study, the ecological benefits of Portland’s street and park trees are valued at $27 million annually.

Photo Credit: Oregonian

Other benefits of urban trees include better air, soil, and water quality, lower occurrences of asthma and stress among children, increased carbon sequestration, and reduced energy use for heating and cooling.  In fact, the International Society of Arboriculture has revealed that the shade and shelter provided by trees, annually reduces heating and cooling costs in the United States by $2.1 billion.

Mark Ross, Parks Bureau spokesman, states that Portland’s next goal will be to achieve a “33 percent urban tree canopy by 2030.”

Portland residents will surely enjoy and appreciate the many benefits a robust urban forest reaps for years to come.

One Comment

  1. One of the great challenges in tracking tree canopy change over time is that the accuracy of mapping high-resolution tree canopy is somewhere to within +/- 2 percentage points if done well (e.g. if the map says the tree canopy is 30% it could be as low as 28% or as high 32%). When Portland purports to have an increase of 2.6% it is important to note that the increase may very well be within the margin of error and tree canopy could have even declined slightly. Regardless, no one is mapping tree canopy to an accuracy within tenths of a percent making the use of significant digits highly misleading. By no means do I wish to detract from the great work taking place in Portland, but end users of tree canopy maps do need to be aware of the potential accuracy issues.