PP&R and volunteers finish survey and mapping of 220,000 Portland street trees

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One of largest inventories of city trees in the U.S. will help guide Portland’s urban forestry management.
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(Portland, OR) –

One of largest inventories of city trees in the U.S. will help guide Portland’s urban forestry management.

Portland Parks & Recreation (PP&R) Urban Forestry staff and more than 1300 volunteers have surveyed and mapped nearly every planted street tree (planted in public rights-of-way, rather than on private property) in Portland – almost 220,000 in all, covering all 96 of the city’s neighborhoods. The effort is key to help inform how PP&R manages Portland’s urban forest going forward.

(Photo above: a Street Tree Inventory volunteer smiles as she measures a Portland tree. This endeavor will help guide Portland's urban forestry management.)

Trees have also been measured, identified, and each one’s health rated as part of the City’s first comprehensive inventory of street trees. Findings from the tree inventory, which was completed in September, will be presented at the 2016 Tree Inventory Summit, a free public event:

What:  2016 Tree Inventory Summit

When: Saturday, Nov. 5th, from 8:30 a.m. – 3:30 p.m.

Where:Mt. Scott Community Center 5530 SE 72nd Ave.

Register for the event here.

“Trees are a vital part of our city,” says Portland Parks Commissioner Amanda Fritz. “They improve our health by cleaning the air we breathe and reducing summer heat impacts, provide habitat for wildlife, and make our neighborhoods more walkable and beautiful.  I am pleased that the Urban Forestry staff and our valued volunteers worked so hard on the Street Tree Inventory. Their work will help inform and guide stewardship of this valuable public asset.”

All 96 Portland neighborhoods inventoried

More than 1,300 volunteers, in cooperation with PP&R Urban Forestry staff, systematically gathered information on street trees in all of Portland’s nearly 100 neighborhoods, one tree at a time. Workers and volunteers spent approximately 17,000 hours on the project from 2010 through September, 2016. Reports for individual neighborhoods are already available on Urban Forestry’s web page. Residents are encouraged to check-out the information for their local street trees.

“Partial surveys of street trees were done in Portland in 1938 and again in the 1970s, but this is the most comprehensive and in-depth look at our street trees ever,” says City Forester Jenn Cairo. “Besides Portland, New York is the only city which has attempted anything of this magnitude.”

Cairo says especially significant is that all the inventory data has been entered into a geographic information system (GIS) database, which can be mapped.

“This makes it easier to analyze, study, and share the information with other city bureaus, researchers, and the public,” adds Cairo.

Preliminary findings from the survey have already been influencing the city’s tree-related policies. Examples:

  • Some lower-income neighborhoods and areas with less tree canopy have benefited from more funding from the Urban Forestry tree stewardship program. Strategic tree planting efforts and tree maintenance activities in these neighborhoods help to improve and increase the overall tree canopy for the long term. 
  • Portland is vulnerable to significant tree losses from pests and diseases as a result of a very high count of maple trees along city streets.  Urban Forestry now requires property owners to plant alternative species when replacing and planting new street trees.

 Given the low percentage of evergreen trees being planted, Urban Forestry has increased the number of evergreens on its Approved Planting Lists from a handful to more than 20, and is encouraging evergreen planting.

“Working together with so many volunteers from diverse backgrounds, we were able to gain so much more understanding about street trees everywhere in the city,” says Angie DiSalvo, Portland Parks & Recreation Urban Forestry’s Outreach and Science Supervisor. “The data produced is empowering residents to take science-based actions to improve the urban forest right where they live.”                                   

Other key findings from the inventory include:

  • Portland’s street trees provide $28.6 million worth of environmental and other services to the city annually, and have an overall value of nearly $753 million.
  • Maples and trees in the rose family - mainly cherries, plums, hawthorns, and crabapples – dominate street plantings at levels well above what forestry officials consider healthy. A lack of tree species diversity means the city’s forest is more susceptible to large-scale tree loss

 Neighborhoods in east Portland tend to have more empty spaces than other parts of the city, however street tree populations in these areas are more diverse and contain more desirable evergreen species: Citywide, evergreens make up just 8% of street trees, however in east Portland they make up nearly twice that.

There is an increasing trend to plant smaller-form trees in sites which could accommodate larger trees – larger-form trees offer greater long-term environmental and community benefits.

“We know from other research that a majority of Portland’s neighborhoods don’t yet meet the City’s stated goal of raising the tree canopy level from the current 29% to 33%,” says Cairo. “The inventory findings pinpoint street tree planting trends that are indicators of where neighborhoods are making progress, where additional efforts need to be made, and what the most effective actions to boost canopy might be.”

Portland Parks & Recreation Urban Forestry is responsible for management of the city’s urban forest including tree policy and permitting, responding 24/7 to tree emergencies in city streets, forest assessment and planning, and ensuring urban forest services for current and future Portland residents.

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