By Midge Pierce
SE Portland’s urban street trees get middling grades based on data from a recent tree summit at the Mt. Scott Community Center that reviewed five-years of information collected by more than 100 volunteers from 15 neighborhoods.
The report by Portland Parks and Recreation indicates Portland has significant challenges as trees age and developers uproot healthy specimens.
A key problem is Portland’s lack of genus and species diversity. The canopy also features too many small-stature trees and wrong trees planted on the wrong lots.
To counterbalance these challenges, the staff recommends greater variety as well as large form trees, especially on lots that are 6 feet wide without overhead wires. Evergreens like Douglas Firs offer the most environmental advantages with air and water purification benefits and year-round habitat for countless animals.
“Native evergreens are something we want to retain,” said neighborhood coordinator Julie Fukuda, lamenting that they are rare in recent plantings. “It takes advocacy and education to retain large trees.” Small plants on a large site is a missed opportunity.
While the inventory surveyed trees in public rights of way only, staffers were adept at pointing to opportunities builders have to plant trees on developing lots. New engineering methods, soil that contains gravel and sidewalk bump outs can accommodate root growth for big trees. “The cost of repairing a sidewalk is nothing compared to the value of losing a large tree,” said a speaker.
The three SE neighborhoods fare better than communities farther East. Montavilla, with a whopping 6188 trees in public rights of way, has more trees than any neighborhood including Irvington in terms of sheer numbers, but Montavilla is the largest, most spread out of the neighborhoods studied, so its canopy is actually thinner than others.
Likewise, Montavilla fared comparatively well in terms of tree varieties. Yet again, the neighborhood’s large size offset the statistic.
In all the neighborhoods studied, including Buckman and Mt. Tabor, the Norway maple is the most common tree. It is now on a nuisance list despite the popularity of its colorful, fall foliage.
In fact, maples of various kinds comprise more than a fourth of Portland’s trees. Cherries and plums are overly prevalent too. Lack of diversity makes Portland’s tree canopy vulnerable to disease, climate change and pests.
Irvington is most at risk, with 52% of its street trees at risk of infestation in the next five years or so. Buckman also fails the diversity tests, a factor that could devastate its tree coverage and impact area air quality and aesthetics.
Buckman has room for 2300 more street trees, Mt. Tabor has room for 2700 and Montavilla has spaces for a whopping 4465 trees. Both Mt. Tabor and Montavilla have tree stocking levels below 55 percent.
Speakers encouraged prioritizing by planting in the biggest available spaces first with large form, high “performing” trees, meaning those that provide the highest level of benefits over the years.
Misconceptions that tall trees are unsuitable in commercial areas were bashed. Tall trees with branches that can be trimmed up can be more appropriate than small, ornamental trees that block storefronts and signage.
One obstacle with no easy answer is the cost of tree maintenance. Homeowners are responsible for street trees as well as their own, a factor that may discourage new plantings.
One remedy is a Treebate program enabling homeowners who plant new trees to receive a credit on city water/sewer bills. Contact: portlandoregon.gov/bes/treebate
As a next step, neighborhood tree teams are being set up to advise residents about care, maintenance and the planting of the right tree in the right place.