By Jim Gersbach | Linear Arboretum Founder, Concordia Tree Team Member
You’re invited to join me on a free walk to explore the Concordia Linear Arboretum Saturday, April 16. The 90-minute walk, sponsored by Portland Parks & Recreation Urban Forestry, will start at 9 a.m. at the southeast corner of 30th Avenue and Ainsworth Street.
Concordia is fortunate to have one of a handful of Portland’s tree-lined medians. It’s a stretch of about 1.5 miles from Fernhill Park to Martin Luther King Jr. Boulevard.
Since 2005, the median – and the right-of-way planting strips on the north and south sides of the street – have been designated by the city as an investigational arboretum.
Here, city residents can get to know less familiar, approved street trees, including ones in a trial for suitability in this climate.
Originally conceived as a grand entrance to the city from the east, Ainsworth was envisioned as a boulevard with a tree-lined median running from the Columbia Gorge to the Willamette River.
The only part ever developed as such is what exists today. The original Ainsworth planting was a classic monoculture – a single species of tree (Acer platanoides) that conformed to the uniform look so prized by European city planners. That made Ainsworth more vulnerable to any pest or disease that especially afflicted maples.
Portland’s mild climate can support hundreds of different tree species. As the city began to allow and then encourage more choices of species, many people still selected only what was familiar. Exposing people to great new options is what the Ainsworth Linear Arboretum is all about.
When trees die, we replace them with diverse species and new cultivars with better forms or disease resistance. Over 16 years, diversity in the median has grown from six to 47 species, and now there are trees native to Oregon.
Many people and organizations have helped. Trees and mulch have been provided by nurseries, Friends of Trees and Portland Parks & Recreation Urban Forestry. The parks folks have also removed dead trees, ground the stumps to enable new plantings and watered young ones for the trees’ first two summers. Members of the city Youth Conservation Crew have weeded and mulched.
Because Portland has experienced multiple drought years, I have handwatered a lot of the trees beyond two years to help them establish.
Editor’s note: CNews space is limited, and there just wasn’t room for all of the information Jim Gersbach provided. To see his full-length story, visit ConcordiaPDX.org/2022-linear-arboretum-tour.
Concordian Jim Gersbach is public affairs specialist for the Oregon Department of Forestry and former urban forestry specialist for the city of Portland. His volunteer activities include serving on the Concordia Tree Team, founding the Ainsworth Linear Arboretum, acting as an outreach guide for the Hoyt Arboretum, and providing education as well as leading planting and pruning crews for Friends of Trees.