Tacoma’s challenge: Making City of Destiny more a City of Trees

Downtown Tacoma is barely visible over the lush canopy of McKinley Park, October 5, 2015.
Downtown Tacoma is barely visible over the lush canopy of McKinley Park, October 5, 2015. Staff photographer

Up in the mid-boughs of the giant sequoia in Tacoma’s Wright Park, the world suddenly flips over.

Somewhere down below are people, their voices and faces small and far away.

Above, all around are thick, wet needles and a solid, rough trunk, a world that’s slower, fresher, wider.

It’s the world of the tree canopy — one that Tacoma needs to help keep its air and water healthy.

But a recent city goal to nearly double the canopy to 30 percent by 2030 raises all kinds of questions, from how much is enough to the challenges of getting there.

“We use tree canopy as an analogy for environmental health … and what we want is a healthy environment in Tacoma,” said Jim Parvey, an engineer who manages the city’s office of Environmental Policy and Sustainability. “(But) in order to get to our 30-by-30 goal, we have to engage the community.”

It’s actually been a goal for five years now, although only this year has the city stepped up its planting efforts, from freeway corridors to business districts to open spaces.

The goal began in 2010, when Tacoma adopted an Urban Forestry Policy to help citizens, businesses and agencies “promote, conserve, protect and improve” the city’s urban forest.

At that time, Tacoma’s canopy cover was thought to be 12.9 percent of the land area — less than half the national average at the time and comparable to intensely developed cities such as San Francisco and Chicago.

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Working off a study by American Forests, a national nonprofit conservation organization, the city crafted a goal of increasing the canopy to 30 percent by 2030, though the study recommended 40 percent.

“We looked at what was possible and settled on 30 percent,” Parvey said.

Initial efforts included an artist project, free tree workshops and public information outreach in a program then called Evergreen Tacoma.

One year later, the goal got a little clearer, thanks to new image data from the University of Washington’s Remote Sensing and Geospatial Analysis Laboratory.

The data fused traditional aerial photographs with laser-made 3-D LiDAR images and crunched the resulting maps through software originally made for scientists by the Brazilian government.

The result for Tacoma showed canopy cover was in fact 19 percent.

“Traditional sensing has a coarse resolution — you can see parks but not streets, for example.” explained Monika Moskal, associate professor of remote sensing at UW, who led the project. “Now you can see smaller trees that (weren’t visible on older images but) have quite a bit of impact.”

Other cities, including New York (with 21 percent canopy cover) and Baltimore (27.4 percent) have used the technology, with the help of U.S. Forest Service software, to determine their canopy number.

Moskal points out that with newer imagery, cities can better analyze which neighborhoods have or need trees: large parks (visible on the old maps) tend to be in wealthier areas, whereas street trees (visible on the new) might be in less well-off locales.

This theory is born out by a study comparing canopy data with socioeconomic areas of Tacoma, which showed that low-income areas generally were those most in need of trees.

“You can see how tree canopy is serving different socio-economic communities,” said Moskal, who also analyzed canopy cover for Seattle, Olympia and Bainbridge Island.

Tacoma now has individual canopy goals for each business neighborhood.

Armed with the new canopy cover number, city officials met with representatives of the business neighborhoods in 2011 to develop an inventory of trees and an urban forest management plan.

The city also planted some Garry oaks near the South 38th Street interchange to Interstate 5 in 2013.

By 2014, Tacoma also had developed an Urban Forest Manual, updating code requirements for landscaping on new and revised developments.

In March 2014, the city pioneered the state’s first “DePave” program, ripping up portions of the concrete sidewalks along Sixth Avenue and planting trees.

But 2015 saw the most action on the canopy goal.

In April, City Councilman David Boe dug the first shovelful for a planting of 75 bur oaks, ashes, elms, cedars and sequoia along I-5 near South 84th Street.

Volunteers plant trees and small plants in sections of a parking strip along East McKinley Avenue in October. (Peter Haley, staff photographer.) 
Volunteers plant trees and small plants in sections of a parking strip along East McKinley Avenue in October. (Peter Haley, staff photographer.)

In October, the McKinley DePave Project — a partnership with the Pierce Conservation District and McKinley Business District — saw dozens of residents turn out to plant trees along sidewalks.

The ponderosa pine, bar oak, cutleaf purple beech and mountain hemlock, as well as shrubs and ground covers, replaced 7,000 square feet of concrete in the business district. Trees were selected for their suitability in trafficked zones and their resistance to pollution, drought and wind.

And in December, the city began planting a native forest of more than 400 trees (mostly Douglas fir and Western hemlock) on the steep slope above Schuster Parkway, part of a larger management project to stabilize the eroding bluff and control stormwater.

The city’s budget for urban forestry is $200,000 annually.

The American Forests report did not suggest a dollar figure for city forestry budgets, but did recommend cities take the economic value of trees into account when making decisions.

The Society of American Foresters calculated that value in 2007 to be between $19 and $25 per year for medium-sized trees, and $48 to $53 for large trees — a 250 percent return on investment for every tree planted when it reached maturity.

Why the focus on tree canopy? For city engineers like Jim Parvey, whose role (among other things) is to develop plans to achieve the 30-by-30 goal, trees are crucial city infrastructure.

“Trees filter stormwater, they reduce the peaks of floods … and they reduce greenhouse gases by sequestering carbon,” he said.

Trees also produce oxygen and cool the air — fairly essential elements for human existence — as well as support wildlife and a healthy ecosystem.

But there’s also the human element.

“Studies show that trees in business districts increase profitability by 12 percent compared to grayscape,” said Melissa Buckingham, water quality program director at Pierce Conservation District.

Trees also add property value and reduce crime rates.

But, added Buckingham, they also do things you might not measure: slow traffic, reduce noise, cool sidewalks to encourage walking.

“They’ve found more community built around trees — more safety and shade,” she said. “They have social value.”

And then there’s that feeling when you climb a tree — like the giant sequoia in Wright Park that MetroParks helps kids climb every Arbor Day — a feeling of something bigger, taller and deeper than ourselves.

As environmental writer Nalini Nadkarni puts it, it’s a connection between species that we need emotionally and even spiritually.

Still, though Tacoma has just 15 more years to make the 30 percent canopy goal, there’s a lack of urgency around the effort. Several city programs are centered on trees, but “nothing is really focused on achieving that number,” Parvey said.

A new Environmental Action Plan by the city (which includes tighter regulations on street trees) is slated to be finished in February, but many of the steps tied to it will have to wait until the 2017 budget. (Comments on the plan can be made through Thursday (Jan. 7) at tacomaeap.publicmeeting.info.)

And even measuring how far Tacoma is getting with tree coverage is a challenge.

“We know how many trees (the city) is planting,” explains city arborist Mike Carey, adding the city will soon get funding from the state Department of Natural Resources to do an inventory of city-owned trees.

“But we don’t know what citizens are planting or removing. We don’t have a system in place to analyze it. … It’s such a big animal, it’s hard to know what we have. This is a first stage.”

There are plenty of challenges, too, in getting to 30 percent canopy. For one thing, most of Tacoma is not even under the city’s control: it’s owned by citizens or businesses, or includes right-of-ways where property owners are responsible for trees.

Then there’s climate change, which not only affects the health of already-planted trees but also presents difficulties in knowing which trees will still be thriving in 15 years.

But even though the 30-by-30 goal is tough, it’s worth keeping, say city and outside experts, because it will inspire residents to achieve it.

“Canopy is one way to encapsulate positive change in the urban forest,” said arborist Matt Distler, who recently worked on a plan for Mercer Island’s urban forest. “Having that goal is great, because it’s something people can wrap their heads around.”

“It’s definitely a challenge,” Parvey said. “In order to get to 30-by-30, we have to engage the community.”

Rosemary Ponnekanti: 253-597-8568, @rose_ponnekanti


Curious about tree canopy? Explore these resources.

▪ U.S. city tree canopies (U.S. Forest Service, 2012): 1.usa.gov/1O7ymNg

▪ Do-it-yourself canopy tool i-Trees: (U.S. Forest Service): bit.ly/1xL2HG8

▪ City of Tacoma canopy information, data and tips: bit.ly/225quQM

▪ City of Tacoma Urban Forest Policy: bit.ly/1QrbaKj

▪ International Canopy Network (canopy science): bit.ly/1NvOK4w

▪ General canopy information: Canopy.org

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