The need had been well known for a long time. At least back to the early 1990s, conservationists and scientists in greater Portland talked about needing a good map of the region’s Oregon white oak trees. The trees are the foundation of several types of habitat, including woodlands and savannas, and more than 300 plants and animal species rely on them. Conservationists had an idea about where rich remnants of the trees were, but a good map, a map that showed each and every white oak, would unveil connections and patterns; a good map would help focus restoration efforts.
But who would count the trees? Who would plot the data? Who would sit their bottom down and do the job?
Between costs, other restoration priorities, and a huge practical question of how to even do the count, the map remained unmade.
The need kept showing up.
Lori Hennings and Ted Labbe looked at images like this as they mapped the Oregon white oaks in greater Portland.
In 2012, Metro decided to try to make the map. Metro scientist Lori Hennings and oak expert Ted Labbe, who now leads the Urban Greenspaces Institute, were hopeful they had a fix for the “how” question. The team, with help from modeling experts, planned to teach a computer to spot oak trees using aerial photographs and LIDAR images (which show topography like hills and even trees).Oregon white oak is the only oak native to this part of the state. Since time immemorial, Indigenous people in the region have cultivated oak habitats by using fire, which the thick-barked oak trees survived as it burned up competitors like Douglas firs. With the colonization of the Willamette Valley by white pioneers, the trees were cleared away for farming and homes. The stumps of Stumptown included lots of oaks. Now, the trees cover less than 10 percent of their former range, and they are the primary focus of restoration efforts across greater Portland.
In an aerial photograph, it’s impossible to make out all the usual features that help identify a tree. You can’t see the leaves, the height is impossible to eyeball, and their shapes are all the same: every tree looks like a ball of moss. In forested areas, it’s hard enough to tell where one tree begins and one ends, never mind what kind of tree it is.
It seemed like the perfect use of a computer’s ability to find patterns and see what our impatient eyes miss. But first they needed good data on where oaks were, matching a GPS point to an aerial photograph so the machine could start seeing the patterns.
Hennings and Labbe began working with Sequoia Breck and Savahna Jackson, two Indigenous community members who, while college students, led a volunteer team of more than 100 community scientists to go around greater Portland, hold their phones next to oak trees and record the GPS data.
The team took all this data, collected with so much heart and care by so many people, plugged it into the computer, ran the cutting-edge learning program, and the computer … couldn’t figure it out. It would miss oaks that were there and find them where they weren’t.
Hennings tried to troubleshoot the program, refining the GPS data, coaxing the computer to find the trees. It just couldn’t do it, not well enough to make a good map.
One of the ways to recognize them is they're very deep green like broccoli, like a good, healthy head of broccoli.
As Hennings and Labbe stared at the aerial photographs, knowing there was an oak there, lining the image up with GPS data that Breck and Jackson collected standing next to the tree, being able to see the tree themselves but unable to get the computer to see it, their own eyes became able to spot them. “One of the ways to recognize them is they're very deep green like broccoli, like a good, healthy head of broccoli,” Hennings says. “You start to be able to get the color and the texture of these things, and I got better and better at it.”
So they ran their process in reverse. Hennings scoured aerial photographs for oak trees while the team went to that section of the region and recorded what they found on the ground. Every so often Hennings would miss an oak obscured in a cluster of other oaks or growing under a Douglas fir, hidden from the aerial camera. Sometimes a tree had been cut down. But ultimately, Hennings’ eye was way more accurate than the computer. Her eye could make the good map.
Labbe realized what this might mean for the next few years of his life. “I was skeptical, ‘You’re not thinking we can do this for the whole region,’” he recalls saying to Hennings. And she said, “‘No, I think we can.’ And I tried to talk her off the cliff.”
Instead, he jumped off it right after her.
For the next two years, Hennings and Labbe spent hundreds and hundreds of hours staring at aerial photographs, clicking on oaks. Hennings alone found more than 100,000 trees.
Each dot on the oak map represents a tree. These are some of the trees mapped in and around Gladstone.
This type of science is not flashy, it’s not charismatic. It’s cubicle work. It’s boring. It’s invisible work. And in science, as in every sphere of American life, invisible work is most often done by women.“I've always loved oak trees, but I never really thought that, as a scientist, I would be spending hundreds of hours laboring over a hot computer screen picking out oak after oak, after oak, after oak,” Hennings says. Luckily, she likes a good treasure hunt, and the micro-dopamine hits from finding the trees helped her through the tedium.
Until the film Hidden Figures, few people knew that Katherine Johnson and other Black women working in a segregated NASA crunched the numbers for Mercury and Apollo space missions. At Harvard, Williamina Fleming and Annie Jump Cannon led a lab staffed by women who mapped and categorized the stars, setting the stage for enormous breakthroughs in astrophysics. Marie Tharp processed mountains of sonar data that she turned into maps that helped her find continental rifts and built our understanding of plate tectonics.
And so another map has been produced from a woman’s labor, not of the heavens or ocean floors, but our backyards and nearby woods. Hennings is quick to point to the collaboration that created the map: Labbe suffered through his own tedious hours, mapping roughly half the trees; Breck and Jackson’s organization and work; and the 100-plus community scientists holding their phones next to an oak. “They started that data collection for us,” Hennings says. “We really couldn't have done it without them.”
The mapping is done now, which means the analysis can begin, which opens up new restoration strategies and priorities. The Clackamas Soil and Water Conservation District is using the oak map to partner with private landowners to conserve oak habitat. A regional prioritization scheme is under way. Oak restoration workshops have been held. More projects will start soon.
The future of greater Portland’s oaks will be guided, in large part, by this map. It will show up in reports and plans and stories, and it will seem like the sort of thing that must have always existed.
But it was created, one click at a time.
Make the map better
If you know of a tree that isn’t on the regional map, you can get it added. Email Metro scientist Lori Hennings and let her know where the tree is.
Email Lori