Arborist, educator and author Casey Clapp connects people to the positive benefits of trees
By Becky Barrett
Trees have a tremendous impact on people’s well-being, according to Casey Clapp, ’12.
An arborist and dendrologist, and co-host of the popular podcast Completely Arbortrary, he shares his enthusiasm for trees widely, helping people connect to nature around them — whether deep in the forest or just outside their doorstep.
“Every single week I go down a new rabbit hole about how trees work,” Clapp says.
His drive to make science approachable to all audiences is one of the reasons he was selected as a 2025 OSU Changemaker. The program, a part of the OSU Days of Service, celebrates Beavers who meaningfully transform their communities or fields of interest through their careers or volunteer work. By blazing a path toward strong communities, health and prosperity and climate solutions, Clapp underscores the profound impact that even modest efforts can have.
The premise of his podcast is how everything relates to trees. He teaches people how to identify trees and shares what makes each tree unique, drawing connections to topics such as religion, history, culture, biology and ecology.
“Trees affect people in every realm of our existence,” he says.
Clapp grew up in Milwaukie, Oregon, and recalls camping trips with his friends and cousins and spending time at the beach in Florence with his grandparents.
“I’ve always loved to be out in nature,” Clapp says. “I would walk around and pick up sticks, rocks, shells — all sorts of things.”
In high school, he took an aptitude test that suggested he should study landscape architecture. So, he took up the subject at the University of Oregon. He quickly decided it wasn’t what he wanted to do and switched to theater. He was earning Bs and Cs in his new major but kept his interest in trees. In a class on tree identification and physiology, Clapp earned top marks.
“I took the hint and decided to transfer to Oregon State,” he says.
While completing a forest management degree in Oregon State’s nationally No. 1-ranked College of Forestry, he took advantage of an exchange program with the University of Massachusetts, Amherst, where he went on to earn a master’s degree in environmental conservation.
He credits Oregon State Senior Instructor Paul Ries’ arboriculture class — and later, Ries’ mentorship — with sparking his career. Between landscape architecture and forestry, it was the perfect middle ground to concentrate his efforts, applying how trees have a positive impact in urban settings. He worked as a consulting arborist in Seattle and later as a tree inspector for the City of Portland.
Then, about five years ago, Clapp was featured on a podcast called Ologies with Alie Ward.
“Of all the dendrologists in the world, she reached out to me. It ended up kicking off my career as a podcaster,” he says.
In addition to Completely Arbortrary, Clapp volunteers leading tree walks and is on the Portland Urban Forestry Commission. He’s also just written The Trees Around You, a Pacific Northwest urban tree identification guide that covers over 350 species with more than 900 photos. The book is due out in October 2025.
As an arborist, educator and author, Clapp wants to open people’s eyes to the benefits of trees.
It’s not just that trees look nice and make us happy, noted Clapp’s OSU Changemakers nominator.
“Casey believes that a space, whether a backyard or city neighborhood, has an immense impact on the people who live, visit and work there, and few things can alter the nature and quality of that impact more than trees.”
Feeling inspired? Join the OSU Changemakers in making a difference: Participate in the OSU Days of Service throughout May. Join a project organized by fellow Beaver volunteers, start your own or log your hours for any personal service projects accomplished in May.