Caltech Y Volunteers Remove Ivy at the LA Arboretum for Make-A-Difference Day

Caltech Y volunteers remove ivy from plant life at the Los Angeles County Arboretum and Botanic Garden. (Photo: Otis Otieno)

On April 11, Caltech students traveled to the Los Angeles County Arboretum and Botanic Garden in Arcadia for a Make-A-Difference Day service project organized by the Caltech Y. Volunteers spent the morning removing Algerian ivy from tree trunks and root systems, helping protect the Arboretum’s plant life from invasive overgrowth.

The 127-acre Arboretum, established as a public garden in 1947, sits on historic Rancho Santa Anita, once known to the native Tongva people as Aleupkigna, or “the place of many waters.” Developed by Elias J. “Lucky” Baldwin in 1875, the site now serves as both a public garden and a conservation space for plant species native to Southern California and beyond.

Otis Otieno (ACM ‘27, Blacker), who helped organize the trip, described the Arboretum as a distinctive ecological and cultural site within Los Angeles. Originally, he said, the Arboretum was founded in part to provide protected space for endangered Southern California plant species, including Engelmann oaks. The Engelmann oak, also known as the California blue oak, has long provided food, material, and spiritual connection for Indigenous communities. In recent years, Otieno said, the Arboretum has also expanded to include plant species from other parts of the world, helping create a rich habitat for resident and migratory birds.

“This has enhanced urban biodiversity,” Otieno said, “as various resident and migratory birds now consider it a vital sanctuary.”

For volunteers, the day’s main task was removing ivy. Otieno explained that Algerian ivy competes with intended plant species for water, nutrients, and space. During the service project, students saw how ivy could wrap around trees and send roots into nearly every available crevice in the ground.

“This is the equivalent of a human being constricted by mini-pythons all working together,” Otieno said. Some ivy, he added, climbs trees in search of sunlight, competing with the host tree’s own foliage.

For Elin Stenmark (Ay/Planetary Science ‘26, Venerable), the work was both useful and restorative. Stenmark, who grew up around forested Swedish landscapes, said she was especially excited to spend time outdoors.

“It was satisfying to see the instant results of our weeding, which scaled proportionally with effort,” Stenmark said, “something that is not a regularity in my day-to-day life of problem sets and research undertakings.”

She added that the Arboretum was “gorgeous” and that it was a privilege to play a small role in its stewardship. Though she had never visited before the Make-A-Difference Day assignment, she said she plans to return before graduation.

Beyond the immediate ecological task, Otieno said he hoped volunteers would leave with a broader sense of humility and responsibility.

“My bare minimum for volunteers is just to take a break from Caltech, or life in general,” Otieno said. “Being outdoors instills humility in volunteers that there are bigger forces in life and the knowledge that while man is the biggest evolutionary force in the world, he can also be a steward of the natural world.”

He also hoped the visit would encourage students with interests in plants, birds, and conservation to keep those passions alive. During the trip, he recalled being impressed by a student who spent time spotting birds and describing their behaviors after the volunteering activity.

For Stenmark, Make-A-Difference Day has become a personal tradition: a way to step outside Caltech and give back to the broader Pasadena and Los Angeles community. She noted that the timing, early in the term, makes it easier for students to participate before workloads intensity.

“I’m also appreciative of the generous Caltech Y staff and volunteers, and student site leads, who go to great lengths to make MAD Day an accessible and enriching experience,” Stenmark said. “The programming from the Y has absolutely inspired me to seek out more volunteering opportunities at Caltech and beyond.”

The Caltech Y has worked with the Arboretum for several years. Otieno said this was his third year volunteering there, and that relationships with the Arboretum predated his own involvement. In the past, students have often volunteered individually, but he sees potential for a more sustained relationship.

“There is the possibility of setting up consistent volunteer opportunities,” Otieno said. He added that volunteers may also be able to participate in a program to become certified arborists, an opportunity he hopes to pursue and make more accessible to students.

For now, students and community members can get involved through weekend volunteering and the certified arborist program. Otieno also said there have been discussions about a future Caltech Y 5K through the Arboretum, with funds donated to support the garden.

“Lots of planning,” he said, “but there is more coming for sure.”

Scan the QR code to explore volunteer opportunities at the Arboretum, or click here for more information.