Dec. 13, 2016

Contact: Jay Thompson

Cal Poly Salutes its Best-in-U.S. Urban Forest with Fall Arbor Day Planting

SAN LUIS OBISPO — Cal Poly, recognized as an Arbor Day Foundation Tree Campus USA, hosted a Dec. 7 tree planting to honor the university’s commitment to its trees on what is the nation’s most-diverse urban campus forest.

The event was coordinated by Landscape Services Manager Ron Hostick, whose department maintains the campus’s 320 landscaped acres, and Matt Ritter, a biology professor and director of the Cal Poly Plant Conservatory.

“It’s our Tree Campus USA Arbor Day celebration,” Hostick said, “because fall is the best time to plant trees.”

Students from Jessica Adinolfi’s Botany 121 class, introduction to plant biology, helped plant a pair of valley oaks (Quercus lobata) in the greenbelt between the second and third floors of Faculty Offices North building (No. 47). This species — the largest of the North American oaks — typically grows in interior valleys and foothills such as those around Paso Robles, from Siskiyou to San Diego counties.

Ritter, a renown expert and author on trees, observed that the rainy season of the Central Coast (and other Mediterranean climates) is a more ideal time for planting than during spring Arbor Day celebrations found elsewhere in the state and nation.

Cal Poly was first named a Tree Campus USA by the Arbor Day Foundation for 2014. It is unique among the nearly 300 Tree Campus USA universities in 46 states, Washington, D.C., and Puerto Rico, Ritter said.

“This is a special campus,” he said, “because we have so many different species, which beats any other campus in the United States.”

Hostick said a complete inventory of campus trees was completed for maintenance purposes last year.

“I have 6,600 trees inventoried in the campus core alone,” he said. “Cal Poly has the largest variety of tree species on a university campus in the nation. Of the 6,600, we have 547 varieties. We have 215 single-tree species. The coastal live oak (Quercus agrifolia) is the most common, with 563 trees.”

In addition, the campus is home to two national champions listed on the Urban Forest Ecosystems Institute’s Registry of California Big Trees.

“There’s the red gum across from the Baker science building and karri gum up in Poly Canyon,” Ritter said.

The River Red Gum (Eucalyptus camaldulensis) measured 111 feet high, with a trunk circumference of 267 inches and a crown spread of 130 feet when it was nominated in 2014. The karri gum (Eucalyptus diversicolor), nominated in 2007, measured 154 feet high, with a trunk circumference of 201 inches and a crown spread of 74 feet.

The California Register of Big Trees is a program of Cal Fire and Cal Poly that maintains records for the largest specimen of each native and naturalized tree species growing in the Golden State. The register seeks to recognize and sustain these living landmarks. California has 210 Big Tree listings, including 121 national champions and 33 co-champions.

As a Tree Campus USA, Cal Poly continues to meet the Arbor Day Foundation’s five standards, which include maintaining a tree advisory committee, a campus tree-care plan, dedicated annual expenditures for its campus tree program, an Arbor Day observance, and a student service-learning project.

About the Arbor Day Foundation
The Arbor Day Foundation is a million-member nonprofit conservation and education organization that seeks to inspire people to plant, nurture and celebrate trees. To learn more, visit

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