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On May 30, 2024, a rare demonstration of cork oak harvesting took place in the shade of the UC Davis Arboretum’s 80-plus-year-old cork oak grove. This traditional process, unknown to most Americans, involves carefully removing the outer bark of a cork oak tree without damaging the tree. The demonstration, which is usually performed by skilled artisans in Portugal and Spain, was organized for students in the Technology and Viticulture Systems course (VEN 135), representatives of the regional wine industry, and various campus members.

Organized by Cork supplyThe UC Davis Department of Viticulture and Enologyand that UC Davis Arboretum and Public GardenThe program provided participants with a unique learning experience and educational outcomes that extended beyond the event itself.


“Cork is very important to our students,” said David Block, professor of viticulture and enology. “Having the opportunity to watch the cork harvest here is truly a once-in-a-lifetime experience. I’m very happy that we were able to do this.”

For the UC Davis Arboretum and Public Garden, the event demonstrated how managing the campus environment as a living museum provides numerous educational opportunities for students and the community. “Our strategic initiative, UC Davis GATEways Projectconnects our gardens and landscapes to the university’s academic mission. This cork oak harvest is a perfect example of that commitment,” said Kathleen Socolofsky, associate vice chancellor and director of the UC Davis Arboretum and Public Garden.

Campus Oak Connection

The UC Davis campus has a long history with oak trees. Of the more than 25,000 trees that the Arboretum and Public Garden care for, over 6,000 are oaks, and 532 of them are cork oaks. Much of the campus’s incredible cork oak stand was planted during World War II to address a national cork shortage. Today, cork oaks are one of 109 species of oak that thrive at UC Davis. The diverse collection is now nationally accredited by the American Public Gardens Association Network of Plant Collections.

“We thought long and hard about the possibility of stripping the bark from a historic cork oak, but the decision was easier knowing that we would be working with the best people in the world at the right time of year,” said Emily Griswold, director of GATEways Horticultural and Teaching Gardens at the UC Davis Arboretum and Public Garden. “It’s an important use of our collections to use them for educational purposes in this way.”

About the harvest

Two professional cork harvesters from Portugal demonstrated the process of peeling the tree bark to about 100 visitors. Throughout the exhibition, Greg Hirson, Global Director of Innovation for Cork Supply and a UC Davis graduate in viticulture and enology, answered questions and interpreted the experts’ work in real time.

Similar to the harvest in their home country, the team worked in pairs and removed the tree’s outer cork bark using only hand axes. The delicate work of these experts is not for nothing considered one of the best-paid agricultural jobs in the world and is done without any automation between mid-May and the end of August – the active growth period of cork oaks and the main reason why harvesting does not damage the tree’s health.

When one of the cork panels was removed, the audience was shown the layer of moisture that covered the “belly” of the bark. This sign confirmed that the selected oak was at the right stage for harvesting.

Learn about the traditional practice of sustainable cork harvesting. (Jael Mackendorf/UC Davis)

Cork as a renewable raw material

“Each cut must be done carefully so that the tree remains healthy and can continue to produce cork,” says Frederico Mayer, purchasing manager at Cork Supply. “The first harvest of a cork tree is not suitable for the production of fine cork products such as wine stoppers. It is only the third harvest of a cork oak, 18 years after the first, that you get a bark that tastes almost like vanilla ice cream.”

Due to their unique genetic makeup, cork oaks grow a thin layer of bark each year. After the bark is removed, it takes about 9 years for the trees’ bark to grow thick enough to be harvested again. Over the course of a cork oak’s 150 to 200 year lifespan, a single tree can be harvested up to 15 times, illustrating cork as a renewable resource.

“There is a misconception that trees are cut down to make cork,” said Anna Brittain, CEO of Napa Greena non-profit organization that provides sustainability and climate certifications for vineyards and wineries. “Cork is indisputably the most sustainable closure… and climate positive.”

future plans

Could another harvest be planned in the future? “It’s possible,” said Griswold. “In the meantime, we hope that all visit this tree In the coming years we will witness the change in the colour and texture of the bark as it regenerates.”

Temporary signage is now attached to the felled tree explaining its surprising appearance. Plans for permanent signage are in the pipeline. UC Davis academics interested in obtaining pieces of the harvested cork for teaching or research purposes are encouraged to Contact the Arboretum and Public Garden for more informations.

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