On May 30, 2024, under the shade of the 69成人 Arboretum鈥檚 80-plus-year-old cork oak grove, a rarely seen exhibition of cork harvesting took place. This traditional practice, unfamiliar to most Americans, involves the careful stripping of a cork oak鈥檚 outer bark without harming the tree. Commonly performed by skilled craftspeople in Portugal and Spain, the demonstration was organized for students in the 鈥淭echnology and Winery Systems鈥 (VEN 135) class, regional wine industry stakeholders, and various campus affiliates.
Arranged by , the , and the , the program provided a unique learning experience for attendees and educational outcomes extending beyond the event itself.
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鈥淐ork is a very important to our students,鈥 said David Block, professor of viticulture and enology. 鈥淗aving the opportunity to see the cork trees harvested right here, is really a unique experience. I am very happy that we were able to do this.鈥
For the 69成人 Arboretum and Public Garden, the event highlighted how managing the campus environment as a living museum supports multiple educational opportunities for students and the community. 鈥淥ur strategic initiative, the , connects our gardens and landscapes with the university's academic mission. This cork oak harvest is a perfect example of that commitment," said Kathleen Socolofsky, assistant vice chancellor and director of the 69成人 Arboretum and Public Garden.
Campus oak connection
The 69成人 campus boasts a rich history with oaks. Of the 25,000-plus trees in the Arboretum and Public Garden鈥檚 care, over 6,000 are oaks and 532 of those are cork oaks. Much of the campus鈥檚 incredible cork oak inventory was planted during World War II to address a national cork shortage. Today, cork oaks are one of the 109 kinds of oaks thriving at 69成人. The diverse collection is now nationally accredited through the American Public Gardens Association .
鈥淲e thought long and hard about the prospect of bark being removed from a heritage cork oak, but the decision became easier knowing we'd be working with the best people in the world, at the right time of year,鈥 said Emily Griswold, director of GATEways horticulture and teaching gardens at the 69成人 Arboretum and Public Garden. 鈥淚t's an important use of our collections to see them used for educational purposes in this way."
![Carlos Ferreira (left) and Joao Ferreira (right), skilled craftspeople from Portugal, demonstrate the process of cork harvesting by stripping the bark of a cork oak treeas students in the 鈥淭echnology and Winery Systems鈥 class, regional wine industry stakeholders, and various campus affiliates look on. (Gregory Urguiaga/69成人)](/sites/default/files/styles/sf_large_width/public/media/images/20240530-cork-harvest-4513%20%281%29.jpg?itok=K2loYbQb)
![Bark from a cork oak tree after harvest. (Gregory Urquiaga/69成人)](/sites/default/files/styles/sf_large_width/public/media/images/20240530-cork-harvest-4409.jpg?itok=FzyMxncp)
About the harvest
Two professional cork harvesters from Portugal demonstrated the process of stripping the tree鈥檚 bark for approximately 100 attendees. Throughout the exhibition, Greg Hirson, global director innovation for Cork Supply and 69成人 Viticulture and Enology alumni, answered questions and interpreted the activity of the experts in real time.
Similar to how a harvest happens in their home country, the team worked as a pair, relying solely on hand-axes to remove the tree鈥檚 outer layer of cork bark. Documented as one of the highest-paid agricultural jobs in the world for good reason, the delicate work of these experts is done without any automation between mid-May and the end of August 鈥 the active growing season for cork oaks, and the main reason why the harvest does not damage the tree鈥檚 health.
Upon removal of one of the sheets of cork, the audience was shown the layer of moisture coating the "belly" of the bark. This sign confirmed that the selected oak was in the right stage for harvesting.
Cork as a renewable resource
"Each cut must be made with care to ensure the tree remains healthy and can continue to produce cork,鈥 said Frederico Mayer, purchasing director for Cork Supply. 鈥淎 cork tree鈥檚 first harvest is not suitable for producing fine cork products like wine closures. It鈥檚 not until a cork oak鈥檚 third harvest, 18 years after the first, that you get bark that鈥檚 almost like vanilla ice cream.鈥
Cork oaks grow a thin layer of bark every year as a result of their unique genetic makeup. Post bark removal, the trees take about 9 years for their bark to become thick enough to harvest again. Over the course of a cork oak鈥檚 150 to 200-year lifespan, a single tree can be harvested upwards of 15 times, exemplifying cork as a renewable resource.
鈥淭here鈥檚 a misunderstanding that trees get cut down to make cork,鈥 said Anna Brittain, executive director of , a non-profit that performs sustainability and climate-action certifications for vineyards and wineries. 鈥淐ork is inarguably the most sustainable closure鈥nd climate positive.鈥
Future plans
Could another harvest be planned in the future? 鈥淚t is possible,鈥 said Griswold. 鈥淚n the meantime, we hope everyone over the coming years to witness the transformation of the bark鈥檚 color and texture as it regenerates.鈥
Temporary signage is now on display by the harvested tree to explain its surprising appearance, with plans for permanent interpretive signage in development. 69成人 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 information.
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Media Contact:
- Amy Quinton, News and Media Relations, 530-601-8077, amquinton@ucdavis.edu