Historic Plant Preservation at Frozen Zoo®
The San Diego Zoo Wildlife Alliance has achieved a groundbreaking milestone by adding its first-ever plant species to the renowned Frozen Zoo®, a significant collection dedicated to preserving living wildlife. This historic achievement showcases the innovative efforts of the organization in the realm of conservation, aiming to ensure the survival of various plant species that are under threat.
Introduction of Nuttall's Scrub Oak
On July 8, 2025, the alliance announced that samples from 18 endangered Nuttall's scrub oak trees (Quercus dumosa) have successfully undergone cryopreservation, marking the first time any plant species has been stored in the Frozen Zoo®. This initiative highlights the necessity of protecting botanical diversity, especially considering that many species, including oaks, cannot be stored in traditional seed banks due to specific biological challenges.
Christy Powell, the horticulture manager at the San Diego Zoo Wildlife Alliance, emphasized the significance of cryopreservation for the conservation of Nuttall's scrub oak. She stated, “This accomplishment represents an enormous advancement in plant conservation.
Importance of Nuttall's Scrub Oak
Nuttall's scrub oak is particularly important as it is one of the few native tree species found in San Diego County and is listed as endangered by the International Union for Conservation of Nature (IUCN). The conservation of this species does not only contribute to the preservation of plant diversity but also supports the ecosystems that depend on oaks, which are considered keystone species. Their presence sustains hundreds of wildlife species and plays a crucial role in the overall health and resilience of native habitats.
Collaborative Efforts in Conservation
The achievement was made possible through the collaboration of crucial partners such as The Huntington, Cincinnati Zoo Botanical Garden's Center for Conservation and Research of Endangered Wildlife, and the United States Department of Agriculture Agricultural Research Service's National Laboratory for Genetic Resources Preservation.
In discussing the international collaboration, Dr. Katie Heineman, an officer with the IUCN Species Survival Commission Center for Species Survival Biodiversity Biobanking, noted the broader implications of this work. “This isn't just about preserving one species—it's about providing a roadmap that others can use.”
With nearly one-third of the world’s 450 oak species at risk due to habitat loss, fire, and invasive pests, programs like that of the San Diego Zoo Wildlife Alliance are vital. Their oak conservation program works with a variety of partners, including The Nature Conservancy and San Diego Botanic Garden, to safeguard these essential trees, particularly those native to San Diego, Southern California, and Baja California.
Advancing Cryopreservation Techniques
The scientists at the San Diego Zoo Wildlife Alliance are leveraging insights gained from this initial cryopreservation to further develop techniques applicable to a wider array of native California oaks and orchids. As conservation methods evolve, the organization is expanding its cryogenic plant collection, positioning itself as a leading repository for plants that require specialized preservation approaches.
Powell remarked, “With our unparalleled cryogenic capacity alongside our world-class botanic garden, we are uniquely situated to push the boundaries of plant cryopreservation, creating a safer future for wildlife, humans, and the planet.”
About the Frozen Zoo®
Established in 1975 by Dr. Kurt Benirschke, the Frozen Zoo® serves as the world's first large-scale cryogenic biological bank focused on preserving living cells and reproductive materials from wildlife. It is the largest and most diverse collection of its type globally, housing cell lines from over 11,500 individual animals and plants representing more than 1,300 species.
Stored in liquid nitrogen at -320 degrees Fahrenheit, the collection comprises cells, embryos, and gametes from various species, including mammals, birds, reptiles, amphibians, fish, and now plants. It is an integral part of a broader initiative, the Wildlife Biodiversity Bank, which employs various strategies to safeguard biodiversity.
To learn more about the Frozen Zoo® and its groundbreaking work, visit
sdzwa.org/frozen-zoo.
About San Diego Zoo Wildlife Alliance
The San Diego Zoo Wildlife Alliance is a nonprofit organization committed to inspiring passion for nature and fostering collaboration for a healthier world. Through innovative conservation science and global partnerships, the alliance supports efforts at the San Diego Zoo and Safari Park, both recognized as leading zoological institutions and accredited botanical gardens. They have successfully reintroduced more than 44 endangered species into their native habitats and reach over 1 billion people worldwide with their conservation messaging.