Ex-Situ Conservation of Six Oak Species at San Diego Zoo Wildlife Alliance

Dario Berrini, Greg Bluffin, and Christy Powell

Published May 2026 in International Oaks No. 37: 295–302

Abstract

This paper illustrates the most recent endeavors by San Diego Zoo Wildlife Alliance (SDZWA) and its partners to create ex-situ collections of several rare and endangered oaks, focusing primarily on Quercus cedrosensis and Q. dumosa. Threats like habitat loss and fragmentation, fire, climate change, and border activities are creating enormous pressure on many plant species, and oaks are no exception. Propagating these oaks begins with a range of activities in the field including ArcGIS mapping, collecting leaves for DNA analysis, new growth for micropropagation work, pollen and, of course, acorns. We collect and track multiple maternal lines to ensure genetic diversity as the ex-situ collection grows. Finding viable acorns, however, has proven to be quite challenging for some species, particularly, Q. cedrosensis. This has led us to try other propagation techniques such as cuttings, air layering, micropropagation and, in one case, an in-situ oak rescue. All these propagation methods have proven successful to various degrees and have resulted in the planting of several young oaks as the start of ex-situ oak collections. We are planting oak groves at the Zoo and Safari Park and sharing seedlings with other institutions through the Global Conservation Consortium for Oak (GCCO).

Keywords

Quercus, engelmannii, dumosa, pacifica, tomentella, parvula, cedrosensis, acorns, propagation, cryogenic

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