Tony Gurnoe, San Diego Botanic Garden
A small disjunct population of Quercus cedrosensis just north of the border faces a barrage of threats, from wildfire and drought to succumbing to bulldozer blades as part of the border wall construction. Recognizing the immediacy of the need, especially given the lack of even a single ex-situ specimen known anywhere from the U.S., the San Diego Botanic Garden (SDBG) designed a conservation plan in collaboration with more than a dozen partners including other botanical gardens, state and federal agencies, the Global Conservation Consortium for Oaks, and the Center for Plant Conservation to work to save this little-known species. SDBG’s staff initiated a comprehensive survey of the rugged Otay Mountain Wilderness where these scrubby oaks grow to finally gain a solid understanding of the extent of the range of this species in the U.S. and how many individuals the population consists of. This facilitates a conservation collection containing the most robust genetic representation of every occurrence possible to provide a sustainable safeguard. However, after many unfruitful years of monitoring these oaks for mature acorns, this year’s poor rain season does not seem a promising indicator for the few acorns that currently hang on the trees. Although SDBG’s team still aims to collect acorns along maternal lines to be grown and distributed to living collections at partnering institutions, contingency plans have been enacted involving vegetative propagation of these rare plants via both traditional cuttings and layers as well as tissue culture. It will take years before we confidently have ex-situ living trees displayed in the landscape of SDBG and our partnering public gardens so we will continue to work toward both in-situ and ex-situ conservation of this and other rare species in our region through every available avenue.