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Ancient tribal communities across the state have relied on acorns as a staple of their diet, and in some parts of Southern California acorns constituted the majority of the ancient diet. It is no surprise that oaks occupy a special place in the culture of tribal communities.

Oaks in Southern California are under incredible stress and oak woodlands are a threatened and declining plant community. Southern California hosts a variety of oak trees including the rare Engelmann oak, (Quercus engelmanii). Suburban and ex-urban development threaten these plant communities as fragmentation is increasing in natural areas. 

In addition, the epicenter of the goldspotted oak borer (GSOB, Agrilus auroguttatus) infestation is in San Diego county. In severely impacted areas oak mortality from GSOB infestation has exceeded 95%, with nearly 75% loss in canopy cover in infested areas. New GSOB infestations have been found moving north in Southern California in the San Gabriel and San Bernardino Mountains. On top of these threats, another pair of new tree pests, two invasive shot hole borers (ISHB, consisting of the polyphagus shot hole borer and the Kuroshio shot hole borer, Euwallacea spp.) are found in San Diego County and are damaging oak woodlands.

Furthermore, the long-term drought from 2012 to 2016 caused a decline in the production of seedlings in the oak woodland community. All in all, oak canopies in Southern California are declining. Until these pests are successfully controlled, the best method we have to prevent dramatic losses in oak woodlands are to widely plant acorns and seedlings.

Oaks are a meaningful and important part of tribal culture and are a crucial component of woodlands in Southern California. UCCE is committed to working with indigenous communities to assist in preserving, restoring and protecting our shared natural resources.

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For more information about the Southern California Partnership for Restoring Oaks on Tribal Lands, contact:

Chris McDonald 
UCANR Natural Resources Advisor 


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