The Bounty of Tanoaks
In our corner of California, the tanoak tree (Notholithocarpus densiflorus) provides much of this bounty. Tanoak acorns are uniquely suited to meeting people’s needs. Tanoak acorns have a thicker shell than most other species which makes them more resistant to fungi and insects. A properly stored tanoak acorn can last for years which makes them the perfect food for lean winter months. In fact, tanoak acorns were the basis of the pre-colonization Northwest California economy. Oral histories and firsthand accounts tell us that the Karuk regularly traded tanoak acorns for white deer skins, obsidian, dentalia shells, and sugar pine nuts with neighboring tribes. Indigenous Peoples of California also use the tanoak acorn for medicinal purposes. For example, the tannins in the acorn have cough suppressant properties and among the Kashaya Pomo the acorns are used as a natural cough drop.
A mature tanoak can produce as much as 200 pounds of acorns per year with estimates for the most productive old growth trees ranging as high as 1000 pounds. Indigenous Californians used fire to manipulate vegetation in order to maximize acorn production. Many old-growth tanoak groves today are the result of meticulous planning by Indigenous Californians hundreds of years ago. Tanoak acorns are also a staple for animals native to Northwest California. Many tribes have long chosen to halt the acorn harvest towards the end of November, preferring to leave enough acorns to support the other species with whom they share the land. Modern researchers have studied how tanoak acorns provide an irreplaceable food source to many species and that without them our forest ecosystems would be severely threatened.
As Europeans colonized Northwest California, they made a great effort to disrupt Indigenous food practices. Most directly, European Americans used violence to drive Indigenous Californians away from the best places to harvest acorns. But a more subtle kind of disruption also occurred. To European Americans, acorns were only good for hog fodder. And tanoak trees were more valuable after being cut down and used to tan leather. As the timber industry developed, the value of tanoak in the eyes of the European Americans degraded even further and it became commonly referred to as a “trash tree”. Government foresters and private landowners regularly employed (and continue to employ) herbicide in order to prevent these trees from taking up space that could be used by more economically valuable softwoods. Despite these challenges, tanoak remains a culturally significant tree to Indigenous Californians. Actively resisting assimilation, tribal members have continued to harvest acorns even when threatened with violence by European Americans for doing so. Many tribes continue to celebrate the harvesting of acorns with an annual acorn feast.
Tanoak tree killed by Sudden Oak Death (Phytophthora ramorum) in southwest Oregon.
Today, a new invasive threat endangers tanoak. The disease Sudden Oak Death (SOD) was first identified in the Bay Area in 1994. Researches noticed that some tanoaks were developing cankers which bled profusely before eventually killing the tree. SOD is caused by the pathogen Phytopthora ramorum which researchers believe originated in Asia. The disease obstructs a tree’s xylem cells and reduces their water supply until eventually killing its host. Since its arrival in California, it is estimated that SOD has killed more than 38 million tanoak trees and wreaked havoc on other oak species as well.
California has convened an Oak Mortality Taskforce to work on solutions to the threat. Their website www.suddenoakdeath.org/ contains information about how to spot SOD and how to make sure you don’t accidentally spread it. Hopefully, we can stop the spread of this disease and finally listen to Indigenous Californians about the value of this giving tree.