California Oaks Underground

Angela Moskow

Published May 2026 in International Oaks No. 37: 225–232

Abstract

California’s native oak ecosystems are supported by a large diversity of fungi that have evolved independently many times, with many different structural and physiological characteristics. Research has explored the vital interrelationship of mycorrhizal fungi and California’s native oak communities, including carbon sequestration, mycorrhizal connections to water supplies, above- and belowground biodiversity, and Indigenous community practices in tending beneficial fungi in many areas of the state. California Wildlife Foundation’s California Oaks program issued a report in 2024 that provides an overview of these biological and cultural relationships, as part of our work to make the case to keep native California oaks standing. This report draws on research by Michael F. Allen (Professor Emeritus at the University of California, Riverside) about the interrelationships between oak mycorrhizal soil-carbon storage and hydrology. It also shares ethnographic research findings by M. Kat Anderson, PhD, and Frank K. Lake, PhD, about the use, harvest strategies, and management of different species of fungi by the Indigenous tribes of California. This report was issued as part of a series of publications by the California Oaks program that demonstrate the importance of oaks for the state’s imperiled Indigenous cultures and natural ecosystems. California’s oak ecosystems and the species they support are at risk unless the state enacts and enforces measures to ensure no net loss of oaks.

Keywords

fungi, mycorrhizae, Notholithocarpus, Quercus

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