Tanoak (Notholithocarpus densiflorus) grows in coastal forests in Oregon and California and plays an important ecological role in the redwood forest ecosystem. Its medium-height trees add a second canopy to the complex architecture of an old-growth redwood forest, creating more niches for diverse species. And its nutritious acorns feed bears, deer, rodents and birds.

For now, tanoak is still abundant. But where redwood forests show signs of the emerging disease called “sudden oak death,” the species has been decimated. Kevin L. O’Hara, University of California, Berkeley, silviculture professor and PhD candidate Ben Ramage are studying what happens to redwood ecosystems in places where tanoaks have disappeared.

In a 2008 study funded by Save the Redwoods League, O’Hara and Ramage documented numerous changes caused by tanoak’s demise—among them more sunlight, deadwood and herbaceous species on the forest floor. The study’s most important finding, however, had to do with the forests’ inability to regenerate trees of any kind. “If a tanoak clump dies and it leaves an opening in the forest, we’re not seeing any new trees come into that opening,” O’Hara said.

The tanoak tree is an important species in maintaining the biodiversity of plants, animals, and fungi within an ecosystem.

(Excerpt from Ramage, B. and Ohara, K. from Save the Redwoods League Project, 2008.)