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Emory oak near Young, Arizona © Nanebah Lyndon
Emory oak acorns are a critically important commodity for...
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Plant Focus

Quercus texana New Madrid acorn
Disentangling the cultivar published as Quercus texana ‘New Madrid’

The Oaks of Silicon Valley from the 1850s to Today

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Erica Spotswood, Robin Grossinger, Steve Hagerty, Erin Beller, April Robinson, and Letitia Grenier

Published May 2019 in International Oaks No. 30: 85–92


Many cities in California have been established in areas that were historically dominated by native oaks. In these landscapes, dramatic transformation has often occurred, leading to the replacement of native oaks with many non-native trees. While these transformations are well known, relatively few efforts have been made to quantify the extent of change. Here, we draw on historical and contemporary datasets from the cities in what is known today as Silicon Valley to compare the composition and structure of the modern urban forest to the historical landscape. We show that there have been dramatic shifts in forest structure and composition, including large increases in the species richness of trees, a near total loss of understory herbaceous vegetation, and a loss of large trees. These changes suggest that a reintroduction of native oaks could help to increase the ecological functions of the urban forest.


California oaks, historical ecology, urban forestry, Quercus lobata, Quercus agrifolia


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Beller, E., A. Robinson, R. Grossinger, and L. Grenier. 2015. Landscape Resilience Framework: Operationalizing ecological resilience at the landscape scale. SFEI Publication #752. Richmond, CA: San Francisco Estuary Institute-Aquatic Science Center. 

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Jackson, R.D., and J.W. Bartolome. 2007. Grazing ecology of California grasslands. In California Grasslands: Ecology and Management, edited by M.R. Stromberg, J.D. Corbin, and C.M. D’Antonio, pp. 197-206. Berkeley: University of California Press. 

Keeley, J.E. 2002. Native American impacts on fire regimes of the California coastal ranges. Journal of Biogeography 29: 303-320.

Kenderdine, T.S. 1898. California revisited. 1858-1897. Newtown, PA: Doylestown Publishing.

Mensing, S. 2015. The Paleohistory of California Oaks. In Proceedings of the Seventh California Oak Symposium: Managing Oak Woodlands in a Dynamic World. General Technical Report PSS-GTR-251, coordinated by R.B. Standiford and K.L Purcell, pp. 34-47. Berkeley, CA: U.S. Department of Agriculture Forest Service, Pacific Southwest Research Station.

Minnich, R.A. 2008. California’s Fading Wildflowers: Lost Legacy and Biological Invasions. Berkeley: University of California Press.

Powell, D.C. 2008. Using General Land Office Survey Notes to Characterize Historical Vegetation Conditions for the Umatilla National Forest. White paper F14-SO-WP-SILV-41. U.S. Department of Agriculture Forest Service, Pacific Northwest Region, Umatilla National Forest.

Simpson, J.R., and E.G. McPherson. 2007. San Francisco Bay Area State of the Urban Forest Final Report. Davis, CA: U.S. Department of Agriculture Forest Service, Pacific Southwest Research Station, Center for Urban Forest Research.

Spotswood, E.N., Grossinger, R.M., Hagerty, S., Beller, E.E., Grenier, J.L., Askevold, R.A. 2017. Re-oaking Silicon Valley: Building Vibrant Cities with Nature. SFEI Report # 825. Richmond, CA: San Francisco Estuary Institute. 

Whipple, A.A., R.M. Grossinger, and F.W. Davis. 2011. Shifting baselines in a California oak savanna: nineteenth century data to inform restoration scenarios. Restoration Ecology 19(101): 88-101.

White, A.S. 1976. Evaluating Land Survey Notes to Determine the Pre-Settlement Structure of the Lubrecht Forest, Montana. Masters thesis, University of Montana. UMI # EP41144.