Climate Change and the Management of California Oaks in the Urban Environment

Igor Lacan, Bay Area Environmental Horticulture and Urban Forestry Advisor, UC Cooperative Extension, San Mateo-San Francisco Counties

Adapting urban tree populations to the changing climate has become a ubiquitous goal of urban tree managers.  In California cities, this process is complicated by the variety of oaks that have been planted in cities (with variable success), as well as by the diversity of urban tree habitats, many of which are hostile to trees when combined with our dry-summer climate.

I will review the methods that have been proposed for evaluating urban trees’ adaptability to the changing climate.  I will then focus on the “space for time substitution” that Joe McBride and I used to assess the common street trees across California cities, demonstrate the method and discuss the results. 

I will also review the newly-available on-line data sources (the California Urban Forest Inventory project from Cal Poly San Luis Obispo), and what we can learn about urban oaks in California from urban tree inventories.  I will conclude by discussing the recent interest in “new” (to city landscapes) oak species, and the issue of water availability as a long-term challenge to urban oaks in California.