Managed fire in a California oak woodland. Photo by Lee Klinger.
A recent study reported at Science Daily on the fire history of post oaks in Illinois reads like page from the history of California oak woodlands:
Old-Growth Tree Stumps Tell the Story of Fire in the Upper Midwest
The new study, in the journal Castanea, confirms that the people who lived in Illinois before European settlers arrived [Native Americans] were in the habit of setting fires in the region nearly every year, with fires in the Hamilton County woodland occurring at least every two or three years, McClain said. This repeated burning actually stabilized the prairies and open woodlands that dominated the region until the late 19th century, when the fire-suppression efforts of the new settlers allowed different plant species to take over, the researchers said.
The study was conducted by William McClain, a botanist with the Illinois State Museum along with researchers John Ebinger and Greg Spyreas, of the Illinois Natural History Survey at the University of Illinois. They also report:
“For hundreds, maybe thousands of years, this was a stable post oak woodland,” Spyreas said. “And then you have a gap of a couple of decades where there were no fires and suddenly the whole system is completely different. It’s amazing how, from Kansas to Ohio, these ecosystems completely depend on fire to be stable.”
See the full report here.
To all you Californian’s concerned about the oaks, this study is highly relevant.
Sudden Oak Life 
“Because of fire exclusion there are now more bay laurels than ever in the San Francisco Bay Area, and this targeted approach is not going to have an ecologically negative impact on coastal forests,” said Garbelotto, the head of UC Berkeley’s Forest Pathology and Mycology Laboratory. “On the contrary, by preserving oaks, the plan will actually protect the wildlife and the beneficial microbes that are associated with oaks, and that are normally not found associated with bay laurels.”
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2011/07/13/BAMR1K98CL.DTL#ixzz1S4YcFNdg
Thanks for alerting me to this article Ralph. See my recent post “On managing California bay laurels to improve oak health” for comments and recommendations.
The larger question is do you think that this disease is native and has propagated on bays due to lack of fire which allowed bay trees to proliferate and outnumber oak trees.
The tightly knit ecology between Phytophthora ramorum, bay laurels, and oaks, the multiple P. ramorum “parent” populations, the hundreds of P. ramorum variants, and the opinion of Phytophthora expert Dr. Michael Coffey, all lead me to believe that P. ramorum is more likely to be native than exotic.