Sudden Oak Death Transforming California - Sacramento Bee

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"California's oaks are dying. Not all of them - and not the ones around Sacramento, but enough to raise questions about whether the Golden State's ecology is about to be wildly altered.

The problem is a blight called sudden oak death, which started cropping up in 1995 and has since killed tens of thousands of trees, mostly in the coastal mountains between Big Sur and northern Sonoma County. In places, the blight is so extensive that entire hillsides have been devastated, says David Rizzo, a plant pathologist at the University of California, Davis. The disease has also shown up in nursery trees shipped to at least 17 other states and in Europe, raising concerns that it may rapidly spread across the globe.

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Prior studies had found that Phytophthora infected from 4 percent to 30 percent of the coast live oak in any given patch, and from 20 percent to 70 percent of tanoak. But Brown found that up to 27 percent of the coast live oak within her study plots died in the two-year interval from 2002 to '04. (Her research focused only on coast live oak, and not the even-more-susceptible tanoak.) If you add in recently dead trees that were probably killed by sudden oak death, plus living trees showing symptoms of Phytophthora infection, the death rate in her most heavily infected plots may soon exceed 60 percent. And that's not counting any still-healthy trees that might yet succumb to the disease.

Ecologically, the death of that many oaks is an immense change to California's coastal woodlands. To start with, all of that dead wood will provide fuel for potentially intense fires. In addition, sick, dead and dying trees open the door for the spread of other diseases. That's already happening in some areas, where Rizzo says that a native pathogen, oak root fungus, is already taking hold. This doesn't mean that California's coastal woodlands are on the verge of turning into deserts. Eventually, some other species will move into the gaps - most likely California bay laurel, Brown says. Unfortunately, Brown's colleague Kyle Apigian, also of UC Berkeley, says that this may be bad news for birds. Such species as oak titmice and chestnut-backed chickadees, which forage heavily on coast live oak, keep away from bay laurels, Apigian reported."

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http://www.sacbee.com/content/opinion/story/10386808p-11306482c.html