EPOW - Ecology Picture of the Week

Blue Oak (Quercus douglasii) Woodland
Central Valley, California

Explanation:  Why are these trees sad?  For one reason, they are Blue Oaks (Quercus douglasii).  For another reason, they are not regenerating.

Blue oak trees are adapted to persist and thrive in drought and Mediterranean climates with hot dry summers.  

Ringing much of the Central Valley of California along lower elevation slopes is the Blue Oak - Digger Pine Woodland.  Actually quite widespread, this woodland type has been undergoing some radical change.  The oaks are not regenerating.  The cause?  It's probably a combination of habitat conversion, livestock grazing and trampling, and cessation of ground fires that used to frequent this environment before people began viewing fire as evil.  

Is there any good news here?  Yes ... only that "sudden oak death" (SOD) -- caused by a fungus-like organism (a protist) -- does not yet appear to be a major source of mortality for blue oaks, although it is hitting 5 other of the 8 total species of oak that occur in California.