Beetles and Fungus Ravaging Calif. Oaks
Discovery Earth Alert, Dec. 16, 1999
Foresters in California are alarmed over 30,000 coast live oak and tan oak trees that have been destroyed by beetles and a predatory fungus in the past few years. Oaks, the state's most common trees, are an emblem of California and are valued for the picturesque landscapes they create. Researchers believe that the trees have been weakened by the droughts of the mid-`80s and early `90s, followed by heavy El Nino rains in 1997 and 1998. The oaks' distressed state has made them susceptible to a fungus that in turn, lures bark beetles to the trees. The hypoxlyon fungus takes hold of the trees' soggy roots. Sensing a feast, the female bark beetle bores into the tree. Once there, she sends out a phermone call to other beetles, said Larry Cooper, spokesman for the state Department of Food and Agriculture. The beetles then attack the tree until it's dead, Cooper said.
Teamed up, the beetles and fungus can kill a tree in two weeks. "I'm sure it's part of the natural scheme of things, but there's no historical record of this occurring before,'' said Bruce Hagen, an urban forester with the California Department of Forestry. ''It's really a strange and kind of unexplained phenomenon at this time." The oaks can live for 250 to 300 years, and are mostly found on private land. More than 300 species of animals and more than 5,000 insects make a home out of the habitats provided by the trees, said Bill Tietje, a natural resources specialist with the University of California.