In the second study, published online in the journal Oecologia, Ferrenberg, Mitton and Jeffrey Kane, of Humboldt State University in California, found that a second physical characteristic of a tree also helps predict how resistant the pine is to beetle infestation.
The team discovered that trees that had survived beetle attacks had more resin ducts than trees that were killed. The number of resin ducts differed between trees of the same age, and in general, younger trees had more resin ducts than older trees.
The number of resin ductswhich is related to the trees' ability to pitch out the beetlesis easily counted by taking a small core of the tree.
"There are very practical applications," Ferrenberg said. "These two traits are very easy to see on the tree."
Because young trees tend to have smoother bark as well as more resin ducts, the research also suggests that land managers should consider cutting down some older trees when mitigating properties to resist beetles.
"This contradicts the approach that has been historically common for fire management," Ferrenberg said. "The common approach for fire is to cut all the small trees. But if you want to defend a small amount of land against bark beetles, that may not be the best strategy."
|Contact: Scott Ferrenberg|
University of Colorado at Boulder