Foresters plan for another beetle invasion<br>
Around 45 people from around Williams listen to John Anhold, a forest health expert with the Forest Service, while he shows the extent of bark beetle infestation statewide.
The number of trees killed by beetle attacks in the Williams and Tusayan ranger districts has more than quadrupled from this time last year, Herron said.
And things will likely get worse before they get better.
“We’re going to see more dead trees initially,” said Herron.
Forest officials point at the ongoing drought and previous fire-prevention policies as reasons why the forests are now so susceptible to the beetles.
“There are too many trees out there now and they’re competing for water,” Herron said.
Area forests are more densely populated with trees than they were more than 100 years ago, he said.
Bark beetles generally attack areas where trees were weakened by construction or lightning damage or have suffered prolonged drought stress.
Trees usually have natural defenses to fend off beetle attacks, but years of drought conditions have taken much of that away. Usually trees are able to pitch out beetles by secreting sap that flushes the burrowing insects out the same way they came in. But without moisture, most trees are now producing far less pitch than normal.
Once a beetle finds a tree to attack, it uses pheromones to summon reinforcements.
“The smell tells other beetles hey, come help me kill this tree,” said Tom DeGomez, a forest health specialist from the University of Arizona, in Tucson.
Getting rid of trees that have already been attacked is one important thing property owners can do to protect their remaining trees.
“If it’s brown, cut it down,” DeGomez said. “If in doubt, cut it out.”
Currently, beetles are hibernating in trees they’ve already attacked. That will change in the next few weeks, however. Beetles in the Kaibab area are expected to take flight in the next few weeks and will be seeking new trees to attack and lay eggs.
The beetles’ fast reproductive cycle makes them extremely difficult to contain, said John Anhold, a forest health expert with the Forest Service.
The beetles are a natural part of the forests’ ecosystems. From 1993 until last year, beetle infestations generally killed no more than 50,000 acres, Anhold said.
Anhold called the estimate of two million dead trees conservative. That number could be as high as six million, he said.
Williams Ranger District officials are currently removing dead trees in high-value areas, such as campgrounds, but the high costs and saturated local timber markets make it a difficult task, Herron said.
“We’re not taking out all the dead trees out there,” he said.
Instead, the Forest Service is concentrating on thinning out the forests to give remaining trees a better chance at defending themselves.
When too many trees compete for water, they all suffer, officials said. Trees left in thinned-out forests should be able to grow stronger and protect themselves against attacking beetles, officials say.
“A weakened tree is a much better host than a healthy tree,” DeGomez said.
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