Bark beetlePosted: July 12, 2021
In years of drought, when trees in the forests of Oregon and northern California don’t get enough moisture, they don’t create the sap they need to prevent attacks of tiny bark beetles. The bark beetles kill trees, leaving the forest littered with dead trees, ideal conditions for a huge fire.
The beetle is a tiny insect, about the size of a match head, but the sheer numbers pose a risk to the forest, officials say. They lay much of the bark beetle problem on forests that have become too overgrown with small trees and brush.
And ironically, it’s decades of aggressive fire suppression that has left forests dense and overcrowded, according to the forest service.
A hundred years ago, low intensity fires regularly burned through the forests, keeping stands of trees thinned out, and prevented them from becoming too thick.
Because smaller trees were regularly thinned out by fire, the trees that remained were larger and spaced farther apart.
A hundred years ago, a forest would have typically 20 or 30 trees per acre, Hamilton said. Nowadays, though, it is not uncommon to have 800 to 1,000 smaller trees an acre, he said.
When a drought comes along, like the current one, too many trees are competing for too little moisture and the trees’ natural defense against bark beetles breaks down, he said.
When trees are healthy and they get plenty of moisture, they exude sticky sap to ward off the bugs and protect themselves.
But when trees lack water they can’t produce enough sap, and the beetles move in and damage trees until they die, Hamilton said.
“When bark beetles’ population is at epidemic levels they can still attack and overcome even healthy trees,” according to Cal Fire.
That’s from “Drought and bark beetle kill millions of trees, increase wildfire risk in North State forests” by Damon Arthur for the Redding Record Searchlight / Siskiyou Daily News.
The number of dead trees are staggering. Millions of trees:
The 2019 forest service aerial survey of tree mortality shows the Klamath National Forest, with large swaths of land in Siskiyou County, was the forest hit hardest in the state, with an estimated 1.8 million dead trees.
Here is a breakdown by county of tree mortality in the North State, according to the survey:
- Siskiyou: 2.8 million trees on 406,000 acres
- Trinity: 1 million trees on 150,000 acres
- Shasta: 305,000 trees on 115,000 acres
- Tehama: 318,000 trees on 67,000 acres
Yesterday I drove from Redmond, Oregon down here to Siskiyou County, a four hour drive, about two hours of it through smoke from a distant fire, (the Bootleg fire?), and through burnt forest, ranging from singed to totally black smoking ashscape, and still more through trees that looked dry and gnarled and unwell and ready to burn. It was over 90 degrees most of the way, dry, staying hot until 8 or 9 pm at night. A fire crew was cutting down a big old tree by the side of Highway 97, and not far beyond that was the ruins of a motel that had been burned to the ground, except for a sign, “MOTEL.”
Burnt over forest country makes me think of the start of Hemingway’s “Big Two-Hearted River”:
The train went on up the track out of sight, around one of the hills of burnt timber. Nick sat down on the bundle of canvas and bedding the baggage man had pitched out of the door of the baggage car. There was no town, nothing but the rails and the burned-over country. The thirteen saloons that had lined the one street of Seney had not left a trace. The foundations of the Mansion House hotel stuck up above the ground. The stone was chipped and split by the fire. It was all that was left of the town of Seney. Even the surface had been burned off the ground.
Nick looked at the burned-over stretch of hillside, where he had expected to find the scattered houses of the town and then walked down the railroad track to the bridge over the river. The river was there. It swirled against the log spires of the bridge. Nick looked down into the clear, brown water, colored from the pebbly bottom, and watched the trout keeping themselves steady in the current with wavering fins. As he watched them they changed their again by quick angles, only to hold steady in the fast water again. Nick watched them a long time.