Three years of drought are taking their toll on Southern Oregon forests now dotted with dead and dying trees hit hard by lack of water or by insects in seemingly worse fashion than in past droughts, and the death likely will continue.
The dead trees are primarily Douglas firs that are showing their vulnerability, while even some of the more drought-tolerant trees such as Ponderosa pines have lost in the competition for water in denser stands, experts say.
The burnt-orange stain of dead conifers plagues forests from the Applegate Valley up the West Cascades into the Willamette Valley, and the levels are even worse than the die-offs in the mid-1990s and early 2000s caused by drought years that were less severe than recent episodes.
"It's quite striking," says Ellen Goheen, a plant pathologist with the Rogue River-Siskiyou National Forest. "I never remember seeing it quite this dramatic in the 22 years I've been here."
The die-offs come despite a wet winter, because the dearth of water and associated attacks on stressed trees from beetles date back to the winter of 2013 and the ensuing two drought years, with many of the trees' fates already cast before this past winter.
"It's a hand playing out that we probably thought would be played out when we looked around two or three years ago," says Oregon Department of Forestry spokesman Brian Ballou in Central Point. "We just didn't know what it would look like."
Private landowners are peppering ODF with calls for advice on how to save their dying trees or find ways to remove the dead ones.
"There are a lot of folks worried about this and having issues with this," says Matthew Krunglevich, an ODF district protection planner working with landowners here. "There is destined to be stuff scattered everywhere."
While most reports so far are anecdotal, the scale of the die-off will be quantified next month during aerial mapping surveys, which the Forest Service and ODF have done jointly since the late 1940s. Last year's map can be found online here.
Drought hits different trees in different locations in different ways. Pines, oaks and madrone do better than Douglas firs, which here are along the eastern edge of their range, experts say.
South-facing slopes and areas with dry soils contain more drought-killed trees, and dense stands where trees are in competition with each other also sport more mortalities, Goheen says.
"They're struggling against each other for water, and some are better at getting water than others," Goheen says.
"Some of the smaller trees are flat-out dying for a lack of water," she says.
Others take more time.
Pests such as the flat-headed fir borer and several species of pine bark beetles attack trees stressed by lack of water and overcome them over time. Typically the pests eat away at the trees' cambium layer, cutting off the trees' ability to funnel moisture up their trunks.
"The tree dies from the top down," Krunglevich says.
Owners of private forestland need to stay on top of how their trees are faring, either by hiring a forest contractor or calling ODF for consultation, Krunglevich says.
Many landowners will see pines oozing pitch, and that shows they are fighting bug infestations in a process called "pitching out," he says.
Dead pines, however, need to be cut down and cut into pieces no larger than three inches in diameter to keep the bugs in the tree from infesting others, Krunglevich says. Doing so physically disrupts their reproductive cycle by removing needed space, he says.
"If not, you're just making a buffet for more bugs," he says.
Douglas firs generally don't keep insect colonies alive, and dead ones often can be felled and left on the ground, Krunglevich says.
If the tree is still alive, don't bother trying to water it, he says. Clear brush and other water-robbing plants away from it to give the tree a fighting chance on its own, he says.
"We'll continue to see this for two or three years before they climax and come back to a more manageable level," Krunglevich says.
"What you're witnessing is Mother Nature in place," he says. "It's part of what we live with in the natural environment."