Drought-stricken Oregon saw a historic spruce die-off in 2022 that left the hills once lush with green conifers dotted with clumps of red, dead trees.
The damage to the fir trees was so significant that the researchers decided to call the blighted areas “firmageddon” as they flew overhead during aerial surveys that estimated the extent of the die-off.
Surveyors eventually logged about 1.1 million acres of Oregon forest with dead spruce trees, the most damage recorded in a single season since surveys began 75 years ago.
Oregon’s dead spruce trees are a visceral example of how drought is reshaping landscapes in western states that have experienced extreme heat conditions. In many areas, in the future, these fir trees could be replaced by more drought-resistant species, reshaping the functioning of ecosystems and changing their character.
“When I looked at it and broke down the numbers, it was nearly double the acres affected than anything we’d previously documented,” said Danny DePinte, an aerial survey program manager for the United States Forest Service. United. “Nature is selecting which trees can be where during droughts.”
Oregon is known for towering volcanic domes covered in a blanket of conifers that become sparse and patchwork on the eastern side of the Cascade Mountains before entering the high desert.
People who know trees best say there are plenty of signs of trouble in Oregon.
“We are seeing stress across all of our tree species,” said Christine Buhl, a forest entomologist with the Oregon Department of Forest. “We just have to shift our expectations to what tree species we can expect to be planted where.”
Researchers have surveyed Pacific Northwest forests by air since 1947. Little about the process has changed during that time, according to Glenn Kohler, an entomologist with the Washington State Department of Natural Resources, who runs the program along with the Forestry Department and the Department of Oregon. of the Forestry.
Every summer, small, high-winged planes hover about 1,000 feet above the tree canopy at about 100 mph. Trained observers peer out from both sides of the aircraft, looking for obvious tree damage.
Dead trees — conifers solid red or orange — are the easiest to spot, but spotters can also spot trees devoid of needles in some areas.
Observers assess the extent of the damage and map its location. Pilots fly in a grid pattern with flight lines approximately 4 miles apart to cover each strip of forest.
“It’s literally like mowing the lawn,” Kohler said of the flight path.
The paper maps of the past have been replaced today by Samsung Galaxy tablets that track the aircraft’s progress and make mapping easier and arguably more accurate.
Scouts require a season of training, Kohler said. It can be a dizzying task.
“We’re scanning 16 to 30 acres per second,” DePinte said, noting that small planes can offer a more turbulent ride. “You absolutely must have a stomach of steel.”
This year, the aerial observation program flew over some 69 million acres of Washington and Oregon forest in about 246 hours.
“We are really painting the picture. It’s not hard science. You are not counting individual trees or inspecting individual trees. The scope is, what are the main trends and detect outbreaks,” Kohler said.
The extent of the damage in Oregon, which was first reported by environmental journalism nonprofit Columbia Insight, has been astounding to researchers and requires deeper study.
“We had never seen anything of this level before,” said DePinte. “He takes you back and makes you stop. Your scientific mind begins to wonder why. We don’t always have the answers.”
The trees are susceptible to bark beetles, root diseases and defoliators such as caterpillars. Aerial surveys help researchers capture the booms and busts of these pathogens.
Healthy trees can usually defend themselves against these threats. When beetles penetrate the bark of a tree, for example, a healthy tree can push the beetles out by expelling pitch, a sticky substance, where they entered the tree, Kohler said.
But disturbances like droughts, wildfires and windstorms can stress trees and weaken their defenses. Large numbers of dead and dying trees could allow bark beetles to lay eggs, feed their larvae, and thrive.
Scientists still have only a rough understanding of the factors causing widespread deaths in Oregon, but many consider drought to be the underlying culprit.
“There are multiple factors at play here. One of the things most of us agree on: The main factor we’re experiencing here is the hot drought,” Buhl said, meaning the state has been hampered by higher-than-normal temperatures and low rainfall as well.
DePinte said the damage was most pronounced in white, Shasta and spruce spruce trees on the eastern side of Cascade Mountain’s crest, where the climate is drier.
Nearly half of Oregon is experiencing severe, extreme, or exceptional drought, according to the US Drought Monitor. The drought is worst in eastern Oregon.
Average temperatures in Oregon have risen about 2.2 degrees Fahrenheit since 1895, according to a 2021 state climate assessment delivered to the state legislature. The severity of the drought has increased over the past two decades, in part due to man-made climate change, the report said. Summers in Oregon are expected to get hotter and drier.
“We have been hearing about climate change for some time. Climate change is happening. We feel it now,” Buhl said. “These summers are getting hot and long. We’re seeing evidence on the landscape. We needed to pay more attention decades ago, but we didn’t.”
Buhl said forest health impacts are clearing out roughly as many trees as fires, which are now also more likely and more intense due to climate change.
Heatwaves are also a growing threat. On Oregon’s west side, trees were scorched by the June 2021 heat dome, which drove Portland’s temperature up to 116. Scientists said the intense heat wave was “virtually impossible” without the change climate.
Aerial assessments last year documented nearly 230,000 acres of heat burns in Oregon and Washington, DePinte said. Most of the damage occurred on south-facing slopes which absorb more sunlight due to the angle of the sun in the sky.
“It was the combination of the high afternoon temperatures and the setting sun,” said Chris Still, a professor at Oregon State University’s College of Forestry. “We think a lot of those leaves are freshly baked on site.”
Still speculated that the heat dome may have also contributed to this year’s spruce deaths, but more research and evidence is needed to examine any possible connections.
DePinte said the 2021 burn was the largest on record, meaning the Pacific Northwest has seen two record-breaking damage events in its forests in as many years.
This article was originally published on NBCNews.com