PORTLAND, Ore. (CN) — The largest die-off of fir trees ever recorded in Oregon and Washington state can be blamed on climate change, according to researchers from the U.S. Forest Service, who recently observed over 1.23 million acres of affected forests between the two states.
“Climate change is happening. It's here, it's everywhere. And with that comes a different degree of effects on different areas,” said Daniel DePinte, aerial survey program manager for the service, in an interview.
According to DePinte, the areas most affected range from Central Oregon down to the California border, including the Ochoco, Fremont, Winema and Malheur national forests. But the true catalyst is the region’s ongoing drought, which has afflicted the West Coast's fishing and farming and spurred devastating forest fires.
DePinte said when drought occurs, susceptible species of firs weaken and release terpenes — plant chemicals that produce a distinct smell — which attracts opportunistic insects like bark beetles to attack and populate.
“That's the final straw that kills these trees along with some fungi also that are attacking the roots,” DePinte said. “And so, these are endemic fungi and insect bark beetles, they're always there, but what happens is when these types of droughts and climate change start to add to the stress, it basically starts to cause this big mortality event, this die-off kind of situation.”
Excluding 2020, researchers for the service have led annual surveys of the region’s forests since 1947, a process that typically notes little change. Yet, as first reported by independent journalist Nathan Gilles, the fir die-off this year is nearly double from previous years, totaling over 1.23 million acres in Oregon and Washington state — with 1.1 million acres occurring in Oregon alone.
But while "firmageddon" is limited to fir trees, not all fir species are affected the same. DePinte said the most affected species include white fir, red fir and the Shasta red fir — all of which grow in lower elevations. Higher-elevation species like the noble fir and grand fir are less affected.
Oregon’s state tree, the Douglas fir, is actually not a true fir, but the species is suffering from increased mortality, DePinte said.
Additionally, DePinte pointed out that while some of the most circulated aerial photos in news articles show nearly 50% of land areas covered in red, decaying trees, he doesn’t want people to think all of the hills look like that.
“There were some other photos in there where it showed 5% to 10% of the trees were red and dead, and then it showed that it's across the entire landscape,” DePinte said. “And that's probably more accurate.”
When asked whether the forest service could or would take conservation steps to preserve tree species, DePinte said it’s more realistic to adapt to the environment as it changes.
“We're always concerned about all of the tree species across the landscape,” DePinte said. “We want to keep up a nice level of biodiversity, and we want ideally, we would like to keep the forests the way they were. Also, at the same time we're trying to think of 100 years out — we want trees in this area.”
What’s happening now, he explained, is a selection event where nature gets to dictate which type of trees grow in a particular location. Instead of sending reinforcements, the service might opt to have land managers plant different tree species in these locations.
“If we're going to assume that climate change is going to continue and maybe these drought events are going to come back, hopefully they go away, but they might come back because droughts happen with or without climate change, then maybe they're going to lean towards ponderosa pines in those locations, or more drought-tolerant types of species,” DePinte said. “And really, nature is doing that on its own.”
DePinte hopes this point, along with the service’s unprecedented observations this year, will help inform landowners when deciding which trees to continue planting in the future.
“Think about which trees are actually going to survive,” DePinte said. “If you wanted a conifer tree, there's a variety of trees you can choose from and maybe just look a little bit deeper into which ones are going to last through climate change and through the foreseeable future.”
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