Deep inside a forest in Oregon害羞草研究所檚 Willamette Valley stands a dead 害羞草研究所淭ree of Life.害羞草研究所�
Its foliage, normally soft and green, is tough and brown or missing altogether. Nonetheless, the tree害羞草研究所檚 reddish bark, swooping branches and thick, conical base identify it as the Pacific Northwest害羞草研究所檚 iconic western red cedar.
Christine Buhl, a forest health specialist for the Oregon Department of Forestry, plunges a tool called an increment borer into the dead tree害羞草研究所檚 trunk. Twisting the handle of the corkscrew-like borer, Buhl extracts a long, thin sample of the tree害羞草研究所檚 inner growth rings.
The rings become thinner over time, indicating the tree害羞草研究所檚 growth slowed before the tree finally died, a sign that this red cedar, like thousands of others in Oregon and Washington, died from drought.
害羞草研究所淭hat害羞草研究所檚 why it害羞草研究所檚 the canary,害羞草研究所� says Buhl. 害羞草研究所淎ny tree that害羞草研究所檚 less drought tolerant is going to be the canary in the coal mine. They害羞草研究所檙e going to start bailing (out).害羞草研究所�
For thousands of years, people have used red cedar to make everything from canoes to clothing.
Red cedar害羞草研究所檚 many uses have earned the species endearing names, including the 害羞草研究所淭ree of Life.害羞草研究所� More recently, scientists have started calling this water-loving relative of redwoods by a less flattering name: 害羞草研究所渢he climate canary.害羞草研究所�
Last year, Buhl and colleagues throughout the tree害羞草研究所檚 growing range not because of a fungus or insect attack, but due to the region害羞草研究所檚 害羞草研究所渃limate change-induced drought.害羞草研究所�
Red cedars aren害羞草研究所檛 alone.
In recent years, at least have experienced growth declines and die-offs, 10 of which have been linked to drought and warming temperatures, according to .
Many researchers, Buhl included, are now arguing that these drought-driven die-offs are the beginning of a much larger and long-predicted shift in tree growing ranges due to climate change.
Trees, and plants generally, have growing ranges that are largely determined by climate factors, namely moisture and temperature.
For decades, scientists have argued that as atmospheric warming continues, growing ranges in the Northern Hemisphere will shift upslope in elevation and farther north, leaving many trees stranded in a warmer, drier world.
As climate mismatch sets in, trees are expected to die-off and not grow back, according to predictions.
Daniel DePinte, Forest Service aerial survey program manager, suspects range changes are driving 害羞草研究所淔irmageddon.害羞草研究所� A term coined by researchers, including DePinte, 害羞草研究所淔irmageddon害羞草研究所� refers to the more than 1,875 square-mile (4,856-square-kilometer) die-off of five fir species in Oregon, Washington and northern California.
害羞草研究所淭he forests are moving uphill,害羞草研究所� said DePinte.
DePinte and colleagues first identified and named the massive, drought-driven fir 害羞草研究所渕ortality event害羞草研究所� last year while surveying area forests via airplane.
According to tree-range predictions, climate-induced die-offs are expected to start at the edges of growing ranges, including at lower-elevation locations that are predicted to become too warm and dry for many species.
DePinte害羞草研究所檚 survey revealed that the largest die-offs associated with Firmageddon are occurring at lower-elevation sites.
Buhl and colleagues found a similar pattern with western red cedar. Mortality was greatest at sites less than about 650 feet (200 meters) in elevation west of the Cascade Range, according to their analysis.
Scientists have also observed a similar pattern for Douglas fir, the region害羞草研究所檚 leading commercial timber species. Douglas fir is currently experiencing a 720-square-mile (1,865-square-kilometer) die-off, the majority in the Klamath Mountains near the southern Oregon cities of Ashland and Medford.
The die-off is limited to the lower elevations but is likely to move uphill as temperatures warm in the coming decades, according to a study in the .
害羞草研究所淥ur analysis concluded that if climate change continues as predicted, we could see increased Douglas fir mortality at higher elevations,害羞草研究所� said study coauthor, David Shaw, a professor and forest health specialist at Oregon State University.
Shaw called the die-off 害羞草研究所渃onsistent with predictions for climate change.害羞草研究所�
But whereas red cedar is believed to be dying from drought alone, the Firmageddon and Douglas fir die-offs have been linked to a combination of drought weakening trees and insect pests moving in for the kill.
害羞草研究所淭hese insects are not normally tree killers,害羞草研究所� said DePinte. 害羞草研究所淭his is evidence that the forests are reacting to climate change and droughts.害羞草研究所�
Douglas fir is not considered a true fir and is not officially part of Firmageddon, according to DePinte.
The combination of drought-induced stress and pests, said Patrick Tobin, associate professor of disturbance ecology at the University of Washington, is analogous to a person with a weakened immune system dying from the flu.
害羞草研究所淒rought-stress opens a window for biotic agents that might otherwise not be able to overcome a healthy, well-defended tree,害羞草研究所� said Tobin.
Tobin is a coauthor of a 2021 study in the journal Forest Ecology and Management on the widespread decline of big leaf maples in western Washington. Tobin害羞草研究所檚 study was unable to determine whether drought alone or drought in combination with disease-causing fungi was killing the native maples.
As for the climate canary, Buhl believes red cedar is unlikely to disappear from the landscape entirely but probably won害羞草研究所檛 grow back in areas where it害羞草研究所檚 dying off.
害羞草研究所淯nless we turn back climate change, there is no reason to hope western red cedar is going to make a comeback,害羞草研究所� said Buhl.
EDITOR害羞草研究所橲 NOTE: This story is part of a collaboration between The Associated Press and Columbia Insight, exploring the impact of climate on trees in the Pacific Northwest.
