SHERWOOD, ORE. • Deep inside a forest in Oregon’s Willamette Valley stands a dead “Tree of Life.”

Its foliage, normally soft and green, is tough and brown or missing altogether. Nonetheless, the tree’s reddish bark, swooping branches and thick, conical base identify it as the Pacific Northwest’s 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’s trunk. Twisting the handle of the corkscrew-like borer, Buhl extracts a long, thin sample of the tree’s inner growth rings.

The rings become thinner over time, indicating the tree’s growth slowed before the tree finally died, a sign that this red cedar, like thousands of others in Oregon and Washington, died from drought.

For thousands of years, people have used red cedar to make everything from canoes to clothing. Its many uses have earned the species endearing names, including the “Tree of Life.” Last year, Buhl and colleagues reported that red cedars were dying throughout the tree’s growing range not because of a fungus or insect attack, but due to the region’s “climate change-induced drought.”

Red cedars aren’t alone. In recent years, at least 15 native Pacific Northwest tree species have experienced growth declines and die-offs, 10 of which have been linked to drought and warming temperatures.

Many researchers, Buhl included, are 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.

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 “Firmageddon.” referring to the more than 1,875 square-mile die-off of five fir species in Oregon, Washington and northern California.

“The forests are moving uphill,” said DePinte.