CSI Colorado: Sudden Aspen Decline Post-Mortem

Droughts kill trees — but until now scientists didn’t know the root of the problem

Aspens live at high elevations in the Western United States, including in California’s White Mountains and Sierra Nevada.

Throughout the West, aspens are quaking for good reason.

About 17% of the aspen in the Colorado Rockies have died in the last decade. That’s about one in every six trees. The widespread die-off, called sudden aspen decline, began after a severe drought and heat wave. So people studying the trees knew that’s what triggered the deaths, but they didn’t know what exactly killed the trees.

William Anderegg, a grad student at Stanford, with help from a team of scientists there and at the University of Utah, has zeroed in on the culprit, and describes the work in a paper published this week. There were two working theories: failures in photosynthesis, which would mean less food for the tree; or damage to the roots, which would mean less water. Anderegg found it was the roots.

“Our study provides a snapshot of what future droughts could hold for the emblematic tree of the American West,” Anderegg said in a press release. “Our results indicate an impaired ability to transport water due to drought damage plays an important role in the recent die-off of aspens,” .

With this research, scientists will be able to better understand and predict how forests will respond to rising temperatures and drier conditions.

CSI Colorado: Sudden Aspen Decline Post-Mortem 1 February,2018Molly Samuel


Molly Samuel

Molly Samuel joined KQED as an intern in 2007, and since then has worked here as a reporter, producer, director and blogger. Before becoming KQED Science’s Multimedia Producer, she was a producer for Climate Watch. Molly has also reported for NPR, KALW and High Country News, and has produced audio stories for The Encyclopedia of Life and the Oakland Museum of California. She was a fellow with the Middlebury Fellowships in Environmental Journalism and a journalist-in-residence at the National Evolutionary Synthesis Center. Molly has a degree in Ancient Greek from Oberlin College and is a co-founder of the record label True Panther Sounds.

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