USGS Western Ecological Research Center

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Scientists at the USGS Western Ecological Research Center study the many ecosystems of the Pacific Southwest. Follow our expeditions and projects through this outreach page, and learn more about your local landscape with our library of Outreach Factsheets and photos. Thanks for joining us!

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Giant sequoia, Mariposa Grove, Yosemite National Park --Photographer: Ben Young Landis/USGS
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When a Giant Sequoia Falls Down...
Giant sequoia (Sequoiadendron giganteum) can live for thousands of years and grow to over 200 feet in height. So when a large sequoia comes crashing down -- in plain view of visiting tourists, no less -- it causes quite a stir.

A few weeks ago, a German tourist hiking the Trail of 100 Giants in Sequoia National Forest witnessed the fall of a pair of giant sequoia, estimated at some 1,500 years old. Now the USDA Forest Service must decide how to incorporate these now-resting behemoths into its trail system and the natural landscape.

Though the crash itself is dramatic, it was simply a natural end to the long-life of an organism. As USGS research ecologist Nate Stephenson told the Los Angeles Times:

"Sequoias do fall. That's how big sequoias die... It's never anything that I consider with alarm."

Stephenson is a lead scientist at the Sequoia and Kings Canyon Field Station at the USGS Western Ecological Research Center. Stephenson and his WERC colleagues have been analyzing tree deaths in the western United States, as part of their research focus on forest ecology.

What is alarming is a 2009 study led by Stephenson and WERC colleague Phil van Mantgem, where they found that tree deaths have doubled across the western U.S. in recent decades.

Regional warming of temperatures -- with consequences such as reduced snowpack and lengthened summer droughts -- may be stressing many western tree species. And just as with humans, when trees get stressed, they become more prone to diseases.

Stephenson, van Mantgem and their research partners through the Western Mountain Initiative are continuing to examine how mountain ecosystems -- such as the sequoia and redwood groves of California -- are faring under changing global conditions.

-- Ben Young Landis

Visitors touching a fallen sequoia at Mariposa Grove, Yosemite National Park --Photographer: Ben Young Landis/USGS
Fallen giant sequoias sometimes serve as valuable teaching tools. This sequoia stump in Yosemite National Park has been polished to showcase its ancient tree rings. Image credit: Ben Young Landis/USGS.

Top Image: A giant sequoia in Yosemite National Park. Image credit: Ben Young Landis/USGS

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