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Even the mightiest sequoia starts from a tiny seedling.

It is at this life stage that giant sequoias (Sequoiadendron giganteum) are the most vulnerable. Forest ecologists, like Nate Stephenson of the USGS Western Ecological Research Center, fear that steady increases in global temperatures will quicken snowmelts and lengthen summer droughts in future decades -- threatening the survival of sequoia seedlings.

Stephenson explained these threats in an interview with The California Report that aired earlier this December:

"The seeds... are about the size of an oatmeal flake," Stephenson tells reporter Molly Samuel.

According to Stephenson, the fossil record tells us that sequoias were much more widespread at certain points in prehistory -- inland to Nevada and Idaho. But as the global climate became warmer after the last ice age, the range of giant sequoias shrank drastically.

Green and dry giant sequoia cones
A green and closed giant sequoia cone (left) and a dry and open giant seqoia cone (right). Source:…. (Public domain.)

"So what we have is a potential analogue for the future," Stephenson told The California Report. "We [had] a period of time that was warmer and a little bit drier than today -- and sequoias were hovering potentially on the brink of extinction then."

As the global climate swings towards warmer temperatures again, sequoias may experience losses once more. As less seedlings survive, there will be fewer young trees replacing aging and fallen trees.

Research-management partnerships -- like Nate Stephenson's collaborations with Sequoia and Kings Canyon National Parks -- will come in handy as scientists and resource managers continue to tackle the issue of climate impacts on park lands and species.

-- Ben Young Landis

Top Image: Visitors walk around the "Fallen Monarch" -- a long-dead giant sequoia at Yosemite National Park. Image credit: Ben Young Landis/USGS

Middle Image: Giant sequoia cones: on the left is a green and closed cone, while on the right is a dried and open cone with seeds dispersed. Image courtesy of the National Park Service.

fallen giant sequoia
Students walk past the "Fallen Monarch" giant sequoia at Yosemite National Park, CA. (Credit: Ben Young Landis, USGS. Public domain.)


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