California's giant sequoias showing drought stress

California’s four-year drought is taking its toll on giant sequoia trees, with visible effects starting to show up. It’s the first time in history that the trees have shown drought exhaustion, according to NPR.

The threat to the trees, some of which are more than 3,000 years old, has brought together the National Park Service, the U.S. Forest Service, Stanford and other agencies to study how the trees respond to severe drought.

Researchers are analyzing more than 40 trees to see how the stress is affecting the historical giants.

To find out more, read the story on NPR’s website.