Northern California’s giant sequoia trees, some more than 3,000 years old, were under threat by an encroaching wildfire on Friday.  

The Washburn Fire forced the closure of a section of Yosemite National Park Friday morning and was estimated to have burned 250 acres by noon as it approached the lower portion of Mariposa Grove, park officials from Yosemite said.

Giant sequoias are the largest trees in the world, by volume and have existed alongside lightning ignited fires that improved forest health in the Sierra Nevada region for thousands of years, biologists say.  

The last century of federal fire suppression and poor forest management has left dead trees and brush which have become fuel for massive wildfires.

The U.S. is in the midst of its worst wildfire year in more than a decade, more than 4.7 million acres have burned this year.

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