Count those birthday candles! The tallest redwood tree in California's historic Muir Woods may be only 777 years old — just half the 1,500 years of previous scientific estimates. That's the verdict of researchers who undertook the first dating of trees in the Muir Woods National Monument 12 miles north of San Francisco.
They focused on Tree 76: a 249-foot-tall coast redwood (Sequoia sempervirens.) Although it's the tallest tree in the Muir Woods, its newly determined age means Tree 76 is a youngster compared with giant old-growth trees farther north in the state and elsewhere.
Using tree-ring examination, researchers have determined a coast redwood near Crescent City, Calif., is 2,250 years old, and an example of the giant sequoia species that grows in the Sierra Nevada has been dated as 3,240 years old.
For the Muir Woods survey, researchers from Humboldt State University utilized a technique in which pencil-thin core samples are extracted from the trees at different heights and compared with other trees. This process yielded the estimate for Tree 76 of 777 years. That's plus or minus 34 years, the researchers are quick to point out.
The Humboldt study was undertaken as part of a project to document the size, age and ring history of trees in old-growth redwood groves throughout the state, sponsored by San Francisco's Save the Redwoods League.
In terms of the health of the trees, the results of the Muir Woods survey are encouraging, according to league science director Emily Burns. The trees are growing faster as they age, in spite of climate change and several years of sustained drought.
That's because redwoods "tend to grow in some of the wettest places in California," she explained, so even when most of the state is in the grip of a drought and sees little rain, the tallest forests are in regions covered in fog, rooted in generally wet soil or are located at the foot of mountain snow runoff channels.
The researchers added that the reason the Muir Woods grove is so much younger than most redwood groves in surrounding regions is currently unknown . Burns suggested that natural disasters, such as wildfires or landslides, may have wiped out older generations of trees in the grove, forcing the forest to undergo regeneration.
The location of Muir Woods is in the southern reaches of the redwood forests that stretch along a coastal strip from Big Sur, south of San Francisco, up to southwest Oregon.
