Ancient redwoods recover from fire by sprouting 1000-year-old buds

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https://www.science.org/content/article/ancient-redwoods-recover-fire-sprouting-1000-year-old-buds

Ancient redwoods recover from fire by sprouting 1000-year-old buds

After a devastating conflagration, trees regrow using energy stored long ago

1 DEC 2023•5:55 PM ET•BY ERIK STOKSTAD

When lightning ignited fires around California’s Big Basin Redwoods State Park north of Santa Cruz in August 2020, the blaze spread quickly. Redwoods naturally resist burning, but this time flames shot through the canopies of 100-meter-tall trees, incinerating the needles. “It was shocking,” says Drew Peltier, a tree ecophysiologist at Northern Arizona University. “It really seemed like most of the trees were going to die.”

Yet many of them lived. In a paper published yesterday in Nature Plants, Peltier and his colleagues help explain why: The charred survivors, despite being defoliated, mobilized long-held energy reserves—sugars that had been made from sunlight decades earlier—and poured them into buds that had been lying dormant under the bark for centuries.

“This is one of those papers that challenges our previous knowledge on tree growth,” says Adrian Rocha, an ecosystem ecologist at the University of Notre Dame. “It is amazing to learn that carbon taken up decades ago can be used to sustain its growth into the future.” The findings suggest redwoods have the tools to cope with catastrophic fires driven by climate change, Rocha says. Still, it’s unclear whether the trees could withstand the regular infernos that might occur under a warmer climate regime.

Mild fires strike coastal redwood forests about every decade. The giant trees resist burning thanks to the bark, up to about 30 centimeters thick at the base, which contains tannic acids that retard flames. Their branches and needles are normally beyond the reach of flames that consume vegetation on the ground. But the fire in 2020 was so intense that even the uppermost branches of many trees burned and their ability to photosynthesize went up in smoke along with their pine needles.

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https://www.nature.com/articles/s41477-023-01581-z
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Article
Published: 30 November 2023

Old reserves and ancient buds fuel regrowth of coast redwood after catastrophic fire

Drew M. P. Peltier, Mariah S. Carbone, Melissa Enright, Margaret C. Marshall, Amy M. Trowbridge, Jim LeMoine, George Koch & Andrew D. Richardson

Abstract

For long-lived organisms, investment in insurance strategies such as reserve energy storage can enable resilience to resource deficits, stress or catastrophic disturbance. Recent fire in California damaged coast redwood (Sequoia sempervirens) groves, consuming all foliage on some of the tallest and oldest trees on Earth. Burned trees recovered through resprouting from roots, trunk and branches, necessarily supported by nonstructural carbon reserves. Nonstructural carbon reserves can be many years old, but direct use of old carbon has rarely been documented and never in such large, old trees. We found some sprouts contained the oldest carbon ever observed to be remobilized for growth. For certain trees, simulations estimate up to half of sprout carbon was acquired in photosynthesis more than 57 years prior, and direct observations in sapwood show trees can access reserves at least as old. Sprouts also emerged from ancient buds—dormant under bark for centuries. For organisms with millennial lifespans, traits enabling survival of infrequent but catastrophic events may represent an important energy sink. Remobilization of decades-old photosynthate after disturbance demonstrates substantial amounts of nonstructural carbon within ancient trees cycles on slow, multidecadal timescales.