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Nature plans ahead: how redwoods survive fire…

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 [in late November] 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.

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It’s not just the energy reserves that are old. The sprouts were emerging from buds that began forming centuries ago. Redwoods and other tree species create budlike tissue that remains under the bark. Scientists can trace the paths of these buds, like a worm burrowing outward. In samples taken from a large redwood that had fallen after the fire, Peltier and colleagues found that many of the buds, some of which had sprouted, extended back as much as 1000 years. “That was really surprising for me,” Peltier says. “As far as I know, these are the oldest ones that have been documented.”

Although the redwoods have sprouted new growth, Peltier and other forest experts wonder how the trees will cope with far less energy from photosynthesis, given that it will be years before they grow as many needles as they had before the fire. “They’re alive, but I would be a little concerned for them in the future.”

Another question is how the redwoods would cope if a second catastrophic fire strikes soon. Have they used up their emergency reserves? “The fact that the reserves used are so old indicates that they took a long time to build up,” says Susan Trumbore, a radiocarbon expert at the Max Planck Institute for Biogeochemistry. “Redwoods are majestic organisms. One cannot help rooting for those resprouts to keep them alive in decades to come.”…

After a devastating conflagration, trees regrow using energy stored long ago: “Ancient redwoods recover from fire by sprouting 1000-year-old buds,” from @ScienceMagazine.

* John Muir

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As we learn from nature, we might spare a thought for Louis Agassiz; he died on this date in 1873. A biologist and geologist, he was an important early scholar of Earth’s natural history. After studying with Georges Cuvier and Alexander von Humboldt in Paris, Agassiz was appointed professor of natural history at the University of Neuchâtel. He emigrated to the United States in 1847 after visiting Harvard University and went on to become professor of zoology and geology at Harvard, to head its Lawrence Scientific School, and to found its Museum of Comparative Zoology.

Agassiz is known for observational data gathering and analysis. He made institutional and scientific contributions to zoology, geology, and related areas, including multivolume research books running to thousands of pages. He founded the field of glaciology.

His second wife, Elizabeth Cabot Agassiz (née Cary) collaborated with him on much of his work and went on to found Radcliffe College.

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