Posted on 12/04/2023 7:57:00 AM PST by Red Badger
After a devastating conflagration, trees regrow using energy stored long ago
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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.
Trees photosynthesize to create sugars and other carbohydrates, which provide the energy they need to grow and repair tissue. Trees do store some of this energy, which they can call on during a drought or after a fire. Still, scientists weren’t sure these reserves would prove enough for the burned trees of Big Basin.
Visiting the forest a few months after the fire, Peltier and his colleagues found fresh growth emerging from blackened trunks. They knew that shorter lived trees can store sugars for several years. Because redwoods can live for more than 2000 years, the researchers wondered whether the trees were drawing on much older energy reserves to grow the sprouts.
For the study, Melissa Enright of the U.S. Forest Service covered parts of 60 charred tree trunks in black plastic to block out sunlight, ensuring any new sprouts grew only with stored energy, not new sugar from photosynthesis. After 6 months, the team brought the sprouts back to the lab. There, they radiocarbon dated the molecules within to calculate the average age of those sugars. At 21 years, they are the oldest energy reserves shown to be used by trees. (A previous study had clocked 17 years in maples.)
Average age is only part of the story. The mix of carbohydrates also contained some carbon that was much older. The way trees store their sugar is like refueling a car, Peltier says. Most of the gasoline was added recently, but the tank never runs completely dry and so a few molecules from the very first fill-up remain. Based on the age and mass of the trees and their normal rate of photosynthesis, Peltier calculated that the redwoods were calling on carbohydrates photosynthesized nearly 6 decades ago—several hundred kilograms’ worth—to help the sprouts grow. “They allow these trees to be really fire-resilient because they have this big pool of old reserves to draw on,” Peltier says.
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.”
doi: 10.1126/science.zh27a7r
THIS BUD'S FOR YOU!..........................
Redwoods - water won’t rot it, fire won’t destroy it, bugs don’t like, and its light to carry. They get big and old. Closest thing in nature I have been in that is like a cathedral.
One thing I do not get, how can buds that just sprouted be 1000 years old, the tree sure, but the buds?
The buds aren’t 1,000yrs old; the tree might be. Many trees do this. I’m a Horticulturalist/Botanist and this is not unusual in Nature.
Quick! Cut em all Down! Can’t risk forret fires! Depopulate the forests of their trees!
That’s what I thought, the title of the article is not correct.
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.The author asks "Another question is how the redwoods would cope if a second catastrophic fire strikes soon."
But earlier the article points out the inferno devastated the canopy of the trees, so there's nothing left to burn. How would a second catastrophic fire occur without fuel?
Another question is how the redwoods would cope if Bill Gates decided to buy and bury them like he plans to do with 70,000 other trees?
Someone over at that pub can’t write coherently; you’re right,
I have a couple ‘old growth’ redwoods about 10 feet in diameter. They’re hollowed out by fire from wood rats building nests at the base. When a ground fire comes through the nest burns like a blow torch, burns through the bark and kills the whitewood in that area. Repeat and you’ll end up with a tree gutted 30 feet up with an annular growth ring a foot thick and 3/4 of the circumference. I use tag ends of redwood lumber as kindling in my stove. Burns great and green branches burn just fine.
This is all by design. Just as some species like Douglas Fir are not SHADE tolerant. Which is why for the seedlings to grow you have to CLEAR CUT. Meaning the small young seedlings will NOT grow if they are in the shade of larger trees. Some species will ONLY repopulate AFTER a forest fire. Natures way.
Right, the limbs can and do burn and the trees bark can be burnt but the tree themselves do not as noted by this article.
“How would a second catastrophic fire occur without fuel?”
It will not.
The trees have adapted to this. See my post.
At least that is what I recall from the text book of Dendrology at the SUNY College of Environmental Science and Technology. Where they literally wrote the book.
“It is amazing to learn that carbon taken up decades ago can be used to sustain its growth into the future.”
Hooray for carbon!
You wrote “some species like Douglas Fir are not SHADE tolerant. Which is why for the seedlings to grow you have to CLEAR CUT. Meaning the small young seedlings will NOT grow if they are in the shade of larger “
Hence the well-known species succession after fires if you don’t clear cut.
Sorry, I am getting old. Should be:
the SUNY College of Environmental Science and Forestry @ Syracuse University.
I can’t even remember where I went to college.
With a memory like that, you must be as old as those redwood trees!
call The Lorax
The next fire might be a hundred years later...
1985 Alumni
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