The Science of Sustainability

Redwood Regeneration

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This redwood, in Henry Cowell Redwoods State Park near Santa Cruz, might be genetically identical to some of its neighbors. Photo: kqedquest.

QUEST has an inordinate fondness for albino redwoods. It all started with the Science on the SPOT video Albino Redwoods, Ghosts of the Forest. Then there was a radio story, and a few blog posts. And last week QUEST revisited the research in two new Science on the SPOT videos about the ghosts of the forest. The video Revisiting Albino Redwoods, Cracking the Code focuses on QUEST blogger Barry Star and Stanford professor Ghia Euskirchen’s research on how the albinos are genetically different from “normal” coast redwoods. In Revisiting Albino Redwoods, Biological Mystery, Santa Cruz Professor Jarmila Pitterman wonders how albino redwoods’ total lack of chlorophyll affects their physiology and ecology. After producing all these videos, QUEST Producer Chris Bauer still had questions.

Chris saw three albino redwoods, arranged in a straight line, a short distance from one another. He wondered if these three redwoods, yards apart, might be genetically identical. Maybe they sprung from the same individual. To understand how this is even possible, you need to know about the numerous ways that redwoods can reproduce—some of which involve cloning themselves.

New redwood trees can come about in four ways: through seeds, cuttings, stump sprouts, and root sprouts.


QUEST on KQED Public Media.

Like all plants, redwoods can grow from seeds. Redwood seeds come from those tiny, inch-long redwood cones that fall from the branches in autumn. Each cone contains one to two dozen tiny seeds. These seeds were fertilized with redwood pollen; they are mix of genetic material from the parent that made the seed and the parent that made the pollen. However, redwood seeds have a notoriously low germination rate. Hardly any of them will grow into a plant. Which brings us to the next method of redwood tree generation: cuttings.

Redwood trees that you buy from a nursery probably began as cuttings—branches that were cut from a tree. To make a good redwood cutting, horticulturists will cut a branch from a young tree, or sapling, because cuttings from young trees tend to survive better. They treat the cutting with hormones to encourage growth, and plant the cutting in a special blend of soils. After a few months, about 25-35% of the cuttings have formed roots; the others do not survive. Once the cuttings have established, they can grow quite quickly—up to 7 feet in height in a single growing season. Regeneration from existing branches doesn’t just happen in the nursery—it happens in nature too. When a branch falls off a redwood tree, say in a storm, the branch can come in contact with the soil and develop roots. These provide the branch with nutrients and water, and before long the branch has grown into a tree. Trees grown from cuttings or from branches are genetically identical of the tree that donated the branch. (For the same reason, California’s vineyards are very low in genetic diversity; see this article in the New York Times.)

Stump sprouts on a coast redwood. Photo: kqedquest.

Many a majestic redwood tree began as a stump sprout. Stump sprouts are tiny growths from the base of existing trees. They can grow out of a healthy tree, or a tree that has been logged or damaged by fire. Redwoods have extensive underground root systems, which are impervious to trifling things like lumberjacks’ axes and fire. Trees that grow from stumps grow quickly and have a good chance of success, because the trees are automatically connected to a large root system. Multiple stump sprouts from a single trunk form what is called a fairy ring: a ring of trees, with a circular clearing in the middle, because the original tree breaks down. Stump sprouts are generally genetic clones of the original tree. However, the albino redwoods are stump sprouts with a mutation (or two, or three…). The genomic research happening Stanford will hopefully shed some light on how this mutation happens.

A fairy ring. The ring of trees has sprouted from the moss-covered trunk in the middle. Photo: Swiv.

Redwoods don’t just sprout from stumps; they can also sprout new growth from their roots. Redwood roots extend horizontally under the soil. Many redwoods live in flood-prone ecosystems, on the banks of rivers. When redwood forests become flooded, sediment piles up on the surface of the soil, burying the roots a bit deeper than they were before. Redwoods will grow another set of horizontal roots, a little closer to the surface. By digging deep into the ground and counting the horizontal layers of roots, people can tell how many floods a redwood has endured. When new growth sprouts from the surface roots, the original tree soon has a neighbor that is basically an identical twin. This is what Chris thinks is going on with the three albino redwoods, all in a row.

Hopefully Chris can test his hypothesis in a year or two, when the redwood genome is sequenced and we know what mutation (or mutations) cause albinism. Are the three neighboring albino redwoods mutants that sprung from genetically identical trees? Maybe that tree’s genotype is just a little different from that of an albino—and the mutation that causes albinism is very likely to occur. Or maybe the three albinos are a series of chlorophyll-free coincidences. We’ll have to wait patiently for the genome data. But, for a coast redwood that can live for 2,000 years, the wait won’t be long at all.

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Category: Biodiversity, Biology

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Jennifer Skene

About the Author ()

Jennifer Skene develops curriculum on climate change and ocean sciences at the Lawrence Hall of Science and teaches biology and science communication at Mills College and the University of California Berkeley. She has a degree in biology from Brown University and a Ph.D. in Integrative Biology from UC Berkeley. She started working with QUEST in 2008 as an intern. She has written for the Berkeley Science Review and the UC Museum of Paleontology’s Understanding Evolution and Understanding Science websites.
  • Mario Vaden

    This reminds me of last year when I was measuring LiDAR redwoods with Atkins in Prairie Creek, and saw about 5 or more Curly Redwoods all in a straight row. I'm pretty sure they are all from one moderately tall but narrow-trunked tree that fell years ago, and sprouted along the trunk.

    Your 3 Albino Redwoods in a row could also be from one albino redwood that had something fall on it, pressing it down into the earth some, then sprouts emerging along its trunk.

    Sort of like the horizontal trunk that spans a creek on Hiouchi trail at Jedediah Smith, just smaller, and embeded in the earth some.

    Sound possible? If it has not been proved impossible, could that be possible? That option may need to be ruled-out before coming to other conclusions.

    Cheers,

    M. D. Vaden of Oregon

  • Jennifer Skene

    Great hypothesis, Mario! I wonder if an albino redwood could grow tall enough to span the distance between the albino plants that Chris saw? I think albino redwoods tend to be pretty small, because they can't photosynthesize—they rely on other plants to supply their energy. In the QUEST videos, the albino redwoods look more like shrubs. Does anyone know how big albino redwoods can grow?

    Jen

  • Mario Vaden

    Last year I used a laser to measure one albino redwood near Rockefeller forest. It was about 40 feet tall. Would one like that be close to tall enough? How far apart were the 3 albino redwoods that Chris saw in a line? Cheers / M. D. Vaden

  • Chris Bauer

    Great article Jennifer! And thanks for your insights and questions Mario. Some of this was brought up a bit in the discussion after our first albino redwoods story. See: http://www.kqed.org/quest/blog/2010/08/26/producers-notes-for-science-on-the-spot-albino-redwoods-ghosts-of-the-forest/

    There are now eight known “albino redwoods” found in or around Henry Cowell Redwoods State Park. The three that we’re talking about here are found one-two-three in close proximity to each other. I’d say each is 15 to 25 yards apart in a line, maybe 100 to 150 feet from one end to the other. Our docent guide Dave Kuty surmised they are probably related in some way. We’re just guessing but I would agree.

    Knowing the albino redwoods are sprouts off a “mother tree,” getting all the nutrients to survive from that “host tree,” and given what we now know about redwood regeneration, we kicked around the idea that their different “mother trees” are somehow related or may be clones from the same parent- The “grand parent” of the albinos, so to speak. So here’s the thinking- Long long ago, before anyone was around to hear, a big mother redwood fell in the prehistoric forest. Somewhere in that seemingly “normal” tree there was perhaps a recessive gene that allowed for what we are calling albinism. New trees sprouted off that fallen tree, which decomposed and was eventually replaced by the now huge cloned offspring. Those trees also carry the gene for albinism and thus today have produced these white sprouts. This is all wild conjecture at this point. I have nothing to back up my theory. But hopefully the work by Ghia Euskirchen and the other geneticists at Stanford will shed some light on this.

    Another somewhat related question I have is connected to one of those lined up albinos. The top one in the line is found along the train tracks of the Roaring Camp Railroad. Another albino redwood, the most recently discovered one at Henry Cowell Redwoods State Park, is also found along the tracks, alone a few miles away. Now I wonder if these two are also related. Could the old train have somehow inadvertently transported pollen or seed or something else and spread the redwood DNA along the rail line? I know that’s reaching. But maybe it’s something else we’ll learn when the DNA sequencing comes in.

    Thanks again for this discussion. It’s always fun to wildly speculate and hypothesize before the real scientific data comes in to remind me that I don’t know as much as I think I do!

    Cheers!
    -Chris

  • Mario Vaden

    Ah – hah – up to 150 feet from end to end. Thanks for sharing that and the other details.

    Likewise, the fallen parent or mother tree could also have been a tall skinny one too – very young. Big redwoods and other big conifers knock down small ones from time to time. Now it was not a redwood, but in January, when we found the world's new tallest pine at 268 feet, we were gawking at a 220 foot tall Ponderosa that was maybe 2 feet diameter. Seen similar in the redwoods.

    The albino redwoods have been of interest to me, not just becauee they are are rare, but because I'm curious about what they can do and what they can't do. Can they be propagated? How hard or easy are they to propagate? Can an albino redwood layer roots into the ground if it falls provided its still connected to another redwood with chlorophyll? Can they get taller than what we see, and are the short one due to a combination of slower growth rate coupled with past forest fires torching the stems?

  • team whipper

    it would be interesting to know the rate of mutation in the apical tips of redwoods. for a species that relies less on sexual reproduction, and more heavily on cloning, higher rates of apical tip mutation could be a favorable way to increase the genetic diversity that leads to better adaptation.
    this is an interesting story, and interesting following comments. thanks for bringing it to us, Ms Skene.

  • J. Hollister

    Is there a hormone like gibberryllic acid or an auxin (dilute 2,4 D?) that I could apply to my Soquel Coastal Redwood by drilling small holes in the trunk to encourage more lower limbs to grow?

    (My city's Urban Forestry Department cut the lower limbs 360 degrees around my redwood. I planted it 20 years ago and the limbs were two to three inches thick. The city had a right to cut limbs above the sidewalk, but not five feet higher than the required eight feet above the sidewalk (about 13 feet total). They had no right to cut on my yard side of the tree at all. The limbs screened out all the houses I could see over my fence. The city is not going to replace the tree.) I am looking for a way to quickly encourage lower limb growth.

  • J. Hollister

    Sorry for the repeat; I had to reenter the correct email address.

    Is there a hormone like gibberryllic acid or an auxin (dilute 2,4 D?) that I could apply to my Soquel Coastal Redwood by drilling small holes in the trunk to encourage more lower limbs to grow?
    (My city's Urban Forestry Department cut the lower limbs 360 degrees around my redwood. I planted it 20 years ago and the limbs were two to three inches thick. The city had a right to cut limbs above the sidewalk, but not five feet higher than the required eight feet above the sidewalk (about 13 feet total). They had no right to cut on my yard side of the tree at all. The limbs screened out all the houses I could see over my fence. The city is not going to replace the tree.) I am looking for a way to quickly encourage lower limb growth.