• Discovery uncovers a new leaf for Redwoo

    From ScienceDaily@1:317/3 to All on Wednesday, March 16, 2022 22:30:42
    Discovery uncovers a new leaf for Redwoods
    Redwood trees havetypes of leaves, and they do totally different
    things

    Date:
    March 16, 2022
    Source:
    University of California - Davis
    Summary:
    Redwood trees have two types of leaves, one to make food and the
    other to absorb water, found a new study. It's the first study to
    estimate whole- crown water absorption in a large, mature tree. The
    findings can help scientists monitor redwoods' adaptability amid
    a changing climate and deepens our understanding of the resilience
    of these massive trees.



    FULL STORY ========================================================================== Redwoods are among the most well-studied trees on the planet, and yet
    their mysteries continue to surprise and delight scientists and nature
    lovers.


    ========================================================================== Scientists from the University of California, Davis, discovered
    that redwood trees have two types of leaves, and those leaves have
    completely different jobs, according to a study in the American Journal of Botany. Together, these functionally distinct leaves allow the world's
    tallest trees to thrive in both wet and dry parts of their range in
    California, without sacrificing water or food.

    Division of labor The peripheral leaf spends its working hours
    making the tree's food - - converting sunlight into sugar through photosynthesis. Its colleague, the axial leaf, does almost nothing to
    help with photosynthesis. Instead its specialty is to absorb water. In
    fact, the study found that a large redwood can absorb up to 14 gallons
    of water in just the first hour its leaves are wet.

    How does that compare to other trees? Scientists don't know. This is
    the first study estimating whole-crown water absorption in a large,
    mature tree. Because large redwoods have over 100 million leaves, this absorption record may prove hard to beat.

    In wet forests, photosynthesis can be inhibited by films of water covering
    leaf stomata when they get wet. For redwoods, the different leaf types
    allow the trees to get wet and still be able to photosynthesize. The
    peripheral leaves have a waxy coating that slows water absorption but
    may help them continue photosynthesis throughout the wet season.



    ==========================================================================
    "I'd be surprised if there weren't a lot of conifers doing this," said
    lead author Alana Chin, a Ph.D. student in ecology with the UC Davis
    Department of Plant Sciences at the time of the study. "Having leaves
    that aren't for photosynthesis is in itself surprising. If you're a
    tree, you don't want to have a leaf that's not photosynthesizing unless
    there's a very good reason for it." Trading spaces The study also found
    that leaves can shift their "office space" along the tree depending on
    whether the environment is wet or dry.

    In the wet, rainy north coast, the water-absorbing leaf type is found
    on the tree's lower branches, leaving the upper, sunnier levels to the photosynthesizing leaf type. That dynamic flips for redwoods in their
    southern range: The water-collectors live among the tree's higher levels
    to take more advantage of fog and rain, which occur less often in the
    drier environment.

    To arrive at their findings, the authors collected shoot clusters from
    six redwood trees at five forest locations stretching from wet Del Norte
    County to the dry Santa Cruz Mountains and exposed them to experimental
    fog. They estimated the water absorption potential for seven additional
    trees - - including the tallest living tree -- and took samples at
    varying heights.



    ==========================================================================
    They then compared the anatomy and measured photosynthesis of the
    peripheral and axial leaves to understand their function. They also
    developed a physics- based causal model that allowed them to determine
    the leaf traits that regulate absorption rates.

    Amid all the findings, Chin is most excited to have found an easy
    and effective way to indicate redwood trees' ability to access
    fog. Researchers can monitor how and if redwoods are adapting to climate conditions and a future, drier world by simply looking at the visible
    waxes covering the two types of leaves - - something that could be
    captured on a cell phone camera and shared by other scientists or even
    members of the public.

    Superlative species Redwoods are renowned for their resilience in the
    face of many natural threats and inspire numerous superlatives: They are
    among the planet's biggest, tallest, oldest trees. They have tannin-rich heartwood, fire-resistant bark and pest-resistant leaves. This new
    finding is another example of their ability to respond to environmental conditions, like drought and water stress.

    "The cool thing here is their ability to thrive under all these
    circumstances and adjust themselves to these different environments,"
    said Chin, who grew up near the redwoods in Mendocino County. "That
    things like this can be happening right under our nose in one of the best-studied species out there -- none of us assumed this would be the
    story." Study co-authors include Paula Guzman-Delgado, Jessica Orozco,
    Zane Moore and senior author Maciej Zwieniecki of the UC Davis Department
    of Plant Sciences, as well as Stephen Sillett, Lucy Kerhoulas and Marty
    Reed of Cal Poly Humboldt, and Russell Kramer of Dipper and Spruce LLC
    in Washington.

    The study was funded by the National Science Foundation and a Katherine
    Esau Fellowship from UC Davis.


    ========================================================================== Story Source: Materials provided by
    University_of_California_-_Davis. Original written by Kat Kerlin. Note:
    Content may be edited for style and length.


    ========================================================================== Related Multimedia:
    * Two_different_leaves_of_redwood_trees ========================================================================== Journal Reference:
    1. Alana RO Chin, Paula Guzma'n‐Delgado, Stephen C Sillett,
    Jessica
    Orozco, Russell D Kramer, Lucy P Kerhoulas, Zane J Moore, Marty
    Reed, Maciej A Zwieniecki. Shoot dimorphism enables Sequoia
    sempervirens to separate requirements for foliar water uptake
    and photosynthesis.

    American Journal of Botany, 2022; DOI: 10.1002/ajb2.1841 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220316132706.htm

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