Mycorrhizal Networks

Today’s BPotD is the second in the series of BPotD’s contribution to the 2010 UBC Celebrate Research Week.

Lindsay organized today’s entry, selected the links, and introduces Dr. Suzanne Simard:

Dr. Suzanne Simard is a professor with the UBC Faculty of Forestry, where she lectures on and researches the role of mycorrhizae and mycorrhizal networks in tree species migrations with climate change disturbance. Networks of mycorrhizal fungal mycelium have recently been discovered by Professor Suzanne Simard and her graduate students to connect the roots of trees and facilitate the sharing of resources in Douglas-fir forests of interior British Columbia, thereby bolstering their resilience against disturbance or stress and facilitating the establishment of new regeneration.

Dr. Simard writes:

Mycorrhizal fungi form obligate symbioses with trees, where the tree supplies the fungus with carbohydrate energy in return for water and nutrients the fungal mycelia gather from the soil; mycorrhizal networks form when mycelia connect the roots of two or more plants of the same or different species. Graduate student Kevin Beiler has uncovered the extent and architecture of this network through the use of new molecular tools that can distinguish the DNA of one fungal individual from another, or of one tree’s roots from another. He has found that all trees in dry interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests are interconnected, with the largest, oldest trees serving as hubs, much like the hub of a spoked wheel, where younger trees establish within the mycorrhizal network of the old trees. Through careful experimentation, recent graduate Francois Teste determined that survival of these establishing trees was greatly enhanced when they were linked into the network of the old trees.Through the use of stable isotope tracers, he and Amanda Schoonmaker, a recent undergraduate student in Forestry, found that increased survival was associated with belowground transfer of carbon, nitrogen and water from the old trees. This research provides strong evidence that maintaining forest resilience is dependent on conserving mycorrhizal links, and that removal of hub trees could unravel the network and compromise regenerative capacity of the forests.

In wetter, mixed-species interior Douglas-fir forests, graduate student Brendan Twieg also used molecular tools to discover that Douglas-fir and paper birch (Betula papyrifera) trees can be linked together by species-rich mycorrhizal networks. We found that the mycorrhizal network serves as a belowground pathway for transfer of carbon from the nutrient-rich deciduous trees to nearby regenerating Douglas-fir seedlings. Moreover, we found that carbon transfer was enhanced when Douglas-fir seedlings were shaded in mid-summer, providing a subsidy that may be important in Douglas-fir survival and growth, thus helping maintain a mixed forest community during early succession. This is not a one-way subsidy, however; graduate Leanne Philip discovered that Douglas-fir supported their birch neighbours in the spring and fall by sending back some of this carbon when the birch was leafless. This back-and-forth flux of resources according to need may be one process that maintains forest diversity and stability.

Mycorrhizal networks may be critical in helping forest ecosystems deal with climate change. Maintaining the biological webs that stabilize forests may help conserve genetic resources for future tree migrations, ensure that forest carbon stocks remain intact on the landscape, and conserve species diversity. UBC graduate student Marcus Bingham is finding that maintaining mycorrhizal webs may be more important for the regeneration and stability of the dry than wet interior Douglas-fir forests, where resources are more limited and climate change is expected to have greater impacts. Helping the landscape adapt to climate change will require more than keeping existing forests intact, however. Many scientists are concerned that species will need to migrate at a profoundly more rapid rate than they have in the past, and that humans can facilitate this migration by planting tree species adapted to warm climates in new areas. UBC graduate student Brendan Twieg is starting new research to help us understand whether the presence of appropriate mycorrhizal symbionts in foreign soils may limit the success of tree migrations, and if so, to help us design practices that increase our success at facilitating changes in these forests.

Daniel adds: Some housecleaning bits to add. Dr. Simard noted that a version of today’s BPotD appeared in the Faculty of Forestry’s newsletter Branch Lines, here: Simard, S.W. (2010) Why research matters to the forest systems of BC (PDF). Branch Lines, 20: 4-5. Dr. Simard also contributed the photograph of Cantharellus formosus. The illustration of the fungi and tree is courtesy of Shannon Wright. The schematic of the fungal network is by Kevin Beiler, and was published in: Beiler KJ, Durall DM, Simard SW, Maxwell SA, Kretzer AM. 2010. Architecture of the wood-wide web: Rhizopogon spp genets link multiple Douglas-fir cohorts. New Phytologist, 185: 543-553.

Cantharellus formosus
Mycorrhizal Network by Shannon Wright
Network by Kevin Beiler

22 responses to “Mycorrhizal Networks”

  1. Meg Bernstein

    How fascinating! Just like Pandora, or vice versa?

  2. Jewell

    What goes on that we never see in the plant world is as fascinating as the beauty that we enjoy.

  3. annie Morgan

    My goodness, so much goes on underground! Most interesting.

  4. Sharon Mason

    This is beautiful and stunning evidence of how the unseen world exists whether we believe in it or not. Thank you for superb research. As a wild mushroom picker, I treasure the diversity of our North Cascades.

  5. Irma in Sweden

    This explains why the collecting of the lovely chanterelles is so like surfing the Internet. You just keep going along looking for the next fungi and all of a sudden you are far away from where you started. We had a old oak stump close to the house that provided a nice and plentiful catch each summer

  6. linda miller

    I thank you so much for this write up. I am going to share this with my Virginia Master Naturalist chapter.
    The graphic mapping hits the mark!
    Thank you…..Linda

  7. Bonnie

    This is fascinating! I’ve read about this kind of thing (in novels, usually science fiction), but have never seen a picture or map. Thank you!

  8. Lynne

    When I saw the movie “Avatar”, the world of Pandora and its interconnectedness reminded me immediately of this underground fungal network. Truth is not so far from fiction!

  9. elizabeth a airhart

    like others books poetry about nature
    alice in wonderland comes to mind
    and thelore of the tribes
    this is fine work thank you for shareing
    an old song i talk to the trees but they
    don’t listen to me from what i just
    read they are smarter and just do not care to

  10. Mike A

    I love mycorrhizae! Especially those that produce Chanterelles and Boletes. You should run a series on Myco-heterotrophs.

  11. Sara Rundle in Lead Mine, MO

    I live deep in the woods – and learning more about the interconnectedness of the fungi & the forest is fascinating. The natives are gearing up for mushroom hunting, it’s almost as big as deer season. As a recent immigrant from CA, I don’t know what I’m doing, but I still go out & look. Lots of different types of fungus, due to broken limbs, trees down from a big ice storm in 2007; there’s tons of cellulose debris out here. Your article also provides new insight into forestry management, I wonder if the principle would apply to oak trees. Great write up.

  12. Greg

    Fantastic. Older trees supporting younger trees like a mother hen with chicks and the relationship to birches very interesting and important research.

  13. M. D. Vaden

    Sure like the illustrations that were included.
    Its a remarkable part of nature.

  14. bev

    I haven’t been able to view this site for awhile, but, as always, berate myself for not doing it sooner when reading such fascinating articles! I will share this with my fellow public garden volunteeers!

  15. lisa

    Wonderful article. Thank you. The relationships between trees and mycorrhizal fungal mycelium have always enchanted and fascinated me. I wonder if anyone can tell me: Do any other plants (besides trees) engage in this sort of symbiotic relationship with mycorrhizal fungi? I know there are relationships with nitrogen-fixing bacteria happening in the legume family, but I’m curious about these networks of mycorrhizal fungi and other plants besides trees.

  16. John

    This is wonderful information. Is there a chance we can see a key that describes the different-colored lines and shading in the graphic?

  17. Mary Ann, in Toronto

    Very interesting to read some details about this!
    I agree with John, the map is great but it needs a legend.

  18. Daniel Mosquin

    I’ve asked Lindsay to contact Dr. Simard about it.

  19. Mark J in Portland ME

    Interesting about the carbon transport. My recent and limited literature review of MF had indicated their value in boosting nutrient uptake potential, and therefore being of value in poor soils conditions and reclamation sites for establishment of new vegetation. I would be interested in comment from others about the value of MF additives for planting soil mixes for landscape planting applications.

  20. Daniel Mosquin

    Here’s the caption for that figure:
    “The top-down spatial topology of Rhizopogon spp. genets and Douglas-fir trees in a 30 x 30 m plot. The plot (square outline) lies on a southeastern slope and contains 67 trees of various ages (green shapes; sized relative to each tree’s diameter). Small black dots mark Rhizopogon ectomycorrhiza sample locations (n = 401), 338 of which were associated with a specific tree and fungal genet based on microsatellite DNA analysis. Samples representative of each fungal genet are outlined in different colours. Rhizopogon vesiculosus genets (n = 14) are shaded with a blue background, and Rhizopogon vinicolor genets (n = 13) with pink. Lines illustrate the linkages between tree roots encountered in Rhizopogon ectomycorrhizas and corresponding source trees aboveground (‘root lengths’) and are coloured according to tree genotype. An arrow points to the most highly connected tree, which was linked to 47 other trees through eight R. vesiculosus genets and three R. vinicolor genets inside the plot. Some trees, mycorrhiza samples, and ⁄ or genets may be obscured by overlapping features.”

  21. Mary Ann, in Toronto

    Thank you for the caption. Remarkable!

  22. fotkin

    Very impressive! Just blogged about it in my blog:

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