Architecture of the wood-wide web: Rhizopogon spp. genets link multiple Douglas-fir cohorts

Authors

  • Kevin J. Beiler,

    1. Biology and Physical Geography Unit and SARAHS Centre, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
    2. Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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  • Daniel M. Durall,

    1. Biology and Physical Geography Unit and SARAHS Centre, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
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  • Suzanne W. Simard,

    1. Department of Forest Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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  • Sheri A. Maxwell,

    1. Department of Biology, University of Western Ontario, London, ON N6A 5B8, Canada
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  • Annette M. Kretzer

    1. SUNY College of Environmental Science and Forestry, Faculty of Environmental and Forest Biology, One Forestry Drive, Syracuse, NY 13210-2788, USA
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Author for correspondence:
Kevin J. Beiler
Tel: +1 250 826 1002
Email: Kevin.Beiler@gmail.com

Summary

  • The role of mycorrhizal networks in forest dynamics is poorly understood because of the elusiveness of their spatial structure. We mapped the belowground distribution of the fungi Rhizopogon vesiculosus and Rhizopogon vinicolor and interior Douglas-fir trees (Pseudotsuga menziesii var. glauca) to determine the architecture of a mycorrhizal network in a multi-aged old-growth forest.
  • Rhizopogon spp. mycorrhizas were collected within a 30 × 30 m plot. Trees and fungal genets were identified using multi-locus microsatellite DNA analysis. Tree genotypes from mycorrhizas were matched to reference trees aboveground. Two trees were considered linked if they shared the same fungal genet(s).
  • The two Rhizopogon species each formed 13–14 genets, each colonizing up to 19 trees in the plot. Rhizopogon vesiculosus genets were larger, occurred at greater depths, and linked more trees than genets of R. vinicolor. Multiple tree cohorts were linked, with young saplings established within the mycorrhizal network of Douglas-fir veterans. A strong positive relationship was found between tree size and connectivity, resulting in a scale-free network architecture with small-world properties.
  • This mycorrhizal network architecture suggests an efficient and robust network, where large trees play a foundational role in facilitating conspecific regeneration and stabilizing the ecosystem.

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