Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowground fungal communities is largely unknown. We sought to test if (H1) fungal community spatial structure matched aboveground forest structure, (H2) fungal functional guilds exhibited differential associations to aboveground tree, snag, and deadwood, and (H3) that large-diameter trees and snags have a larger influence on fungal community richness than smaller-diameter trees. We used MiSeq sequencing of fungal communities collected from soils in a spatially intensive survey in a portion of Cedar Breaks National Monument, Utah, USA. We used random forest models, to explore the spatial structure of fungal communities as they relate to explicitly mapped trees and deadwood distributed across 1.15 ha of a 15.32 ha mapped subalpine forest.

Results: We found 6,177 fungal amplicon sequence variants across 117 sequenced samples. Tree diameter, deadwood presence, and tree species identity explained more than twice as much variation (38.7% vs. 10.4%) for ectomycorrhizal composition and diversity than for the total or saprotrophic fungal communities. Species identity and distance to the nearest large-diameter tree (≥ 40.2 cm) were better predictors of fungal diversity than were the identity and distance to the nearest tree. Soil nutrients, topography, and tree species differentially influenced the composition and diversity of each fungal guild. Locally rare tree species had outsized influence on fungal community richness.

Conclusions: These results highlight that fungal guilds are differentially associated with the location, size, and species of aboveground trees. Large-diameter trees are implicated as drivers of belowground fungal diversity, particularly for ectomycorrhizal fungi.

Author ORCID Identifier

Joseph D. Birch

James A. Lutz

Soren Struckman

Jessica Miesel

Justine Karst

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Natural Science and Engineering Council of Canada

Utah Agricultural Experiment Station


Utah State University

Award Number

Utah Agricultural Experiment Station 153, 1398 and 1423


Soil samples were taken in a ordered grid across 1.15ha and environmental DNA was extracted for amplification. The ITS2 region was amplified to identify fungal communities of each root and soil sample. Fungal sequences were quality filtered and rarefied to 90% of the minimum read abundance.

Scientfic Names

Abies bifolia, Populus tremuloides, Picea pungens, Picea engelmannii, Pinus longaeva, Pinus flexilis, Pseudotsuga menziesii

Referenced by

Birch, J.D., Lutz, J.A., Struckman, S., Miesel, J.R., and J. Karst. (2023). Large-diameter trees and deadwood correspond with belowground ectomycorrhizal fungal richness. Ecological Processes.

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Research was performed under annual (2014–2020) National Park Service research permits for study CEBR-00016 and study CEBR-00020 (2018–2019).


Forest Sciences | Plant Sciences


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This work is licensed under a Creative Commons Attribution 4.0 License.




Additional Files

Data_for_Gridding_Metadata.txt (5 kB)
MD5: d5938ed548ecb8b23aa83de45cc9389f

GRID_Fungi_data.xlsx (2892 kB)
MD5: 06a837cfd7948a4b93a5efa0bf60fb36


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