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Contributed Talk

Session: : Rhizosphere And Root Function 2

COS 224-3 - Partitioning root, mycorrhizal, and heterotrophic respiration within monodominant stands of phylogenetically and functionally diverse temperate trees

Wednesday, August 9, 2023
4:00 PM – 4:15 PM PDT
Location: B119

    Presenting Author(s)

  • ML

    Marvin Lo

    Research Assistant
    The Morton Arboretum
    Lisle, Illinois, United States

    • Coauthor(s)

  • IV

    Isabella Vergara

    The Morton Arboretum, United States

  • KP

    Kelsey R. Patrick

    Research Aide
    The Morton Arboretum
    Montgomery, Illinois, United States

  • JW

    Jeffrey M. Warren

    Oak Ridge National Laboratory
    Oak Ridge, TN, United States

  • MM

    M. Luke McCormack

    PI (head) of the Arboretum’s root ecology lab
    The Morton Arboretum
    Lisle, Illinois, United States

Abstract: Soil respiration is a major component of carbon cycling and is key to understanding net carbon exchange between terrestrial ecosystems and the atmosphere. However, within a forest ecosystem the contributions of roots, associated mycorrhizal fungi, and free-living soil heterotrophs to total soil respiration remain poorly understood. In particular, sensitivity of each component of soil respiration to seasonal changes in edaphic conditions (e.g., temperature and moisture) are not well documented across different forest types. In this study, we assessed the components of soil respiration in 10 different mature monodominant tree stands in Northern Illinois that encompass wide phylogenetic and functional diversity including angiosperms and gymnosperms; ecto- and arbuscular mycorrhizal associations; and deciduous and evergreen growth habits. Using root and mycorrhizal exclusion techniques allowed for quantification of constituent components of total soil respiration from each stand throughout the 2022 growing season. Overall peak total soil respiration occurred during late June to early July; however, the timing of peak root, mycorrhizal, and heterotrophic respiration did not necessarily occur at the same time, and varied across the different tree species. In general, heterotrophic respiration was the dominant component of total soil respiration throughout the growing season, with individual contributions from roots, mycorrhizae and soil heterotrophs being 27%, 17%, and 56%, respectively. Although heterotrophic respiration was dominant, rates were highly variable among plots; e.g., Carya ovata and Chamaecyparis pisifera plots had similar or higher levels of mycorrhizal respiration relative to heterotrophic respiration. Understanding the patterns of total soil carbon dioxide (CO2) efflux contributions from each soil component and their sensitivity to seasonal and edaphic conditions provides useful mechanistic information for predicting regional or global changes in soil carbon dynamics for forest ecosystems.