Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

Colleen M. Iversen, Joanne Childs, Richard J. Norby, Todd A. Ontl, Randall K. Kolka, Deanne J. Brice, Karis J. McFarlane, Paul J. Hanson

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Background and aims: Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. We aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. Methods: We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. Results: The fine roots of trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Conclusions: The dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.

Original languageEnglish
Pages (from-to)123-143
Number of pages21
JournalPlant and Soil
Volume424
Issue number1-2
DOIs
StatePublished - Mar 1 2018

Funding

Acknowledgments We thank Arielle Garrett, Abra Martin, Ingrid Slette, Holly Vander Stel, A. Shafer Powell, Lisa Keller, Jonathan Brooks, Avni Malhotra, M. Luke McCormack, W. Robert Nettles, Merritt Turetsky, and Les Hook. The Spruce and Peatland Responses Under Climatic and Environmental change (SPRUCE) experiment is supported by the Office of Biological and Environmental Research in the United States Department of Energy’s Office of Science. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. A portion of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). We thank Arielle Garrett, Abra Martin, Ingrid Slette, Holly Vander Stel, A. Shafer Powell, Lisa Keller, Jonathan Brooks, Avni Malhotra, M. Luke McCormack, W. Robert Nettles, Merritt Turetsky, and Les Hook. The Spruce and Peatland Responses Under Climatic and Environmental change (SPRUCE) experiment is supported by the Office of Biological and Environmental Research in the United States Department of Energy’s Office of Science. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. A portion of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

FundersFunder number
DOE Public Access Plan
Office of Biological and Environmental Research in the United States Department of Energy
United States Government
U.S. Department of Energy
Office of ScienceDE-AC05-00OR22725
Lawrence Livermore National LaboratoryDE-AC52-07NA27344

    Keywords

    • Fine roots
    • Nutrient availability
    • Peatlands
    • Root growth
    • Root peak standing crop
    • Rooting depth distribution

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