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

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, 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. 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. 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. Finally, 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.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst. and Environmental Sciences Division
  2. USDA Forest Service, Houghton, MI (United States). Northern Research Station
  3. USDA Forest Service, Grand Rapids, MI (United States). Northern Research Station
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Accelerator Mass Spectrometry
Publication Date:
Report Number(s):
LLNL-JRNL-691084
Journal ID: ISSN 0032-079X; 62794
Grant/Contract Number:
AC05-00OR22725; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Plant and Soil
Additional Journal Information:
Journal Volume: 424; Journal Issue: 1-2; Journal ID: ISSN 0032-079X
Publisher:
Springer
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; Fine roots; Nutrient availability; Peatlands; Rooting depth distribution; Root growth; Root peak standing crop; 60 APPLIED LIFE SCIENCES
OSTI Identifier:
1376311
Alternate Identifier(s):
OSTI ID: 1438624