Fine-root turnover patterns and their relationship to root diameter and soil depth in a 14C-labeled hardwood forest

J. D. Joslin, J. B. Gaudinski, M. S. Torn, W. J. Riley, P. J. Hanson

Research output: Contribution to journalArticlepeer-review

171 Scopus citations

Abstract

• Characterization of turnover times of fine roots is essential to understanding patterns of carbon allocation in plants and describing forest C cycling. We used the rate of decline in the ratio of 14C to 12C in a mature hardwood forest, enriched by an inadvertent 14C pulse, to investigate fine-root turnover and its relationship with fine-root diameter and soil depth. • Biomass and Δ14C values were determined for fine roots collected during three consecutive winters from four sites, by depth, diameter size classes (< 0.5 or 0.5-2 mm), and live-or-dead status. • Live-root pools retained significant 14C enrichment over 3 yr, demonstrating a mean turnover time on the order of years. However, elevated Δ14C values in dead-root pools within 18 months of the pulse indicated an additional component of live roots with short turnover times (months). Our results challenge assumptions of a single live fine-root pool with a unimodal and normal age distribution. • Live fine roots < 0.5 mm and those near the surface, especially those in the O horizon, had more rapid turnover than 0.5-2 mm roots and deeper roots, respectively.

Original languageEnglish
Pages (from-to)523-535
Number of pages13
JournalNew Phytologist
Volume172
Issue number3
DOIs
StatePublished - Nov 2006

Keywords

  • C
  • Carbon cycling
  • Fine-root lifespan
  • Fine-root turnover
  • Live fine-root turnover time
  • Root biomass
  • Root diameter
  • Root mortality

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