Fine-root turnover patterns and their relationship to root diameter and soil depth in a 14C-labeled hardwood forest
- University of California, Santa Cruz
- Lawrence Berkeley National Laboratory (LBNL)
- ORNL
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 ?14C 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 ?14C 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.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge National Environmental Research Park
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 930812
- Journal Information:
- New Phytologist, Vol. 172, Issue 3; ISSN 0028-646X
- Country of Publication:
- United States
- Language:
- English
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