Fine-root mortality rates in a temperate forest: estimates using radiocarbon data and numerical modeling.
* We used an inadvertent whole-ecosystem 14C label at a temperate forest in Oak Ridge, Tennessee, USA to develop a model (Radix1.0) of fine-root dynamics. Radix simulates two live-root pools, two dead-root pools, non-normally distributed root mortality turnover times, a stored carbon (C) pool, and seasonal growth and respiration patterns. * We applied Radix to analyze measurements from two root size classes (< 0.5 and 0.5-2.0 mm diameter) and three soil-depth increments (O horizon, 0-15 cm and 30-60 cm). * Predicted live-root turnover times were < 1 yr and approximately 10 yr for short- and long-lived pools, respectively. Dead-root pools had decomposition turnover times of approximately 2 yr and approximately 10 yr. Realistic characterization of C flows through fine roots requires a model with two live fine-root populations, two dead fine-root pools, and root respiration. These are the first fine-root turnover time estimates that take into account respiration, storage, seasonal growth patterns, and non-normal turnover time distributions. * The presence of a root population with decadal turnover times implies a lower amount of belowground net primary production used to grow fine-root tissue than is currently predicted by models with a single annual turnover pool.
Riley
W J
WJ
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Gaudinski
J B
JB
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.|Department of Environmental Studies, University of California, Santa Cruz, CA, USA.|Department of Integrative Biology, University of California, Berkeley, CA, USA.
Torn
M S
MS
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.|Energy and Resources Group, University of California, Berkeley, CA, USA.
Joslin
J D
JD
Belowground Forest Research, Apartado 104-5655, Santa Elena de Monteverde, Puntarenas, Costa Rica.
Hanson
P J
PJ
Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D019069:Cell Respiration; D017753:Ecosystem; D007553:Isotope Labeling / Q000379:methods; D008954:Models, Biological; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D012621:Seasons; D013714:Tennessee; D013997:Time Factors; D014197:Trees / Q000254:growth & development* / Q000378:metabolism
D002247:Carbon Isotopes; D002244:Carbon
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