Circumpolar assessment of permafrost C quality and its vulnerability over time using long-term incubation data
High‐latitude ecosystems store approximately 1700 Pg of soil carbon (C), which is twice as much C as is currently contained in the atmosphere. Permafrost thaw and subsequent microbial decomposition of permafrost organic matter could add large amounts of C to the atmosphere, thereby influencing the g...
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Published in | Global change biology Vol. 20; no. 2; pp. 641 - 652 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Blackwell Publishing Ltd
01.02.2014
Wiley-Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | High‐latitude ecosystems store approximately 1700 Pg of soil carbon (C), which is twice as much C as is currently contained in the atmosphere. Permafrost thaw and subsequent microbial decomposition of permafrost organic matter could add large amounts of C to the atmosphere, thereby influencing the global C cycle. The rates at which C is being released from the permafrost zone at different soil depths and across different physiographic regions are poorly understood but crucial in understanding future changes in permafrost C storage with climate change. We assessed the inherent decomposability of C from the permafrost zone by assembling a database of long‐term (>1 year) aerobic soil incubations from 121 individual samples from 23 high‐latitude ecosystems located across the northern circumpolar permafrost zone. Using a three‐pool (i.e., fast, slow and passive) decomposition model, we estimated pool sizes for C fractions with different turnover times and their inherent decomposition rates using a reference temperature of 5 °C. Fast cycling C accounted for less than 5% of all C in both organic and mineral soils whereas the pool size of slow cycling C increased with C : N. Turnover time at 5 °C of fast cycling C typically was below 1 year, between 5 and 15 years for slow turning over C, and more than 500 years for passive C. We project that between 20 and 90% of the organic C could potentially be mineralized to CO2 within 50 incubation years at a constant temperature of 5 °C, with vulnerability to loss increasing in soils with higher C : N. These results demonstrate the variation in the vulnerability of C stored in permafrost soils based on inherent differences in organic matter decomposability, and point toward C : N as an index of decomposability that has the potential to be used to scale permafrost C loss across landscapes. |
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Bibliography: | Department of Energy NICCR and TES U.S. National Parks and Inventory Monitoring Program ark:/67375/WNG-FTSTFCWB-5 Figure S1. Observed and modeled respiration rates for five randomly selected soil samples (a-e). The samples are the same as in Table S3. Table S1. Soil sample parameters for each individual soil core. Table S2. Prior parameter range for C pool partitioning coefficients (fi) and decay rates (ki). Table S3. Comparison of data-model fit and C loss for three time frames using a 2-pool and a 3-pool model for five randomly selected soil samples. Table S4. Correlations between model parameters. Table S5. MLE (97.5% CI) for all parameters and potential C loss for 1, 10, and 50 incubations years for all 121 soil samples. Table S6. Multiple regression results for estimated parameters and C loss (MLE, upper and lower limit of 97.5% CI) for 50 incubation years at 5 °C. NSF CAREER Program Danish National Research Foundation - No. CENPERM DNRF100 NSF Bonanza Creek LTER National Science Foundation Vulnerability of Permafrost Carbon Research Coordination Network - No. 955713 istex:3EA6E3F6248D9FA2CE5EEBC18ED0E19E47AF1145 European Union FP7-ENVIRONMENT - No. GA282700 ArticleID:GCB12417 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1354-1013 1365-2486 |
DOI: | 10.1111/gcb.12417 |