期刊
GLOBAL CHANGE BIOLOGY
卷 20, 期 2, 页码 641-652出版社
WILEY
DOI: 10.1111/gcb.12417
关键词
Alaska; boreal forest; C decomposition; climate change; Siberia; soil organic carbon; tundra
资金
- NSF Bonanza Creek LTER
- NSF CAREER Program
- Department of Energy NICCR
- Department of Energy TES
- U.S. National Parks
- Inventory Monitoring Program
- Danish National Research Foundation [CENPERM DNRF100]
- European Union FP7-ENVIRONMENT project PAGE21
- National Science Foundation Vulnerability of Permafrost Carbon Research Coordination Network [955713]
- Direct For Biological Sciences
- Emerging Frontiers [1065587] Funding Source: National Science Foundation
- Directorate For Geosciences
- Office of Polar Programs (OPP) [1107707] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [0955713] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [0955341, 1026415] Funding Source: National Science Foundation
High-latitude ecosystems store approximately 1700Pg 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 (>1year) 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 degrees 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 degrees C of fast cycling C typically was below 1year, between 5 and 15years for slow turning over C, and more than 500years 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 degrees 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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