Circumpolar assessment of permafrost C quality and its vulnerability over time using long-term incubation data Journal Article


Authors: Schaedel, Christina; Schuur, Edward A. G.; Bracho, Rosvel; Elberling, Bo; Knoblauch, Christian; Lee, Hanna; Luo, Yiqi; Shaver, Gaius R.; Turetsky, Merritt R.
Article Title: Circumpolar assessment of permafrost C quality and its vulnerability over time using long-term incubation data
Abstract: 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 (gt;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.
Keywords: TURNOVER; DECOMPOSITION; boreal forest; TUNDRA; ALASKA; climate change; CLIMATE-CHANGE; CO2; FOREST; peat; soil organic carbon; SOIL ORGANIC-MATTER; SIBERIA; TUNDRA SOILS; TEMPERATURE SENSITIVITY; CARBON RELEASE; C decomposition
Journal Title: Global Change Biology
Volume: 20
Issue: 2
ISSN: 1354-1013
Publisher: Blackwell Publishing  
Publication Place: HOBOKEN; 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Date Published: 2014
Start Page: 641
End Page: 652
DOI/URL:
Notes: PT: J; TC: 0; UT: WOS:000329349700028