Chien-Lu Ping et al.: High stocks of soil organic carbon in the North American Arctic region

Nature Geoscience
Published online: 24 August 2008 | doi:10.1038/ngeo284

High stocks of soil organic carbon in the North American Arctic region

Chien-Lu Ping¹, Gary J. Michaelson¹, Mark T. Jorgenson², John M. Kimble³, Howard Epstein⁴, Vladimir E. Romanovsky⁵ & Donald A. Walker⁶

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Abstract

The Arctic soil organic-carbon pool is a significant, but poorly constrained, carbon store. The most cited pool size estimates are based on a study that severely undersamples Arctic soils, with only five out of the 48 soils examined actually from the Arctic region. Furthermore, previous measurements have been confined to the top 40 cm of soil. Here, we present 1-m-deep measurements of soil organic carbon obtained at 117 locations in the North American Arctic region. To this dataset we add previously published measurements to generate a total sample size of 139 North American Arctic soils. We show that soil organic-carbon stores are highly dependent on landscape type, being highest in lowland and hilly upland soils, where values average 55.1 and 40.6 kg soil organic carbon m^-2 respectively, and lowest in rubbleland and mountain soils, where values average 3.4 and 3.8 kg soil organic carbon m^-2, respectively. Extrapolating our measurements using known distributions of landscape types we estimate that the total organic carbon pool in North American Arctic soils, together with the average amount of carbon per unit area, is considerably higher than previously thought. Our estimates of the depth distribution and total amount of organic carbon in North American Arctic soils will form an important basis for studies examining the impact of climate warming on CO₂ release in the region.

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1. Agriculture and Forestry Experiment Station, University of Alaska Fairbanks, 533 E. Fireweed, Palmer, Alaska 99645, USA
2. Alaska Biological Research, Box 80410, Fairbanks, Alaska 99708, USA
3. Professional Soil Scientist, 151 East Hill Church Road, Addison, New York 14801, USA
4. Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, Virginia 22904, USA
5. Geophysical Institute, University of Alaska Fairbanks, PO Box 755780, Fairbanks, Alaska 99775, USA
6. Institute of Arctic Biology, University of Alaska Fairbanks, PO Box 757000, Fairbanks, Alaska 99775, USA

Correspondence to: Chien-Lu Ping¹ e-mail: ffcp@uaf.edu