Towards a global harmonized permafrost soil organic carbon stock estimates.

Thursday, December 14, 2017 - 08:00
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Permafrost affected soils store disproportionately large amount of organic carbon stocks due to multiple cryopedogenic processes. Previous permafrost soil organic carbon (SOC) stock estimates used a variety of approaches and reported substantial uncertainty in SOC stocks of permafrost soils. Here, we used spatially referenced data of soil-forming factors (topographic attributes, land cover types, climate, and bedrock geology) and SOC pedon description data (n = 2552) in a regression kriging approach to predict the spatial and vertical heterogeneity of SOC stocks across the Northern Circumpolar and Tibetan permafrost regions. Our approach allowed us to take into account both environmental correlation and spatial autocorrelation to separately estimate SOC stocks and their spatial uncertainties (95% CI) for three depth intervals at 250 m spatial resolution. In Northern Circumpolar region, our results show 1278.1 (1009.33 – 1550.45) Pg C in 0-3 m depth interval, with 542.09 (451.83 – 610.15), 422.46 (306.48 – 550.82), and 313.55 (251.02 – 389.48) Pg C in 0 – 1, 1 – 2, and 2 – 3 m depth intervals, respectively. In Tibetan region, our results show 26.68 (9.82 – 79.92) Pg C in 0 – 3 m depth interval, with 13.98 (6.2 – 32.96), 6.49 (1.73 – 25.86), and 6.21 (1.889 – 20.90) Pg C in 0 – 1, 1 – 2, and 2 – 3 m depth intervals, respectively. Our estimates show large spatial variability (50 – 100% coefficient of variation, depending upon the study region and depth interval) and higher uncertainty range in comparison to existing estimates. We will present the observed controls of different environmental factors on SOC at the AGU meeting.

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