A New Data Set for Estimating Organic Carbon Storage to 3 M Depth in Soils of the Northern Circumpolar Permafrost Region
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Earth Syst. Sci. Data, 5, 393–402, 2013 Earth System www.earth-syst-sci-data.net/5/393/2013/ Science doi:10.5194/essd-5-393-2013 © Author(s) 2013. CC Attribution 3.0 License. Open Access Open Data A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region G. Hugelius1, J. G. Bockheim2, P. Camill3, B. Elberling4,5, G. Grosse6, J. W. Harden7, K. Johnson8, T. Jorgenson9, C. D. Koven10, P. Kuhry1, G. Michaelson11, U. Mishra12, J. Palmtag1, C.-L. Ping11, J. O’Donnell13, L. Schirrmeister14, E. A. G. Schuur15, Y. Sheng16, L. C. Smith16, J. Strauss14, and Z. Yu17 1Department of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm, Sweden 2Department of Soil Science, University of Wisconsin, Madison, WI 53706-1299, USA 3Earth and Oceanographic Science Department and Environmental Studies Program, Bowdoin College, Brunswick, ME 04011, USA 4CENPERM (Center for Permafrost), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark 5UNIS, The University Centre in Svalbard, Longyearbyen, Norway 6Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, AK 99775, USA 7US Geological Survey, Menlo Park, CA 94025, USA 8US Forest Service, Newtown Square, PA 29008, USA 9Alaska Ecoscience, 2332 Cordes Way, Fairbanks, AK 99709, USA 10Lawrence Berkeley National Lab, Berkeley, CA, USA 11Palmer Research Center, University of Alaska Fairbanks, 1509 S. Georgeson Drive, Palmer, AK 99645, USA 12Environmental Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA 13Arctic Network, National Park Service, 4175 Geist Rd. Fairbanks, AK 99709, USA 14Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Periglacial Research Unit Potsdam, Telegrafenberg A43, 14473 Potsdam, Germany 15Department of Biology, University of Florida, Gainesville, FL 32611, USA 16Department of Geography, University of California, Los Angeles (UCLA), Los Angeles, CA 90095-1524, USA 17Department of Earth and Environmental Sciences, Lehigh University, 1 West Packer Avenue, Bethlehem, PA 18015, USA Correspondence to: G. Hugelius ([email protected]) Received: 6 March 2013 – Published in Earth Syst. Sci. Data Discuss.: 25 April 2013 Revised: 1 November 2013 – Accepted: 4 November 2013 – Published: 23 December 2013 Abstract. High-latitude terrestrial ecosystems are key com- classification maps together with pedon data from the north- ponents in the global carbon cycle. The Northern Circumpo- ern permafrost region. Previously, the NCSCD has been used lar Soil Carbon Database (NCSCD) was developed to quan- to calculate SOC storage to the reference depths 0–30 cm and tify stocks of soil organic carbon (SOC) in the northern cir- 0–100 cm (based on 1778 pedons). It has been shown that cumpolar permafrost region (a total area of 18.7 × 106 km2). soils of the northern circumpolar permafrost region also con- The NCSCD is a geographical information system (GIS) data tain significant quantities of SOC in the 100–300 cm depth set that has been constructed using harmonized regional soil range, but there has been no circumpolar compilation of Published by Copernicus Publications. 394 G. Hugelius et al.: A new data set for estimating organic carbon storage pedon data to quantify this deeper SOC pool and there are no was based on limited field data of 46 pedons, and was not in- spatially distributed estimates of SOC storage below 100 cm cluded in the first version of the spatially distributed NCSCD. depth in this region. Here we describe the synthesis of an The estimated SOC pool in deeper (> 300 cm) Yedoma de- updated pedon data set for SOC storage (kg C m−2) in deep posits (407 Pg) and deltaic deposits (241 Pg) brings the total soils of the northern circumpolar permafrost regions, with estimate to 1672 Pg, of which 1466 Pg is stored in perenni- separate data sets for the 100–200 cm (524 pedons) and 200– ally frozen ground (Tarnocai et al., 2009). This is about twice 300 cm (356 pedons) depth ranges. These pedons have been as much C as in the atmosphere (Houghton, 2007). grouped into the North American and Eurasian sectors and While it is recognized that the SOC pool stored in per- the mean SOC storage for different soil taxa (subdivided mafrost regions is very large and vulnerable to remobiliza- into Gelisols including the sub-orders Histels, Turbels, Or- tion through permafrost thaw (Elberling et al., 2013), pool thels, permafrost-free Histosols, and permafrost-free min- estimates are poorly constrained and quantitative error es- eral soil orders) has been added to the updated NCSCDv2. timates are lacking (Hugelius, 2012). Tarnocai et al. (2009) The updated version of the data set is freely available on- assigned qualitative levels of confidence for different compo- line in different file formats and spatial resolutions that en- nents of the circumpolar SOC estimate. The deep soil (100– able spatially explicit applications in GIS mapping and ter- 300 cm) estimate was assigned the lowest degree of confi- restrial ecosystem models. While this newly compiled data dence (low to very low) because of a lack of field data and set adds to our knowledge of SOC in the 100–300 cm depth limited spatial representativeness. range, it also reveals that large uncertainties remain. Identi- Here we describe the compilation of an updated pedon fied data gaps include spatial coverage of deep (> 100 cm) data set for describing SOC storage (kg C m−2) in deep soils pedons in many regions as well as the spatial extent of areas of the northern circumpolar permafrost regions. The new data with thin soils overlying bedrock and the quantity and distri- set provides separate estimates for the 100–200 cm and 200– bution of massive ground ice. An open access data-portal for 300 cm depth ranges, and represents a significant increase in the pedon data set and the GIS-data sets is available online the amount of available pedons compared to the previous es- at http://bolin.su.se/data/ncscd/. The NCSCDv2 data set has timate (increase by factors 11 and 8 for the two depth ranges, a digital object identifier (doi:10.5879/ECDS/00000002). respectively). This data set has been integrated with the NC- SCD (Hugelius et al., 2013) to enable upscaling and calcu- lation of regional and circumpolar SOC stocks. The updated 1 Introduction NCSCDv2 is freely available online in several different file formats and spatial resolutions that enable its applications in High latitude terrestrial ecosystems are considered key com- geographical information system (GIS) mappings and terres- ponents in the global carbon (C) cycle (McGuire et al., 2009). trial ecosystem models. In these regions, low temperatures and high soil-water con- tents reduce decomposition rates (Davidson and Janssens, 2006) and fire combustion losses (Harden et al., 2000). Im- 2 Data set structure portant processes of soil organic C (SOC) accumulation in- clude peat formation, sustained accumulation of syngenetic We used the following two criteria to evaluate georeferenced sedimentary deposits and burial of SOC through cryotur- pedon data for inclusion into the updated data set. (1) Pedon bation (Ping et al., 1998; Tarnocai and Stolbovoy, 2006; described following a classification system suitable for per- Schirrmeister et al., 2011).Together this has resulted in an mafrost affected soils, e.g., US Soil Taxonomy, The Cana- accumulation of large stocks of SOC in permafrost min- dian System of Soil Classification or the World Reference eral soils, organic soils, deltaic deposits and ice-rich, late Base for soil resources (Soil Survey Staff, 1999; Soil Classi- Pleistocene silty deposits (Yedoma) (Schuur et al., 2008). fication Working Group, 1998; IUSS Working Group WRB, If widespread permafrost thaw occurs, SOC that was previ- 2007). (2) Data available on percentage organic C (OC %), ously protected in permafrost may be mineralized leading to percentage coarse fragments (> 2 mm diameter) and/or seg- increased greenhouse gas fluxes to the atmosphere (Grosse et regated ice content (percentage weight) and dry bulk density al., 2011; Schuur et al., 2013). (BD) of described soil horizons down to sufficient soil depths Using the Northern Circumpolar Soil Carbon Database (≥ 150 cm, see Sect. 2.1 below). (NCSCD; see Hugelius et al., 2013 for a full technical de- Data sources include pedons from previously published scription of the data set), Tarnocai et al. (2009) estimated scientific studies, existing databases and previously unpub- the SOC pool to be 191 Pg (1 Pg = 1012 kg) for topsoil (0– lished material (all original data sources are provided in the 30 cm depth) and 496 Pg for the upper 100 cm of soil in pedon data set spreadsheet). The compiled data set follows the northern circumpolar permafrost region (a total area of the US Soil Taxonomy classification. The data set is subdi- 18.7 × 106 km2 as estimated by Brown et al., 1997). The vided into the following classes: the three sub-orders of the SOC pool to 300 cm soil depth was estimated to be 1024 Pg Gelisol soil order (Histels, Turbels and Orthels) as separate (Tarnocai et al., 2009). This estimate of SOC to 300 cm depth classes, the Histosol soil order as a separate class and, lastly, Earth Syst. Sci. Data, 5, 393–402, 2013 www.earth-syst-sci-data.net/5/393/2013/ G. Hugelius et al.: A new data set for estimating organic carbon storage 395 all remaining soil orders (non-permafrost mineral soil or- umetric ice content was used in permafrost soil horizons, ders) grouped as one class. Peat cores from the West Siberian based on measured ice content data. Lowland (Smith et al., 2012, supplementary online material, n = 102) that are located within the northern circumpolar per- 2.1.2 Extrapolation and estimates based on default mafrost region were also used in the study.