This document summarizes the status of quantifying soil organic carbon (SOC) in northern permafrost zone soils. It discusses the challenges in measuring SOC in these regions due to unique cryogenic soil formation processes and variability. The Northern Circumpolar Soil Carbon Database was developed using over 1700 soil samples to estimate SOC to 1 meter depth, but does not include deeper estimates. Updated databases including over 500 deeper soil samples now provide SOC estimates to 3 meter depth. However, data remains limited relative to other global regions due to access challenges in remote Arctic areas.

1. Soil organic carbon in soils of the northern
permafrost zones: Information status and challenges
Agriculture and Agri-Food Canada
Summerland, British Columbia
Scott Smith and Bert VandenBygaart
Presentation to FAO SOC Symposium
Rome, March 22, 2017

2. Outline
1. Introduction- why is this important
2. The nature of SOC in permafrost-affected soils
3. The challenges of quantifying SOC in permafrost-
affected soils
4. Information products available
5. Recommendations

3. Schuur and Hugelius (2016) Terrestrial Carbon Cycle. Arctic Report Card.
 Northern permafrost zones soils contain up to 1800 Pg C m-2 to a depth of
100 cm, half of all terrestrial SOC, double amount in atmosphere.
 Warming conditions promote microbial conversation of permafrost C into
the greenhouse gases CO2 and CH4
 Overall tundra appears to be releasing net carbon to the atmosphere
 The magnitude and timing of greenhouse gas emissions from these regions
and their impact on changing climate remain highly uncertain

4. Source: Zubrzycki et al. 2014

5. The nature of SOC in permafrost-affected soils
 In the northern high-latitude regions, soil formation is governed by a
number of unique cryogenic processes (such as frost heave, cryoburbation
and thermokarst formation) .
 The roles of cold temperatures and ice formation are extremely important
for organic matter accumulation and re-distribution in soils.
 These processes can cause extreme variability in the size and distribution
of SOC stocks, particularly in soils underlain by permafrost (i.e. Cryosols).
 Permafrost is by definition ground that does not thaw during the summer,
under these conditions soils may contain large volumes of ice.

6. Figure source Mishra 2013
The nature of SOC in permafrost-affected soils

7. Source: Bockheim J G 2007 Importance of cryoturbation in redistributing
organic carbon in permafrost-affected soils Soil Sci. Soc. Am.
J. 71 1335–42:
The nature of SOC in permafrost-affected soils

8. Source: Zubrzycki et al. 2014
Cryoturbation processes mix and bury SOC
Source: Ping et al. 2015
Active layer
Earth Hummock
Ice Wedges

9. Source: Ping et al. 2010
Non-cryoturbated Cryoturbated
• It has been estimated that 19% of the soil area of the permafrost region (3.6 million
km2) is cryoturbated. (Mishray et al 2013)
• The impact of these features on the heterogeneity of SOC stocks needs to be
considered when upscaling to regional scale databases.

10. The amount of data is small relative to that available in other regions of the world
primarily due to logistical difficulties, extreme working conditions, and the cost
involved with accessing remote areas.
The soils in permafrost regions are under sampled, both spatially and vertically,
especially below the active layer
Existing databases vary considerably in terms of sampling depth and protocols,
analytical methods, and the overall reliability of the data (Hugelius and Kuhry
2009,Hugelius et al 2013).
Source: Mishra et al 2013; Vitharana et al 2015
Significant risks for biased conclusions exist due to inadequate and uneven
distributions of SOC profile observations in permafrost regions.
The Challenges in Quantifying SOC in Cryosolic Soils

11.  Permafrost regions hold between 1400 and 1850 Pg of SOC to a depth of over
300 cm, twice the mass of carbon found in the atmosphere and almost half of
all global soil carbon ,
 Stocks of SOC 0 - 30 cm are estimated at 200 Pg m-2,
 Stocks of SOC 0 - 100 cm is estimated at 500 Pg m-2

12. Source: Hugelius et al. (2013)
(1778 pedons for a 18.8 x 106 km2 land area).
The NCSCD was developed
by an international working
group composed of the best
cryopedologists from all
northern countries
particularly Canada, US and
Russia

13. SOC values scaled-up from
pedons to landscape using
component listings from
legacy soil survey maps

14. Grid cell published at 1 km2

15. Figure 1. Inconsistencies in SOC stocks (to 1 m depth) between observation-
based (Northern Circumpolar Soil Carbon Database) and baseline ESM estimates
calculated from the mean values in four CMIP5 models
Source: Mishra et al2013

16. Hengl, T., Mendes de Jesus, J., Heuvelink, G. B.M., Ruiperez Gonzalez, M., Kilibarda, M. et al. (2017) SoilGrids250m:
global gridded soil information based on Machine Learning. PLOS ONE 12(2): e0169748
Hengl T, de Jesus JM, MacMillan RA, Batjes NH, Heuvelink GBM, et al. (2014) SoilGrids1km — Global Soil
Information Based on Automated Mapping. PLoS ONE 9(8): e105992. doi:10.1371/journal.pone.0105992
Predictive (digital) mapping
using pedon inputs up-scaled
spatially using multivariate
statistics.
Reports on a full set of soil
attributes not just SOC
Soil Grids 250m is currently
undergoing validation in Canada,
including the permafrost region

17. Major constraint for both datasets in the northern circumpolar region is lack of data

18. Recommendations
As with organic (peat) soils, Cryosolic soils should be reported at both the 0 -
30 cm and 0-100 cm depth intervals due to the abundance of subsurface SOC
Both information products represent the best current data available for the
permafrost region – different methods and different expertise
It is unlikely there will be the time or enough new data to create better data
products for high latitude regions the FAO GSOC map…..so..
Countries should examine both data products and incorporate these into
their national maps as they best see fit.

19. Thank you for your attention

20. Source: Swanson et al. 2000

21. High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database
(NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of
18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional
soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to
calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the
northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been
no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC
storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m−2) in
deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm
(356 pedons) depth ranges.
The Northern Circumpolar Soil Organic Carbon Database
Hugelius, G., Tarnocai, C., Broll, G., Canadell, J. G., Kuhry, P., and Swanson, D. K.: The
Northern Circumpolar Soil Carbon Database: spatially distributed datasets of soil
coverage and soil carbon storage in the northern permafrost regions, Earth Syst. Sci.
Data, 5, 3-13, doi:10.5194/essd-5-3-2013, 2013.

22. The nature of SOC in permafrost-affected soils
Surface carbon is buried by
various processes including
these common to all soil
But in permafrost regions
buried carbon is disrupted by
cryogenic processes and
ultimately preserved through
freezing
Sources: Chaoprichaa and Marín-Spiottaa, 2013;

23. Machine learning from existing pedon data