Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Landscape partitioning and burial processes of soil organic carbon in contrasting areas of continuous permafrost
Stockholm University, Faculty of Science, Department of Physical Geography.
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Recent studies have shown that permafrost soils in the northern circumpolar region store almost twice as much carbon as the atmosphere. Since soil organic carbon (SOC) pools have large regional and landscape-level variability, detailed SOC inventories from across the northern permafrost region are needed to assess potential remobilization of SOC with permafrost degradation and to quantify the permafrost carbon-climate feedback on global warming.

This thesis provides high-resolution data on SOC storage in five study areas located in undersampled regions of the continuous permafrost zone (Zackenberg in NE Greenland; Shalaurovo and Cherskiy in NE Siberia; Ary-Mas and Logata in Taymyr Peninsula). The emphasis throughout the five different study areas is put on SOC partitioning within the landscape and soil horizon levels as well as on soil forming processes under periglacial conditions. Our results indicate large differences in mean SOC 0–100 cm storage among study areas, ranging from 4.8 to 30.0 kg C m-2, highlighting the need to consider numerous factors as topography, geomorphology, land cover, soil texture, soil moisture, etc. in the assessment of landscape-level and regional SOC stock estimates.

In the high arctic mountainous area of Zackenberg, the mean SOC storage is low due to the high proportion of bare grounds. The geomorphology based upscaling resulted in a c. 40% lower estimate compared to a land cover based upscaling (4.8 vs 8.3 kg C m-2, respectively). A landform approach provides a better tool for identifying hotspots of SOC burial in the landscape, which in this area corresponds to alluvial fan deposits in the foothills of the mountains. SOC burial by cryoturbation was much more limited and largely restricted to soils in the lower central valley. In the lowland permafrost study areas of Russia the mean SOC 0–100 cm storage ranged from 14.8 to 30.0 kg C m-2. Cryoturbation is the main burial process of SOC, storing on average c. 30% of the total landscape SOC 0–100 cm in deeper C-enriched pockets in all study areas. In Taymyr Peninsula, the mean SOC storage between the Ary-Mas and Logata study areas differed by c. 40% (14.8 vs 20.8 kg C m-2, respectively). We ascribe this mainly to the finer soil texture in the latter study area. Grain size analyses show that cryoturbation is most prominent in silt loam soils with high coarse silt to very fine sand fractions. However, in profiles and samples not affected by C-enrichment, C concentrations and densities were higher in silt loam soils with higher clay to medium silt fractions.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography, Stockholm University , 2017.
Series
Dissertations from the Department of Physical Geography, ISSN 1653-7211 ; 61
Keyword [en]
soil organic carbon, total nitrogen, permafrost, cryoturbation, geomorphology, land cover classification, slope processes, texture, upscaling, carbon/nitrogen ratio
National Category
Physical Geography Climate Research
Research subject
Physical Geography
Identifiers
URN: urn:nbn:se:su:diva-136383ISBN: 978-91-7649-610-7 (print)ISBN: 978-91-7649-611-4 (print)OAI: oai:DiVA.org:su-136383DiVA, id: diva2:1062344
Public defence
2017-02-10, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
European Science Foundation (ESF), 282700EU, FP7, Seventh Framework Programme, 282700Nordic Council of Ministers, 23001
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2017-01-18 Created: 2016-12-05 Last updated: 2018-01-13Bibliographically approved
List of papers
1. Controls on the storage of organic carbon in permafrost soil in northern Siberia
Open this publication in new window or tab >>Controls on the storage of organic carbon in permafrost soil in northern Siberia
Show others...
2016 (English)In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 67, no 4, p. 478-491Article in journal (Refereed) Published
Abstract [en]

This research examined soil organic carbon (SOC), total nitrogen (TN) and aboveground phytomass carbon(PhC) stocks in two areas of the Taymyr Peninsula, northern Siberia.We combined field sampling, chemical and14C radiocarbon dating analyses with land cover classifications for landscape-level assessments. The estimatedmean for the 0–100-cm depth SOC stocks was 14.8 and 20.8 kgCm−2 in Ary-Mas and Logata, respectively. Thecorresponding values for TN were 1.0 and 1.3 kgNm−2. On average, about 2% only (range 0–12%) of the totalecosystem C is stored in PhC. In both study areas about 34% of the SOC at 0–100 cm is stored in cryoturbatedpockets, which have formed since at least the early Holocene. The larger carbon/nitrogen (C/N) ratio of thiscryoturbated material indicates that it consists of relatively undecomposed soil organic matter (SOM). Thereare substantial differences in SOC stocks and SOM properties within and between the two study areas, whichemphasizes the need to consider both geomorphology and soil texture in the assessment of landscape-level andregional SOC stocks.

Highlights

• This research addresses landscape-scale and regional variation in SOC stocks.

• Landform and soil texture are taken into account in the analysis.

• The contribution of phytomass to total ecosystem C stored is limited.

• Large SOC stocks are susceptible to decomposition following permafrost thaw.

Keyword
soil organic carbon, total nitrogen, phytomass carbon, permafrost, cryoturbation, C/N ratios, radiocarbon dating, landscape inventories
National Category
Earth and Related Environmental Sciences
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-115705 (URN)10.1111/ejss.12357 (DOI)000384745900012 ()
Projects
The ESF CryoCARB projectthe Nordforsk NCoE DEFROST projectthe EU FP7 PAGE21 project
Funder
European Science Foundation (ESF)EU, FP7, Seventh Framework Programme
Available from: 2015-03-27 Created: 2015-03-27 Last updated: 2017-12-04Bibliographically approved
2. Storage, Landscape Distribution, and Burial History of Soil Organic Matter in Contrasting Areas of Continuous Permafrost
Open this publication in new window or tab >>Storage, Landscape Distribution, and Burial History of Soil Organic Matter in Contrasting Areas of Continuous Permafrost
Show others...
2015 (English)In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 47, no 1, p. 71-88Article in journal (Refereed) Published
Abstract [en]

This study describes and compares soil organic matter (SOM) quantity and characteristics in two areas of continuous permafrost, a mountainous region in NE Greenland (Zackenberg study site) and a lowland region in NE Siberia (Cherskiy and Shalaurovo study sites). Our assessments are based on stratified-random landscape-level inventories of soil profiles down to 1 m depth, with physico-chemical, elemental, and radiocarbon-dating analyses. The estimated mean soil organic carbon (SOC) storage in the upper meter of soils in the NE Greenland site is 8.3 ± 1.8 kg C m-2 compared to 20.3 ± 2.2 kg C m-2 and 30.0 ± 2.0 kg C m-2 in the NE Siberian sites (95% confidence intervals). The lower SOC storage in the High Arctic site in NE Greenland can be largely explained by the fact that 59% of the study area is located at higher elevation with mostly barren ground and thus very low SOC contents. In addition, SOC-rich fens and bogs occupy a much smaller proportion of the landscape in NE Greenland (∼3%) than in NE Siberia (∼20%). The contribution of deeper buried C-enriched material in the mineral soil horizons to the total SOC storage is lower in the NE Greenland site (∼13%) compared to the NE Siberian sites (∼24%–30%). Buried SOM seems generally more decomposed in NE Greenland than in NE Siberia, which we relate to different burial mechanisms prevailing in these regions.

Keyword
soil organic carbon, degree of decomposition in soil organic matter, radiocarbon dating, C/N ratios, continuous permafrost, slope processes, cryoturbation
National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-115639 (URN)10.1657/AAAR0014-027 (DOI)000350219000007 ()
Available from: 2015-03-27 Created: 2015-03-27 Last updated: 2018-01-11Bibliographically approved
3. Improved landscape partitioning and estimates of deep storage of soil organic carbon in the Zackenberg area (NE Greenland) using geomorphological landforms
Open this publication in new window or tab >>Improved landscape partitioning and estimates of deep storage of soil organic carbon in the Zackenberg area (NE Greenland) using geomorphological landforms
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This study aims to improve the previous soil organic carbon (SOC) storage estimates for the Zackenberg area (NE Greenland) that were based on a land cover classification (LCC) approach, by using geomorphological upscaling. In addition, novel SOC estimates for deeper deposits (to 300 cm depth) are presented. We hypothesize that landforms will better represent the long-term slope and depositional processes that result in deep SOC burial in this type of mountain permafrost environments. The updated mean SOC storage for the 0–100 cm soil depth is 4.8 kg C m−2, which is 42% lower than the previous estimate of 8.3 kg C m−2 based on land cover upscaling. We ascribe the difference to a previous areal overestimate of SOC-rich vegetated land cover classes. The landform-based approach more correctly constrains the depositional areas in alluvial fans and deltas with high SOC storage. These are also areas of deep carbon storage with an additional 2.4 kg C m−2 in the 100–300 cm depth interval. This research emphasizes the need to consider geomorphology when assessing SOC pools in mountain permafrost landscapes.

National Category
Climate Research
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-137312 (URN)
Available from: 2017-01-03 Created: 2017-01-03 Last updated: 2017-01-09Bibliographically approved
4. Grain size controls on cryoturbation and soil organic carbon density in permafrost-affected soils
Open this publication in new window or tab >>Grain size controls on cryoturbation and soil organic carbon density in permafrost-affected soils
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This meta-analysis aims to describe the relationship between grain size distributions and soil organic carbon (SOC) storage in mineral subsoil and carbon (C)-enriched cryoturbated pockets in five areas of continuous permafrost that differ in glaciation history and soil parent materials. Our results show a positive relationship between fine-grained (colloid to medium silt) fractions and SOC storage. Finer textured soils had a significantly higher SOC storage in mineral subsoil samples (not C-enriched through cryoturbation) than coarser textured soils. However, the process of C-enrichment through cryoturbation was most pronounced in soils with coarser grain sizes in the range of coarse silt and very fine sand. Even though fine-grained textures provide a better physical and biochemical protection for soil organic matter, their strong cohesion reduces the mixing of soil horizons and the effectiveness of cryoturbation. A higher % coarse silt to % clay ratio in samples was a good predictor of C-enrichment through cryoturbation across soil samples, soil profiles and study areas.

Keyword
permafrost soils, SOC storage, cryoturbation, soil parent materials, soil texture, grain size distributions
National Category
Earth and Related Environmental Sciences
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-137284 (URN)
Available from: 2017-01-02 Created: 2017-01-02 Last updated: 2017-01-05Bibliographically approved

Open Access in DiVA

fulltext(9222 kB)85 downloads
File information
File name FULLTEXT01.pdfFile size 9222 kBChecksum SHA-512
7338df1935a1945d80febefc20a75bf5a59efc2749bc011f237fba5bdcf1197e6829d6776d9084207e67a6392e13390861105c1bfed2f4a5c15b7b50eed8917e
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Palmtag, Juri
By organisation
Department of Physical Geography
Physical GeographyClimate Research

Search outside of DiVA

GoogleGoogle Scholar
Total: 85 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 3168 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf