Vulnerability of carbon in Cryosols – substrate-microorganisms-aggregate interactions

• Applicants: Professor Dr. Georg Guggenberger; Professor Dr. Tim Urich; Dr. Cordula Vogel
• Subject Area: Soil Sciences
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 431968700

• Final Report Year: 2025

Final Report Abstract

The bilateral project CryoVulcan dealt with the consequences of thawing permafrost and its effects on the stability and microbial turnover of soil organic matter (SOM) under different soil hydrological conditions. Year-round monitoring of the redox potential in the soil was accompanied by physico-chemical analyses, stable isotope studies and microbiological analyses at DNA, RNA and metatranscriptome level. Organic carbon (OC) stocks were 60-75% lower in soil profiles of degraded sites, regardless of whether soils were wet or well-drained. Processes such as anaerobic inhibition of microbial decomposition or formation of highly reactive pedogenic mineral phases and pronounced aggregation appeared to stabilize only a small proportion of the organic matter formerly stored in the permafrost in the long term. Losses of OC were mainly detected in the subsoils, while topsoils apparently showed no significant losses due to increased input of plant litter. Hydromorphic subsoils were less anaerobic than assumed, and showed like their well-drained counterparts quite high root density in the subsoil. Laboratory experiments demonstrated an accelerated decomposition of complex organic compounds by root exudates, which are assumed to be released in higher quantities in the degraded soils regardless of their hydrological regime. In-situ incubation experiments with 13C-labeled litter in the soil further indicated a high translocation of organic substances. The results of the Cryo- Vulcan project show that in degrading permafrost soils the effect of alternative stabilization mechanisms is limited and SOM is mobilized, mainly via mineralization, but partly also via translocation in dissolved form. Further research should shed more light on translocation and transformation of SOM in whole degrading permafrost soil landscapes, especially at the interface with the hydrosphere.

Publications

• Fungi in Permafrost-Affected Soils of the Canadian Arctic: Horizon- and Site-Specific Keystone Taxa Revealed by Co-Occurrence Network. Microorganisms, 9(9), 1943.
  Varsadiya, Milan; Urich, Tim; Hugelius, Gustaf & Bárta, Jiří
  
• Microbiome structure and functional potential in permafrost soils of the Western Canadian Arctic. FEMS Microbiology Ecology, 97(3).
  Varsadiya, Milan; Urich, Tim; Hugelius, Gustaf & Bárta, Jiří
  
• Buried but not dead: Microbiomes of Arctic Cryosols. Oral presentation at the Ecology of Soil Microorganisms Conference 2022, Prague, Czech Republic.
  Bárta, J.
  
• Extracellular enzyme ratios reveal locality and horizon-specific carbon, nitrogen, and phosphorus limitations in Arctic permafrost soils. Biogeochemistry, 161(2), 101-117.
  Varsadiya, Milan; Liebmann, Patrick; Petters, Sebastian; Hugelius, Gustaf; Urich, Tim; Guggenberger, Georg & Bárta, Jiří
  
• Extracellular enzyme ratios reveal locality and horizon-specific carbon, nitrogen, and phosphorus limitations in Arctic permafrost soils. Poster contribution, Ecology of Soil Microorganisms Conference 2022, Prague, Czech Republic.
  Varsadiya, M., Liebmann, P., Petters, S., Hugelius, G., Urich, T., Guggenberger, G. & Bárta, J.
  
• Isolation and identification of EPS producing bacteria from the permafrost degraded soil of Fairbanks, Alaska. Poster contribution, Ecology of Soil Microorganisms Conf. 2022, Prague, Czech Republic.
  Waqas, M. & Bárta, J.
  
• Microbiome assembly in thawing permafrost and its feedbacks to climate. Global Change Biology, 28(17), 5007-5026.
  Ernakovich, Jessica G.; Barbato, Robyn A.; Rich, Virginia I.; Schädel, Christina; Hewitt, Rebecca E.; Doherty, Stacey J.; Whalen, Emily D.; Abbott, Benjamin W.; Barta, Jiri; Biasi, Christina; Chabot, Chris L.; Hultman, Jenni; Knoblauch, Christian; Vetter, Maggie C. Y. Lau; Leewis, Mary‐Cathrine; Liebner, Susanne; Mackelprang, Rachel; Onstott, Tullis C.; Richter, Andreas ... & Winkel, Matthias
  
• Changes in SOC storage under wet and dry conditions following permafrost thaw in Interior Alaska. Poster contribution to the German Soil Science Society Conference 2023, Halle (Salle), Germany.
  Liebmann, P., Vogel, C., Bárta, J., Urich, T., Mewes, O., Kholodov, A. & Guggenberger, G.
  
• Density fractionation reworked: Reduce material and costs. Journal of Plant Nutrition and Soil Science, 186(4), 383-386.
  Liebmann, Patrick; Mewes, Ole & Guggenberger, Georg
  
• Extracellular polymeric substances in soil – Possible functions and ways to study. Oral presentation at the MicroSoil 2023, Feedback between Soil Microstructures/the Microhabitat and Soil Biota, Deux Sévres, France
  Vogel, C.
  
• Census of below-ground biota associated with permafrost affected soils of western Greenland, with a focus on trophic structure. European Journal of Soil Biology, 121, 103623.
  Petters, Sebastian; Varsadiya, Milan; Liebmann, Patrick; Schnecker, Jörg; Guggenberger, Georg; Bárta, Jiří & Urich, Tim
  
• Different hydrological conditions after permafrost thaw result in distinct microbial community compositions. openRxiv.
  Waqas, Muhammad; Liebmann, Patrick; Vogel, Cordula; Varsadiya, Milan; Wang, Haitao; Shibistova, Olga; Novák, Milan; Urich, Tim; Guggenberger, Georg & Bárta, Jiří
  
• Extracellular polymeric substances in soil - Possibilities to improve our understanding. Oral Presentation at INRA, Paris, France
  Vogel, C.
  
• Permafrost degradation and its consequences for carbon storage in soils of Interior Alaska. Biogeochemistry, 167(3), 199-223.
  Liebmann, Patrick; Bárta, Jiří; Vogel, Cordula; Urich, Tim; Kholodov, Alexander; Varsadiya, Milan; Mewes, Ole; Dultz, Stefan; Waqas, Muhammad; Wang, Haitao; Shibistova, Olga & Guggenberger, Georg
  
• Stick together: Isolation and characterization of exopolysaccharide producing bacteria from degraded permafrost soils. openRxiv.
  Waqas, Muhammad; Zelenková, Simona; Vogel, Cordula; Rühmann, Broder; Varsadiya, Milan; Liebmann, Patrick; Wang, Haitao; Shibistova, Olga; Urich, Tim; Guggenberger, Georg & Bárta, Jiří
  
• The methane-cycling microbiome in intact and degraded permafrost soils of the pan-Arctic. openRxiv.
  Wang, Haitao; Lindemann, Erik; Liebmann, Patrick; Varsadiya, Milan; Svenning, Mette Marianne; Waqas, Muhammad; Petters, Sebastian; Richter, Andreas; Guggenberger, Georg; Barta, Jiri & Urich, Tim
  
• Long-term soil redox dynamics of intact and degraded permafrost in Interior Alaska. Copernicus GmbH.
  Liebmann, Patrick; Vogel, Cordula; Barta, Jiri; Urich, Tim; Kholodov, Alexander; Varsadiya, Milan; Waqas, Muhammad; Wang, Haitao; Donnerhack, Oliver; Shibistova, Olga; Wessel-Bothe, Stefan; Mansfeldt, Tim & Guggenberger, Georg