TY - JOUR

T1 - Lignin Preservation and Microbial Carbohydrate Metabolism in Permafrost Soils

AU - Dao, Thao Thi

AU - Mikutta, Robert

AU - Sauheitl, Leopold

AU - Gentsch, Norman

AU - Shibistova, Olga

AU - Wild, Birgit

AU - Schnecker, Jörg

AU - Bárta, Jiří

AU - Čapek, Petr

AU - Gittel, Antje

AU - Lashchinskiy, Nikolay

AU - Urich, Tim

AU - Šantrůčková, Hana

AU - Richter, Andreas

AU - Guggenberger, Georg

N1 - Funding Information: Financial support was provided by the German Federal Ministry of Education and Research (03F0616A) within the ERANET EUROPOLAR project CryoCARB. T.T. Dao is grateful for financial support from Vietnamese Education, O. Shibistova acknowledges funding from the National Science Foundation of China and Russian Foundation for Basic Research (NSFC‐RFBR joint project No 19‐54‐53026), and A. Richter, B. Wild and J. Schnecker appreciate the financial support from the Austrian Science Fund (FWF ‐ I370‐B17). We thank all members of the CryoCARB project team for their incredible team spirit. We are grateful to the technical staff of the Institute of Soil Science in Hannover for great laboratory assistance. Open access funding enabled and organized by Projekt DEAL.

PY - 2022/1

Y1 - 2022/1

N2 - Permafrost-affected soils in the northern circumpolar region store more than 1,000 Pg soil organic carbon (OC), and are strongly vulnerable to climatic warming. However, the extent to which changing soil environmental conditions with permafrost thaw affects different compounds of soil organic matter (OM) is poorly understood. Here, we assessed the fate of lignin and non-cellulosic carbohydrates in density fractionated soils (light fraction, LF vs. heavy fraction, HF) from three permafrost regions with decreasing continentality, expanding from east to west of northern Siberia (Cherskiy, Logata, Tazovskiy, respectively). In soils at the Tazovskiy site with thicker active layers, the LF showed smaller OC-normalized contents of lignin-derived phenols and plant-derived sugars and a decrease of these compounds with soil depth, while a constant or even increasing trend was observed in soils with shallower active layers (Cherskiy and Logata). Also in the HF, soils at the Tazovskiy site had smaller contents of OC-normalized lignin-derived phenols and plant-derived sugars along with more pronounced indicators of oxidative lignin decomposition and production of microbial-derived sugars. Active layer deepening, thus, likely favors the decomposition of lignin and plant-derived sugars, that is, lignocelluloses, by increasing water drainage and aeration. Our study suggests that climate-induced degradation of permafrost soils may promote carbon losses from lignin and associated polysaccharides by abolishing context-specific preservation mechanisms. However, relations of OC-based lignin-derived phenols and sugars in the HF with mineralogical properties suggest that future OM transformation and carbon losses will be modulated in addition by reactive soil minerals.

AB - Permafrost-affected soils in the northern circumpolar region store more than 1,000 Pg soil organic carbon (OC), and are strongly vulnerable to climatic warming. However, the extent to which changing soil environmental conditions with permafrost thaw affects different compounds of soil organic matter (OM) is poorly understood. Here, we assessed the fate of lignin and non-cellulosic carbohydrates in density fractionated soils (light fraction, LF vs. heavy fraction, HF) from three permafrost regions with decreasing continentality, expanding from east to west of northern Siberia (Cherskiy, Logata, Tazovskiy, respectively). In soils at the Tazovskiy site with thicker active layers, the LF showed smaller OC-normalized contents of lignin-derived phenols and plant-derived sugars and a decrease of these compounds with soil depth, while a constant or even increasing trend was observed in soils with shallower active layers (Cherskiy and Logata). Also in the HF, soils at the Tazovskiy site had smaller contents of OC-normalized lignin-derived phenols and plant-derived sugars along with more pronounced indicators of oxidative lignin decomposition and production of microbial-derived sugars. Active layer deepening, thus, likely favors the decomposition of lignin and plant-derived sugars, that is, lignocelluloses, by increasing water drainage and aeration. Our study suggests that climate-induced degradation of permafrost soils may promote carbon losses from lignin and associated polysaccharides by abolishing context-specific preservation mechanisms. However, relations of OC-based lignin-derived phenols and sugars in the HF with mineralogical properties suggest that future OM transformation and carbon losses will be modulated in addition by reactive soil minerals.

KW - carbohydrate

KW - density fractionation

KW - lignin

KW - mineral-associated organic matter

KW - permafrost soils

KW - soil organic matter decomposition

UR - http://www.scopus.com/inward/record.url?scp=85123702620&partnerID=8YFLogxK

U2 - 10.1029/2020JG006181

DO - 10.1029/2020JG006181

M3 - Article

AN - SCOPUS:85123702620

VL - 127

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 2169-8953

IS - 1

M1 - e2020JG006181

ER -