TY - JOUR

T1 - Fate of carbohydrates and lignin in north-east Siberian permafrost soils

AU - Dao, Thao Thi

AU - Gentsch, Norman

AU - Mikutta, Robert

AU - Sauheitl, Leopold

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 Minister of Education and Research ( 03F0616A ) within the ERANET EUROPOLAR project CryoCARB. T.T. Dao is grateful for financial support by the Project 911 of Vietnamese Education . O. Shibistova and G. Guggenberger appreciate funding from the Russian Ministry of Education and Science (?. 14.B25.31.0031 ), and A. Richter acknowledges the financial support of the Austrian Science Fund (FWF – I370-B17 ). Further co-funding came from RFBR and Government of Krasnoyarsk Territory (? 16-44-242145 ). We are grateful to the technical staff of the Institute of Soil Science in Hannover for laboratory assistance and to Susanne K. Woche for comments on the manuscript.

PY - 2018/1

Y1 - 2018/1

N2 - Permafrost soils preserve huge amounts of organic carbon (OC) prone to decomposition under changing climatic conditions. However, knowledge on the composition of soil organic matter (OM) and its transformation and vulnerability to decomposition in these soils is scarce. We determined neutral sugars and lignin-derived phenols, released by trifluoroacetic acid (TFA) and CuO oxidation, respectively, within plants and soil density fractions from the active layer and the upper permafrost layer at three different tundra types (shrubby grass, shrubby tussock, shrubby lichen) in the Northeast Siberian Arctic. The heavy fraction (HF; >1.6 g mL−1) was characterized by a larger enrichment of microbial sugars (hexoses vs. pentoses) and more pronounced lignin degradation (acids vs. aldehydes) as compared to the light fraction (LF; <1.6 g mL−1), showing the transformation from plant residue-dominated particulate OM to a largely microbial imprint in mineral-associated OM. In contrast to temperate and tropical soils, total neutral sugar contents and galactose plus mannose to arabinose plus xylose ratios (GM/AX) decreased in the HF with soil depth, which may indicate a process of effective recycling of microbial biomass rather than utilizing old plant materials. At the same time, lignin-derived phenols increased and the degree of oxidative decomposition of lignin decreased with soil depth, suggesting a selective preservation of lignin presumably due to anaerobiosis. As large parts of the plant-derived pentoses are incorporated in lignocelluloses and thereby protected against rapid decomposition, this might also explain the relative enrichment of pentoses with soil depth. Hence, our results show a relatively large contribution of plant-derived OM, particularly in the buried topsoil and subsoil, which is stabilized by the current soil environmental conditions but may become available to decomposers if permafrost degradation promotes soil drainage and improves the soil oxygen supply.

AB - Permafrost soils preserve huge amounts of organic carbon (OC) prone to decomposition under changing climatic conditions. However, knowledge on the composition of soil organic matter (OM) and its transformation and vulnerability to decomposition in these soils is scarce. We determined neutral sugars and lignin-derived phenols, released by trifluoroacetic acid (TFA) and CuO oxidation, respectively, within plants and soil density fractions from the active layer and the upper permafrost layer at three different tundra types (shrubby grass, shrubby tussock, shrubby lichen) in the Northeast Siberian Arctic. The heavy fraction (HF; >1.6 g mL−1) was characterized by a larger enrichment of microbial sugars (hexoses vs. pentoses) and more pronounced lignin degradation (acids vs. aldehydes) as compared to the light fraction (LF; <1.6 g mL−1), showing the transformation from plant residue-dominated particulate OM to a largely microbial imprint in mineral-associated OM. In contrast to temperate and tropical soils, total neutral sugar contents and galactose plus mannose to arabinose plus xylose ratios (GM/AX) decreased in the HF with soil depth, which may indicate a process of effective recycling of microbial biomass rather than utilizing old plant materials. At the same time, lignin-derived phenols increased and the degree of oxidative decomposition of lignin decreased with soil depth, suggesting a selective preservation of lignin presumably due to anaerobiosis. As large parts of the plant-derived pentoses are incorporated in lignocelluloses and thereby protected against rapid decomposition, this might also explain the relative enrichment of pentoses with soil depth. Hence, our results show a relatively large contribution of plant-derived OM, particularly in the buried topsoil and subsoil, which is stabilized by the current soil environmental conditions but may become available to decomposers if permafrost degradation promotes soil drainage and improves the soil oxygen supply.

KW - Carbohydrates

KW - Lignin

KW - Permafrost

KW - Soil biomarker

KW - Soil fraction

UR - http://www.scopus.com/inward/record.url?scp=85032792657&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2017.10.032

DO - 10.1016/j.soilbio.2017.10.032

M3 - Article

AN - SCOPUS:85032792657

VL - 116

SP - 311

EP - 322

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

ER -