Marcus Schiedung

Last Name

Schiedung

First Name

Marcus

ORCID

0000-0002-0185-9867

Organisational unit

01709 - Lehre Umweltsystemwissenschaften

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Publications 1 - 5 of 5

Millennial-aged pyrogenic carbon in high-latitude mineral soils
Schiedung, Marcus; Ascough, Philippa; Bellè, Severin-Luca; et al. (2024)
Communications Earth & Environment
Wildfires in the Arctic are producing pyrogenic carbon as product of incomplete biomass combustion. The storage and distribution of pyrogenic carbon in soils is poorly known, especially in carbon rich permafrost-affected mineral soils. Here, we extracted pyrogenic carbon in mineral soils from eleven forest sites across the North Canadian permafrost regions by hydrogen pyrolysis. We found pyrogenic carbon with millennial-scale ages that were older in continuous (1960–12,690 calibrated years before present) than in discontinuous (510–3560 calibrated years before present) permafrost-affected soils. In all cases, pyrogenic carbon showed longer residence times compared to bulk soil organic carbon. The proportions of pyrogenic carbon on total soil organic carbon were consistent at 6.9 ± 0.5% of total soil organic carbon. Thus, pyrogenic carbon forms a significant component of the total soil organic carbon and climatic as well as soil factors control the long residence times of pyrogenic carbon in vulnerable high-latitude forest mineral soils.
Soil carbon losses due to priming moderated by adaptation and legacy effects
Schiedung, Marcus; Don, Axel; Beare, Michael H.; et al. (2023)
Nature Geoscience
Increasing soil organic carbon contents contributes to global climate change mitigation. However, new plant inputs can enhance the mineralization of native soil organic carbon by the positive priming effect, which may counterbalance the sequestration of new carbon. Here we use soils from a 20 year chronosequence of inverted pasture soils (reciprocal translocation of topsoil and subsoil to >1 m) to study the dynamics of soil organic carbon in topsoils and subsoils. We evaluated the root-induced priming effect by differentiating native soil organic carbon from 13C root-derived carbon in a 6 month incubation experiment. We found that the addition of fresh root-derived carbon caused positive priming of native soil organic carbon in new topsoils (109 ± 27% additional respiration compared with controls without roots) and subsoils (331 ± 84%) after inversion. This effect was temporary for new topsoils as they accumulated soil organic carbon and adapted to high carbon inputs within a few years, leading to no priming in the long term. In contrast, buried topsoils became more sensitive to root carbon inputs over time, demonstrating how the legacy of high carbon inputs mediates the magnitude of priming (50% to 390% after 20 years of inversion). Overall, carbon losses with priming never exceeded new root-derived carbon inputs. We conclude that priming is a temporary reaction to additional carbon, which attenuates when soils adapt to high carbon inputs within a few years to decades.
Root litter quality drives the dynamic of native mineral-associated organic carbon in a temperate agricultural soil
Poeplau, Christopher; Begill, Neha; Liang, Zhi; et al. (2023)
Plant and Soil
Background and aims Understanding the fate and residence time of organic matter added to soils, and its effect on native soil organic carbon (SOC) mineralisation is key for developing efficient SOC sequestration strategies. Here, the effect of litter quality, particularly the carbon-to-nitrogen (C:N) ratio, on the dynamics of particulate (POC) and mineral-associated organic carbon (MAOC) were studied. Methods In a two-year incubation experiment, root litter samples of the C4-grass Miscanthus with four different C:N ratios ranging from 50 to 124 were added to a loamy agricultural topsoil. In an additional treatment, ammonium nitrate was added to the C:N 124 litter to match the C:N 50 litter input ratio. Soils were size-fractionated after 6, 12 and 24 months and δ13C was measured to determine the proportion of new and native POC and MAOC. Litter quality was further assessed by mid-infrared spectroscopy and compound peak analysis. Results Litter quality strongly affected SOC dynamics, with total SOC losses of 42.5 ± 3.0% in the C:N 50 treatment and 48.9 ± 3.0% in the C:N 124 treatment after 24 months. Largest treatment effects occurred in mineralisation of native MAOC, which was strongly primed by litter addition. The N amendment in the C:N 124 treatment did not alleviate this potential N mining flux. Conclusion Litter quality plays a major role in overall SOC dynamics, and priming for N mining from the MAOC pool could be a dominant mechanism. However, adding N did not compensate for poor litter quality, highlighting the role of litter quality beyond stoichiometric imbalances.
Belowground plant allocation regulates rice methane emissions from degraded peat soils
Sriskandarajah, Nijanthini; Wüst-Galley, Chloé; Heller, Sandra; et al. (2024)
Scientific Reports
Carbon-rich peat soils have been drained and used extensively for agriculture throughout human history, leading to significant losses of their soil carbon. One solution for rewetting degraded peat is wet crop cultivation. Crops such as rice, which can grow in water-saturated conditions, could enable agricultural production to be maintained whilst reducing CO2 and N2O emissions from peat. However, wet rice cultivation can release considerable methane (CH4). Water table and soil management strategies may enhance rice yield and minimize CH4 emissions, but they also influence plant biomass allocation strategies. It remains unclear how water and soil management influences rice allocation strategies and how changing plant allocation and associated traits, particularly belowground, influence CH4-related processes. We examined belowground biomass (BGB), aboveground biomass (AGB), belowground:aboveground ratio (BGB:ABG), and a range of root traits (root length, root diameter, root volume, root area, and specific root length) under different soil and water treatments; and evaluated plant trait linkages to CH4. Rice (Oryza sativa L.) was grown for six months in field mesocosms under high (saturated) or low water table treatments, and in either degraded peat soil or degraded peat covered with mineral soil. We found that BGB and BGB:AGB were lowest in water saturated conditions where mineral soil had been added to the peat, and highest in low-water table peat soils. Furthermore, CH4 and BGB were positively related, with BGB explaining 60% of the variation in CH4 but only under low water table conditions. Our results suggest that a mix of low water table and mineral soil addition could minimize belowground plant allocation in rice, which could further lower CH4 likely because root-derived carbon is a key substrate for methanogenesis. Minimizing root allocation, in conjunction with water and soil management, could be explored as a strategy for lowering CH4 emissions from wet rice cultivation in degraded peatlands.
Biomarker 14C evidence for sources and recycling of pre-aged organic carbon in Arctic permafrost regions
Lattaud, Julie; Eglinton, Timothy Ian; Haghipour, Negar; et al. (2025)
Geochimica et Cosmochimica Acta
Permafrost thaw has the potential to release ancient particulate and dissolved organic matter that had been stored for thousands of years. Previous studies have shown that dissolved organic matter from permafrost is very labile and can be used by heterotrophic microbes close to the thaw area. However, it is unknown if ancient particulate organic matter can also be utilized. This study aims to investigate whether arctic microbial communities (bacteria and Archaea) incorporate ancient organic matter potentially released from thawing permafrost into their biomass. We compare and contrast the radiocarbon signatures of microbial lipids and higher plant biomarkers (representing terrestrial organic matter) from five soil profiles and seven deltaic lake sediment cores from the Mackenzie River drainage basin, Arctic Canada. In the surface soils, modern to post-modern short-chain fatty acids (SCFA) ages indicate in situ microbial production, with differential rates of organic carbon (OC) cycling depending on soil moisture. In contrast, SCFA in deeper soils display millennial ages, which likely represent the microbial necromass preserved through mineral association. In deltaic lakes that are disconnected from the river, generally old SCFA suggests the uptake of pre-aged OC by bacteria. In perennially connected lakes, pre-aged SCFA could originate from in situ microbial uptake of old OC or from the Mackenzie River. Higher plant-derived long-chain fatty acids (LCFA) present older radiocarbon ages, reflecting mineral stabilization during either pre-aging in soils (for high closure lakes) or riverine transport (for no and low closure lakes). Archaeal lipids are younger than SCFA and LCFA in high closure lakes, and older in low and no closure lakes, mirroring bulk radiocarbon signatures due to their heterotrophic production. These radiocarbon signatures of bacterial biomarker lipids may therefore reflect microbial incorporation of ancient OC (e.g., derived from permafrost thaw) or exceptional preservation (e.g., through mineral stabilization). Hence, even in relatively high OC environments such as arctic aquatic ecosystems, microbes can rely on ancient OC for their growth.

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Marcus Schiedung

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