Evidence for preferential protein depolymerization in wetland soils  in response to external nitrogen availability provided by a novel FTIR routine

Reuter, Hendrik; Gensel, Julia; Elvert, Marcus; Zak, Dominik

doi:10.5194/bg-17-499-2020

Cited by 13 publications

(10 citation statements)

References 59 publications

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“…C/N ratios in cores CEN-17.4, EKGKM7-2019 and EKG03 are also related to decomposition processes. The response of C/N ratios to decomposition depends, in part, on peat nutrient status with low-nutrient peats being characterized by preferential protein loss 56 . The observed topmost increase in the C/N ratios with depth (Fig.…”

Section: Methodsmentioning

confidence: 99%

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

Garcin

Schefuß

Dargie

et al. 2022

Nature

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The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr bp; taken as ad 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr bp is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr bp and culminating at approximately 2,000 cal. yr bp, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr bp, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation–loss–accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system.

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Section: Methodsmentioning

confidence: 99%

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

Garcin

Schefuß

Dargie

et al. 2022

Nature

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“…The proposed progressive cycles of microbial processing, including exoenzyme activity, and release of cellular compounds associated to water stress over desiccation, would explain such a trend of increasing C:N ratio for HMWS. Together, the increased C:N ratio and the decline of HMWS strongly suggest preferential protein depolymerization (Reuter et al 2020).…”

Section: Gaseous C Fluxes In Response To Rainfallmentioning

confidence: 98%

Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream

et al. 2021

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Droughts are recognized to impact global biogeochemical cycles. However, the implication of desiccation on in-stream carbon (C) cycling is not well understood yet. We subjected sediments from a lowland, organic rich intermittent stream to experimental desiccation over a 9-week-period to investigate temporal changes in microbial functional traits in relation to their redox requirements, carbon dioxide (CO2) and methane (CH4) fluxes and water-soluble organic carbon (WSOC). Concurrently, the implications of rewetting by simulated short rainfalls (4 and 21 mm) on gaseous C fluxes were tested. Early desiccation triggered dynamic fluxes of CO2 and CH4 with peak values of 383 and 30 mg C m−2 h−1 (mean ± SD), respectively, likely in response to enhanced aerobic mineralization and accelerated evasion. At longer desiccation, CH4 dropped abruptly, likely because of reduced abundance of anaerobic microbial traits. The CO2 fluxes ceased later, suggesting aerobic activity was constrained only by extended desiccation over time. We found that rainfall boosted fluxes of CO2, which were modulated by rainfall size and the preceding desiccation time. Desiccation also reduced the amount of WSOC and the proportion of labile compounds leaching from sediment. It remains questionable to which extent changes of the sediment C pool are influenced by respiration processes, microbial C uptake and cell lysis due to drying-rewetting cycles. We highlight that the severity of the dry period, which is controlled by its duration and the presence of precipitation events, needs detailed consideration to estimate the impact of intermittent flow on global riverine C fluxes.

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“…Substrate availability limits protein depolymerization in subsoil and plant litter (Mooshammer et al 2012 ; Ma et al 2020 ), and explained 60–70% of variation in gross protein depolymerization across several land uses (Noll et al 2019b ). Depolymerization is one strategy by which microbes may acquire N in response to N limitation or C excess: nutrient scarcity induces microbes to preferentially decompose N-bearing polymers from leaf litter (Reuter et al 2020 ), and labile C additions increased gross depolymerization rates (Noll et al 2019b ). Alternately, depolymerization could be a C acquisition strategy: in some studies, excess C lowered amino acid and peptide uptake (Farrell et al 2014 ; Yang et al 2020 ) and increasing litter C:N was associated with lower rates of gross depolymerization (Mooshammer et al 2012 ).…”

Section: Model Detailsmentioning

confidence: 99%

A holistic framework integrating plant-microbe-mineral regulation of soil bioavailable nitrogen

et al. 2021

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Soil organic nitrogen (N) is a critical resource for plants and microbes, but the processes that govern its cycle are not well-described. To promote a holistic understanding of soil N dynamics, we need an integrated model that links soil organic matter (SOM) cycling to bioavailable N in both unmanaged and managed landscapes, including agroecosystems. We present a framework that unifies recent conceptual advances in our understanding of three critical steps in bioavailable N cycling: organic N (ON) depolymerization and solubilization; bioavailable N sorption and desorption on mineral surfaces; and microbial ON turnover including assimilation, mineralization, and the recycling of microbial products. Consideration of the balance between these processes provides insight into the sources, sinks, and flux rates of bioavailable N. By accounting for interactions among the biological, physical, and chemical controls over ON and its availability to plants and microbes, our conceptual model unifies complex mechanisms of ON transformation in a concrete conceptual framework that is amenable to experimental testing and translates into ideas for new management practices. This framework will allow researchers and practitioners to use common measurements of particulate organic matter (POM) and mineral-associated organic matter (MAOM) to design strategic organic N-cycle interventions that optimize ecosystem productivity and minimize environmental N loss.

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Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine

Cited by 13 publications

References 59 publications

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

Hydroclimatic vulnerability of peat carbon in the central Congo Basin

Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream

A holistic framework integrating plant-microbe-mineral regulation of soil bioavailable nitrogen

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