Effects of soil macro- and mesofauna on litter decomposition and soil organic matter stabilization

Geoderma ◽  
2018 ◽  
Vol 332 ◽  
pp. 161-172 ◽  
Author(s):  
Jan Frouz
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Decomposition ◽  
Organic Matter Stabilization

Soil texture affects the coupling of litter decomposition and soil organic matter formation

2021 ◽  
pp. 108302
Author(s):  
Gerrit Angst ◽  
Jan Pokorný ◽  
Carsten W. Mueller ◽  
Isabel Prater ◽  
Sebastian Preusser ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Decomposition ◽  
Soil Texture ◽  
Soil Organic Matter Formation

The long-term impact of low-intensity surface fires on litter decomposition and enzyme activities in boreal coniferous forests

2016 ◽  
Vol 25 (2) ◽  
pp. 213 ◽  
Author(s):  
Kajar Köster ◽  
Frank Berninger ◽  
Jussi Heinonsalo ◽  
Aki Lindén ◽  
Egle Köster ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Enzymatic Activity ◽  
Litter Decomposition ◽  
Forest Fires ◽  
Biological Activities ◽  
Coniferous Forest ◽  
Fire Disturbance ◽  
Coniferous Forests ◽  
Long Term Impact

In boreal forest ecosystems fire, fungi and bacteria, and their interactions, have a pronounced effect on soil carbon dynamics. In this study we measured enzymatic activities, litter decomposition rates, carbon stocks and fungal and microbial biomasses in a boreal subarctic coniferous forest on a four age classes of non-stand replacing fire chronosequence (2, 42, 60 and 152 years after the fire). The results show that microbial activity recovered slowly after fire and the decomposition of new litter was affected by the disturbance. The percent mass loss of Scots pine litter increased with time from the last fire. Slow litter decomposition during the first post-fire years accelerates soil organic matter accumulation that is essential for the recovery of soil biological activities. Fire reduced the enzymatic activity across all the enzyme types measured. Carbon-degrading, chitin-degrading and phosphorus-dissolving enzymes showed different responses with the time elapsed since the fire disturbance. Microbial and enzymatic activity took decades before recovering to the levels observed in old forest stands. Our study demonstrates that slower post-fire litter decomposition has a pronounced impact on the recovery of soil organic matter following forest fires in northern boreal coniferous forests.

scholarly journals Integrating plant litter quality, soil organic matter stabilization, and the carbon saturation concept

2015 ◽  
Vol 21 (9) ◽  
pp. 3200-3209 ◽  
Author(s):  
Michael J. Castellano ◽  
Kevin E. Mueller ◽  
Daniel C. Olk ◽  
John E. Sawyer ◽  
Johan Six
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Quality ◽  
Plant Litter ◽  
Carbon Saturation ◽  
Organic Matter Stabilization

A molecular dynamic study of Soil Organic Matter stabilization mechanisms

2021 ◽  
Author(s):  
Edgar Galicia-Andrés ◽  
Yerko Escalona ◽  
Peter Grančič ◽  
Chris Oostenbrink ◽  
Daniel Tunega ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Clay Mineralogy ◽  
Metal Cations ◽  
Dense Matter ◽  
Chemical Degradation ◽  
Molecular Graphics ◽  
Organic Matter Stabilization ◽  
Reactive Surfaces

<p>It is well known that some fractions of soil organic matter (SOM) can resist to physical and (bio)chemical degradation which can be attributed to factors ranging from molecular properties to the preference for digesting other molecular species by microorganisms. Some mechanisms, by which organic matter is protected, are often referred to as: physical stabilization through microaggregation, chemical stabilization by formation of SOM-mineral aggregates, and biochemical stabilization through the formation of recalcitrant SOM.</p><p>Protection mechanisms are responsible for the accumulation process of organic carbon, reducing the exposure of organic matter and making it less vulnerable to microbial, enzymatic or chemical attacks. In these mechanisms, water molecular bridges and metal cation bridges play a key role. Cation bridges serve as aggregation sites on humic substances, forming dense matter, in comparison to systems where bridges are missing. This effect is enhanced in systems with cations at higher oxidation states.</p><p>By using the modeler tool developed in our group (Vienna Soil–Organic–Matter Modeler, VSOMM2) (Escalona et al., 2021), we generated aggregate models of humic substances at atomistic scale reflecting the diversity in composition, size and conformations of the constituting molecules. Further, we built models of organo-clay aggregates using kaolinite and montmorillonite as typical soil minerals. This allowed a systematic study to understand the effect of the surrounding environment at microscopic scale, not fully accessible experimentally.</p><p>Molecular simulations of the adsorption process of SOM aggregates on the reactive surfaces of led to two observations: 1) the humic substances aggregates were able to interact with the reactive surfaces mainly via hydrogen bonds forming stable organic matter-clay complexes and 2) the aggregates subsequently lost rigidity and stability after metal cations removing, consequently leading to a gradual loss of humic substance molecules, evidencing the role of metal cations in the protection mechanism of soil organic matter aggregates and possibly explaining its recalcitrance (Galicia-Andrés et al., 2021).</p><p>References</p><ul><li>Escalona, Y., Petrov, D., & Oostenbrink, C. (2021). Vienna soil organic matter modeler 2 (VSOMM2). Journal of Molecular Graphics and Modelling, 103, 107817. https://doi.org/10.1016/j.jmgm.2020.107817</li> <li>Galicia-Andrés, E., Grančič, P., Gerzabek, M. H., Oostenbrink, C., & Tunega, D. (2021). Modeling of interactions in natural and synthetic organoclays. In I. C. Sainz Diaz (Ed.), Computational modeling in clay mineralogy.</li> </ul>

Soil organic matter in soils of the Russian Arctic: insights from 13C-NMR spectroscopy

2020 ◽  
Author(s):  
Ivan Alekseev ◽  
Evgeny Abakumov
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Humic Acids ◽  
13C Nmr ◽  
Cold Climate ◽  
Molecular Organization ◽  
Cold Temperatures ◽  
Organic Matter Stabilization ◽  
Global Carbon

<p>Polar soils play a key role in global carbon circulation and stabilization as they contain maximum stocks of soil organic matter (SOM) within the whole pedosphere. Cold climate and active layer dynamics result in the stabilization of essential amounts of organic matter in soils, biosediments, and grounds of the polar biome. Chemical composition of soil organic carbon (SOC) determines its decomposability and may affect soil organic matter stabilization (SOM) rate (Beyer, 1995). This is quite important for understanding variability in SOC pools and stabilization rate in context of changes in plant cover or climate (Rossi et al. 2016). <sup>13</sup>C nuclear magnetic resonance spectroscopy, which provides detailed information on diversity of structural composition of humic acids and SOM, may also be used to study the SOM dynamics under decomposition and humification proceses (Kogel-Knabner, 1997; Zech et al., 1997). This study aims to characterize molecular organization of the humic acids, isolated from various permafrost-affected soils of Yamal region and to assess the potential vulnerability of soils organic matter in context of possible mineralization processes. Organic carbon stocks for studied area were 7.85 ± 2.24 kg m-2 (for 0-10 cm layer), 14.97 ± 5.53 kg m-2 (for 0-30 cm), 23.99 ± 8.00 kg m-2 (for 0-100 cm). Results of solid-state 13C-NMR spectrometry showed low amounts of aromatic components in studied soils. All studied humic powders are characterized by predominance of aliphatic structures, and also carbohydrates, polysaccharides, ethers and amino acids. High content of aliphatic fragments in studied humic acids shows their similarity fulvic acids. Low level of aromaticity reflects the accumulation in soil of lowly decomposed organic matter due to cold temperatures. Our results provide further evidence of high vulnerability and sensitivity of permafrost-affected soils organic matter to Arctic warming. Consequently, these soils may play a crucial role in global carbon balance under effects of climate warming.</p>

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