scholarly journals Disentangling residence time and temperature sensitivity of microbial decomposition in a global soil carbon model

2014 ◽  
Vol 11 (23) ◽  
pp. 6999-7008 ◽  
Author(s):  
J.-F. Exbrayat ◽  
A. J. Pitman ◽  
G. Abramowitz
Keyword(s):  
Soil Carbon ◽  
Residence Time ◽  
Carbon Balance ◽  
Carbon Stocks ◽  
Historical Period ◽  
Microbial Decomposition ◽  
Total Soil ◽  
Industrial Soil ◽  
The Future ◽  
The Impact

Abstract. Recent studies have identified the first-order representation of microbial decomposition as a major source of uncertainty in simulations and projections of the terrestrial carbon balance. Here, we use a reduced complexity model representative of current state-of-the-art models of soil organic carbon decomposition. We undertake a systematic sensitivity analysis to disentangle the effect of the time-invariant baseline residence time (k) and the sensitivity of microbial decomposition to temperature (Q10) on soil carbon dynamics at regional and global scales. Our simulations produce a range in total soil carbon at equilibrium of ~ 592 to 2745 Pg C, which is similar to the ~ 561 to 2938 Pg C range in pre-industrial soil carbon in models used in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). This range depends primarily on the value of k, although the impact of Q10 is not trivial at regional scales. As climate changes through the historical period, and into the future, k is primarily responsible for the magnitude of the response in soil carbon, whereas Q10 determines whether the soil remains a sink, or becomes a source in the future mostly by its effect on mid-latitude carbon balance. If we restrict our simulations to those simulating total soil carbon stocks consistent with observations of current stocks, the projected range in total soil carbon change is reduced by 42% for the historical simulations and 45% for the future projections. However, while this observation-based selection dismisses outliers, it does not increase confidence in the future sign of the soil carbon feedback. We conclude that despite this result, future estimates of soil carbon and how soil carbon responds to climate change should be more constrained by available data sets of carbon stocks.

scholarly journals Disentangling residence time and temperature sensitivity of microbial decomposition in a global soil carbon model

2014 ◽  
Vol 11 (3) ◽  
pp. 4995-5021 ◽  
Author(s):  
J.-F. Exbrayat ◽  
A. J. Pitman ◽  
G. Abramowitz
Keyword(s):  
Soil Carbon ◽  
Residence Time ◽  
Carbon Balance ◽  
Coupled Model ◽  
Historical Period ◽  
Microbial Decomposition ◽  
Total Soil ◽  
Industrial Soil ◽  
The Future ◽  
The Impact

Abstract. Recent studies have identified the first-order parameterization of microbial decomposition as a major source of uncertainty in simulations and projections of the terrestrial carbon balance. Here, we use a reduced complexity model representative of the current state-of-the-art parameterization of soil organic carbon decomposition. We undertake a systematic sensitivity analysis to disentangle the effect of the time-invariant baseline residence time (k) and the sensitvity of microbial decomposition to temperature (Q10) on soil carbon dynamics at regional and global scales. Our simulations produce a range in total soil carbon at equilibrium of ~ 592 to 2745 Pg C which is similar to the ~ 561 to 2938 Pg C range in pre-industrial soil carbon in models used in the fifth phase of the Coupled Model Intercomparison Project. This range depends primarily on the value of k, although the impact of Q10 is not trivial at regional scales. As climate changes through the historical period, and into the future, k is primarily responsible for the magnitude of the response in soil carbon, whereas Q10 determines whether the soil remains a sink, or becomes a source in the future mostly by its effect on mid-latitudes carbon balance. If we restrict our simulations to those simulating total soil carbon stocks consistent with observations of current stocks, the projected range in total soil carbon change is reduced by 42% for the historical simulations and 45% for the future projections. However, while this observation-based selection dismisses outliers it does not increase confidence in the future sign of the soil carbon feedback. We conclude that despite this result, future estimates of soil carbon, and how soil carbon responds to climate change should be constrained by available observational data sets.

scholarly journals Modeling relevant factors and covariates of carbon stock changes in peatlands using a hierarchical linear mixed modeling approach

2020 ◽  
Author(s):  
Kilian Walz ◽  
Kenneth A Byrne ◽  
David Wilson ◽  
Florence Renou-Wilson
Keyword(s):  
Soil Carbon ◽  
Environmental Protection Agency ◽  
Land Surface ◽  
Carbon Stock ◽  
Dimensional Space ◽  
Carbon Stocks ◽  
Carbon Distribution ◽  
Soil Carbon Stock ◽  
Modeling Approach ◽  
The Impact

<p>While peatlands constitute the largest soil carbon stock in Ireland with 75% of soil carbon stored in an area covering an estimated 20% of the land surface, carbon stocks of peatlands are affected by past and present disturbances related to various land uses. Afforestation, grazing and peat extraction for energy and horticultural use often are major drivers of peatland soil degradation. A comparative assessment of the impact of land disturbance on peatland soil carbon stocks on a national scale has been lacking so far. Current research, funded by the Irish Environmental Protection Agency (EPA), addresses this issue with the goal to fill various gaps related to mapping and modeling changes of soil carbon stock in Irish peatlands. Data from the first nationwide peatland survey forms the basis for this study, in which the influence of different factors and covariates on soil carbon distribution in peatlands is examined. After data exploratory analysis, a mixed linear modeling approach is tested for its suitability to explain peatland soil carbon distribution within the Republic of Ireland. Parameters are identified which are responsible for changes across the country. In addition, model performance to map peat soil carbon stock within a three-dimensional space is evaluated.</p>

scholarly journals Response of microbial decomposition to spin-up explains CMIP5 soil carbon range until 2100

2014 ◽  
Vol 7 (6) ◽  
pp. 2683-2692 ◽  
Author(s):  
J.-F. Exbrayat ◽  
A. J. Pitman ◽  
G. Abramowitz
Keyword(s):  
Soil Carbon ◽  
Carbon Storage ◽  
Land Surface ◽  
Coupled Model ◽  
Surface Fluxes ◽  
Cmip5 Models ◽  
Historical Period ◽  
Microbial Decomposition ◽  
Transient Simulations ◽  
Business As Usual

Abstract. Soil carbon storage simulated by the Coupled Model Intercomparison Project (CMIP5) models varies 6-fold for the present day. Here, we confirm earlier work showing that this range already exists at the beginning of the CMIP5 historical simulations. We additionally show that this range is largely determined by the response of microbial decomposition during each model's spin-up procedure from initialization to equilibration. The 6-fold range in soil carbon, once established prior to the beginning of the historical period (and prior to the beginning of a CMIP5 simulation), is then maintained through the present and to 2100 almost unchanged even under a strong business-as-usual emissions scenario. We therefore highlight that a commonly ignored part of CMIP5 analyses – the land surface state achieved through the spin-up procedure – can be important for determining future carbon storage and land surface fluxes. We identify the need to better constrain the outcome of the spin-up procedure as an important step in reducing uncertainty in both projected soil carbon and land surface fluxes in CMIP5 transient simulations.

A preliminary assessment of the impact of landslide, earthflow, and gully erosion on soil carbon stocks in New Zealand

Geomorphology ◽  
2018 ◽  
Vol 307 ◽  
pp. 93-106 ◽  
Author(s):  
Les Basher ◽  
Harley Betts ◽  
Ian Lynn ◽  
Mike Marden ◽  
Stephen McNeill ◽  
...  
Keyword(s):  
New Zealand ◽  
Soil Carbon ◽  
Carbon Stocks ◽  
Gully Erosion ◽  
Preliminary Assessment ◽  
Soil Carbon Stocks ◽  
The Impact

scholarly journals Permafrost carbon−climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics

2015 ◽  
Vol 112 (12) ◽  
pp. 3752-3757 ◽  
Author(s):  
Charles D. Koven ◽  
David M. Lawrence ◽  
William J. Riley
Keyword(s):  
Soil Nitrogen ◽  
Carbon Balance ◽  
Nitrogen Availability ◽  
Nitrogen Dynamics ◽  
Permafrost Region ◽  
Deep Soil ◽  
Surface Soils ◽  
Permafrost Thaw ◽  
The Future ◽  
The Impact

Permafrost soils contain enormous amounts of organic carbon whose stability is contingent on remaining frozen. With future warming, these soils may release carbon to the atmosphere and act as a positive feedback to climate change. Significant uncertainty remains on the postthaw carbon dynamics of permafrost-affected ecosystems, in particular since most of the carbon resides at depth where decomposition dynamics may differ from surface soils, and since nitrogen mineralized by decomposition may enhance plant growth. Here we show, using a carbon−nitrogen model that includes permafrost processes forced in an unmitigated warming scenario, that the future carbon balance of the permafrost region is highly sensitive to the decomposability of deeper carbon, with the net balance ranging from 21 Pg C to 164 Pg C losses by 2300. Increased soil nitrogen mineralization reduces nutrient limitations, but the impact of deep nitrogen on the carbon budget is small due to enhanced nitrogen availability from warming surface soils and seasonal asynchrony between deeper nitrogen availability and plant nitrogen demands. Although nitrogen dynamics are highly uncertain, the future carbon balance of this region is projected to hinge more on the rate and extent of permafrost thaw and soil decomposition than on enhanced nitrogen availability for vegetation growth resulting from permafrost thaw.

Conifer wood biochar as an amendment for agricultural soils in South-Tyrol: impact on greenhouse gases emissions and soil carbon stocks

2020 ◽  
Author(s):  
Irene Criscuoli ◽  
Maurizio Ventura ◽  
Katja Wiedner ◽  
Bruno Glaser ◽  
Pietro Panzacchi ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Soil Carbon ◽  
Temperature Sensitivity ◽  
Carbon Stocks ◽  
First Year ◽  
South Tyrol ◽  
The Impact ◽  
Conifer Wood ◽  
Over Time

<p>Biochar is a carbonaceous material produced through the pyro-gasification of biomass. In the last decade, biochar has been proposed as a soil amendment because it can improve soil physico-chemical properties and carbon stocks, contributing to climate change mitigation.</p><p>In the framework of the Wood-Up project (Optimization of WOOD gasification chain in South Tyrol to prodUce bioenergy and other high-value green Products to enhance soil fertility and mitigate climate change, FESR1028), we studied the impact of conifer wood biochar on the emissions of the main greenhouse gases (GHGs) from the soil: carbon dioxide (CO<sub>2</sub>), nitrous oxide (N<sub>2</sub>O) and methane (CH<sub>4</sub>), as well as on the soil carbon stock of agricultural fields in South Tyrol.</p><p>In May 2017, 25 and 50 t ha<sup>-1</sup> of pure biochar and biochar mixed with compost (45 t ha<sup>-1</sup>), were applied to the soil of a vineyard near Merano (South-Tyrol, northern Italy) following a randomized block experimental design with four replicates per treatment.</p><p>Soil GHGs fluxes were monitored from June 2017 until December 2019. Fluxes were measured, in real time, with a high-resolution portable multi-gas analyzer based on cavity ring-down spectroscopy technology (Picarro inc., Santa Clara, CA, USA) connected to an automated dynamic chambers system (Eosense Inc., Dartmouth, NS, Canada). Gas emissions were measured monthly and were related to soil temperature and moisture to evaluate the impact of treatments on the sensitivity of GHGs fluxes to environmental parameters. The stability of conifer wood biochar in soil was assessed through the quantification of the Benzene PolyCarboxylic Acids (BPCA), specific biomarkers of black carbon, over time. The BPCA content in the soil was measured before the application of biochar and compost, three weeks after the application and two years later.</p><p>During the first year of experiment, in biochar-amended soils, we observed a reduction of the temperature sensitivity of all GHGs fluxes in comparison to treatments without biochar (control and compost alone). In the second and third year an opposite trend was observed, with an increase of temperature sensitivity of GHGs fluxes in biochar-treated soil. The change of biochar effect over time might be linked to biochar ageing in soil. However, a role of soil moisture cannot be excluded, as it was higher in the first year of experiment. The experimental results will be presented in the broader context of the Wood-Up project.</p>

More extreme El Niño events reduce ocean carbon uptake in the future

2021 ◽  
Author(s):  
Enhui Liao ◽  
Laure Resplandy ◽  
Junjie Liu ◽  
Kevin Bowman
Keyword(s):  
Biogeochemical Model ◽  
Historical Period ◽  
Terrestrial Biosphere ◽  
The Future ◽  
Thermally Driven ◽  
High Emission ◽  
Ocean Carbon ◽  
High Emission Scenario ◽  
Flux Response ◽  
The Impact

<p>El Niño events weaken the strong natural oceanic source of CO<sub>2</sub> in the Tropical Pacific Ocean, partly offsetting the simultaneous release of CO<sub>2</sub> from the terrestrial biosphere during these events. Yet, uncertainties in the magnitude of this ocean response and how it will respond to the projected increase in extreme El Niño in the future (Cai et al., 2014) limit our understanding of the global carbon cycle and its sensitivity to climate. Here, we examine the mechanisms controlling the air-sea CO<sub>2</sub> flux response to El Niño events and how it will evolve in the future, using multidecadal ocean pCO<sub>2</sub> observations in conjunction with CMIP6 Earth system models (ESMs) and a state‐of‐the‐art ocean biogeochemical model. We show that the magnitude, spatial extent, and duration of the anomalous ocean CO<sub>2</sub> drawdown increased with El Niño intensity in the historical period. However, this relationship reverses in the CMIP6 projections under the high emission scenario. ESMs project more intense El Niño events, but weaker CO<sub>2</sub> flux anomalies in the future. This unexpected response is controlled by two factors: a stronger compensation between thermally-driven outgassing and non-thermal drawdown (56% of the signal); and less pronounced wind anomalies limiting the impact of El Niño on air-sea CO<sub>2</sub> exchanges (26% of the signal). El Niños should no longer reinforce the net global oceanic sink in the future, but have a near-neutral effect or even release CO<sub>2</sub> to the atmosphere, reinforcing the concurrent release of CO<sub>2</sub> from the terrestrial biosphere.</p>

scholarly journals What is the impact of human wastewater biosolids (sewage sludge) application on long-term soil carbon sequestration rates? A systematic review protocol

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mike J. Badzmierowski ◽  
Gregory K. Evanylo ◽  
W. Lee Daniels ◽  
Kathryn C. Haering
Keyword(s):  
Carbon Sequestration ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Full Text ◽  
Land Application ◽  
Carbon Stocks ◽  
Soil Organic Carbon Stocks ◽  
The Impact

Abstract Background Human wastewater biosolids, hereafter referred to as biosolids, are produced in significant quantities around the world and often applied to an extensive land mass including agricultural fields, forests, mine lands, and urban areas. Land-application of biosolids has been reported in peer-reviewed and non-peer-reviewed work to change soil organic carbon stocks in varying amounts. Determining the potential of soil organic carbon (SOC) stock change and sequestration from biosolids land application is critical for biosolids producers and users to gain access to carbon credit markets. Our review question is, "what is the impact of biosolids application on long-term soil carbon sequestration rates?” We look to explore this main question with the follow-up, "does biosolids processing methods and characteristics, application method, soil properties, land management and other modifiers affect rates of carbon accumulation from land-applied biosolids?" Methods Searches will be conducted using online databases (i.e., Web of Science Core Collection, CAB Abstracts, Scopus, ProQuest Dissertations & Theses Global), search engines (Google Scholar and Microsoft Academic), and specialist websites to find primary field studies and grey literature of biosolids land-application effects on soil organic carbon stocks. We will use English search terms and predefined inclusion criteria of: (1) a field study of at least 24 months that reports soil organic carbon/matter (SOC/SOM) concentrations/stocks; (2) has two types of treatments: (i) a control (non-intervention AND/OR synthetic fertilizer) AND (ii) a biosolids-based amendment; and (3) information of amendment properties and application dates and rates to estimate the relative contribution of the applied materials to SOC changes. We will screen results in two stages: (1) title and abstract and (2) full text. A 10% subset will be screened by two reviewers for inclusion at the title and abstract level and use a kappa analysis to ensure agreement of at least 0.61. All results in the full text stage will be dual screened. Data will be extracted by one person and reviewed by a second person. Critical appraisal will be used to assess studies’ potential bias and done by two reviewers. A meta-analysis using random effects models will be conducted if sufficient data of high enough quality are extracted.

scholarly journals Linking Vegetation, Soil Carbon Stocks, and Earthworms in Upland Coniferous–Broadleaf Forests

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1179
Author(s):  
Anastasiia I. Kuznetsova ◽  
Anna P. Geraskina ◽  
Natalia V. Lukina ◽  
Vadim E. Smirnov ◽  
Elena V. Tikhonova ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Carbon Stocks ◽  
Mineral Layer ◽  
Forest Zone ◽  
Soil C ◽  
C Stocks ◽  
European Part Of Russia ◽  
Organic Horizons ◽  
Soil Carbon Stocks ◽  
The Impact

Linking vegetation, soil biota, and soil carbon stocks in forests has a high predictive value. The specific aim of this study was to identify the relationships between vegetation, earthworms, and soil carbon stocks in nine types of forests dominating autonomous landscape positions in a coniferous–broadleaf forest zone of the European part of Russia. Mountain forests were selected in the Northwest Caucasus, while plain forests were selected in Bryansk Polesie and on the Moskva-Oka plain. One-way analysis of variance (ANOVA) and v-tests were used to assess the impact of different factors on soil C stocks. To assess the contribution of vegetation, litter quality, and earthworms to variation of carbon stocks in organic (FH-layer) and mineral layer (0–50 cm), the method of hierarchical partitioning was performed. The highest C stocks in the organic horizons were associated with the low-quality litter, i.e., with a low base saturation, high acidity, and wide C/N ratio. The highest soil C stocks in the mineral layers were found in mixed forests with the highest richness of plant species, producing litterfall of different quality. The С stock in the organic horizon was negatively related to the biomass of worms that process the litter, while the carbon stock in the mineral layers was positively related to the biomass of worms whose life activity is related to the mineral layers. These findings demonstrated the substantial influence of plants producing a litter of different quality, and of earthworms, belonging to different functional groups, on soil С stocks in coniferous–broadleaf forests.

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