scholarly journals Dynamics of deep soil carbon – insights from <sup>14</sup>C time series across a climatic gradient

2019 ◽  
Vol 16 (16) ◽  
pp. 3233-3246 ◽  
Author(s):  
Tessa Sophia van der Voort ◽  
Utsav Mannu ◽  
Frank Hagedorn ◽  
Cameron McIntyre ◽  
Lorenz Walthert ◽  
...  
Keyword(s):  
Time Series ◽  
Soil Carbon ◽  
Turnover Time ◽  
Climatic Gradient ◽  
Deep Soil ◽  
Dynamic Component ◽  
Soil C ◽  
Time Estimates ◽  
Terrestrial Carbon Cycle ◽  
Water Extractable Organic Carbon

Abstract. Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest as it represents large stocks and its turnover times remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ∼ 1–9 ∘C) gradient are determined using time-series (∼20 years) 14C data from bulk soil and water-extractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last 2 decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. Turnover time estimates of both the bulk and WEOC pool show that the latter cycles up to a magnitude faster than the former. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning WEOC pool across the climatic gradient, implies that there likely is a dynamic component of carbon in the deep soil. Precipitation and bedrock type appear to exert a stronger influence on soil C turnover time and stocks as compared to temperature.

scholarly journals Dynamics of deep soil carbon – insights from <sup>14</sup>C time-series across a climatic gradient

2018 ◽  
Author(s):  
Tessa Sophia van der Voort ◽  
Utsav Mannu ◽  
Frank Hagedorn ◽  
Cameron McIntyre ◽  
Lorenz Walthert ◽  
...  
Keyword(s):  
Time Series ◽  
Soil Carbon ◽  
Turnover Time ◽  
Climatic Gradient ◽  
Turnover Rates ◽  
Deep Soil ◽  
Dynamic Component ◽  
Soil C ◽  
Terrestrial Carbon Cycle ◽  
Water Extractable Organic Carbon

Abstract. Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest, as it represents large stocks and its turnover rates remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ~ 1–9 °C) gradient are determined using time-series (~ 20 years) 14C data from bulk soil and water-extractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last two decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. We used a numerical model to determine turnover time of the bulk, slow and dynamic pool as well as the size of the dynamic pool. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning over WEOC pool and sizeable dynamic fraction at depth across the climatic gradient implies that there likely is a dynamic component of carbon in the deep soil. Precipitation appears to exert a stronger influence on soil C dynamics than temperature. Overall, geology seems to impact the carbon cycling in three key ways: (1) bedrock-derived (petrogenic) carbon can comprise an important component of the soil carbon pool even at relatively shallow depths (< 1 m). (2) Bedrock type influences water logging either by its porosity or by determining texture, and (3) rock and soil mineralogy controls C stabilization.

Supplementary material to "Dynamics of deep soil carbon – insights from <sup>14</sup>C time-series across a climatic gradient"

2018 ◽  
Author(s):  
Tessa Sophia van der Voort ◽  
Utsav Mannu ◽  
Frank Hagedorn ◽  
Cameron McIntyre ◽  
Lorenz Walthert ◽  
...  
Keyword(s):  
Time Series ◽  
Soil Carbon ◽  
Climatic Gradient ◽  
Deep Soil ◽  
Supplementary Material

scholarly journals The contribution of deadwood to soil carbon dynamics in contrasting temperate forest ecosystems

2021 ◽  
Author(s):  
V. L. Shannon ◽  
E. I. Vanguelova ◽  
J. I. L. Morison ◽  
L. J. Shaw ◽  
J. M. Clark
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Leaf Litter ◽  
Phenol Oxidase ◽  
Forest Carbon ◽  
Microbial Decomposition ◽  
High Background ◽  
Soil C ◽  
Tea Bag Index ◽  
Water Extractable Organic Carbon

AbstractDeadwood forms a significant carbon pool in forest systems and is a potential source of dissolved organic carbon (DOC) input to soil, yet little is known about how deadwood effects forest soil carbon cycling. Deadwood DOC inputs to soil may be retained through sorption or may prime microbial decomposition of existing organic matter to produce additional DOC. To determine impacts of deadwood on soil C cycling, we analysed surface soil from beneath deadwood or leaf litter only, along chronosequences of stands of lowland oak and upland Sitka spruce. The concentration and quality (by optical indices) of water-extracted soil DOC (water-extractable organic carbon; WEOC), in situ decomposition ‘tea bag index’ (TBI) parameters and enzymatic potential assays (β-D-cellubiosidase, β-glucosidase, β-xylosidase, leucine aminopeptidase, phosphatase, phenol oxidase) were determined. Presence of deadwood significantly (p < 0.05) increased WEOC concentration (~ 1.5 to ~ 1.75 times) in the mineral oak soil but had no effect on WEOC in spruce soils, potentially because spruce deadwood DOC inputs were masked by a high background of WEOC (1168 mg kg−1 soil) and/or were not retained through mineral sorption in the highly organic (~ 90% SOM) soil. TBI and enzyme evidence suggested that deadwood-derived DOC did not impact existing forest carbon pools via microbial priming, possibly due to the more humified/aromatic quality of DOC produced (humification index of 0.75 and 0.65 for deadwood and leaf litter WEOC, respectively). Forest carbon budgets, particularly those for mineral soils, may underestimate the quantity of DOC if derived from soil monitoring that does not include a deadwood component.

scholarly journals Soil Carbon Regulating Ecosystem Services in the State of South Carolina, USA

Land ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 309
Author(s):  
Elena A. Mikhailova ◽  
Hamdi A. Zurqani ◽  
Christopher J. Post ◽  
Mark A. Schlautman ◽  
Gregory C. Post ◽  
...  
Keyword(s):  
South Carolina ◽  
Ecosystem Services ◽  
Soil Carbon ◽  
Soil Depth ◽  
State Level ◽  
The United States ◽  
The State ◽  
Soil C ◽  
Low Country ◽  
Pee Dee

Sustainable management of soil carbon (C) at the state level requires valuation of soil C regulating ecosystem services (ES) and disservices (ED). The objective of this study was to assess the value of regulating ES from soil organic carbon (SOC), soil inorganic carbon (SIC), and total soil carbon (TSC) stocks, based on the concept of the avoided social cost of carbon dioxide (CO2) emissions for the state of South Carolina (SC) in the United States of America (U.S.A.) by soil order, soil depth (0–200 cm), region and county using information from the State Soil Geographic (STATSGO) database. The total estimated monetary mid-point value for TSC in the state of South Carolina was $124.36B (i.e., $124.36 billion U.S. dollars, where B = billion = 109), $107.14B for SOC, and $17.22B for SIC. Soil orders with the highest midpoint value for SOC were: Ultisols ($64.35B), Histosols ($11.22B), and Inceptisols ($10.31B). Soil orders with the highest midpoint value for SIC were: Inceptisols ($5.91B), Entisols ($5.53B), and Alfisols ($5.0B). Soil orders with the highest midpoint value for TSC were: Ultisols ($64.35B), Inceptisols ($16.22B), and Entisols ($14.65B). The regions with the highest midpoint SOC values were: Pee Dee ($34.24B), Low Country ($32.17B), and Midlands ($29.24B). The regions with the highest midpoint SIC values were: Low Country ($5.69B), Midlands ($5.55B), and Pee Dee ($4.67B). The regions with the highest midpoint TSC values were: Low Country ($37.86B), Pee Dee ($36.91B), and Midlands ($34.79B). The counties with the highest midpoint SOC values were Colleton ($5.44B), Horry ($5.37B), and Berkeley ($4.12B). The counties with the highest midpoint SIC values were Charleston ($1.46B), Georgetown ($852.81M, where M = million = 106), and Horry ($843.18M). The counties with the highest midpoint TSC values were Horry ($6.22B), Colleton ($6.02B), and Georgetown ($4.87B). Administrative areas (e.g., counties, regions) combined with pedodiversity concepts can provide useful information to design cost-efficient policies to manage soil carbon regulating ES at the state level.

scholarly journals Spatially Related Sampling Uncertainty in the Assessment of Labile Soil Carbon and Nitrogen in an Irish Forest Plantation

2021 ◽  
Vol 11 (5) ◽  
pp. 2139
Author(s):  
Junliang Zou ◽  
Bruce Osborne
Keyword(s):  
Spatial Variability ◽  
Soil Carbon ◽  
Sampling Effort ◽  
Limited Information ◽  
Sampling Area ◽  
Soil C ◽  
Distribution Maps ◽  
Soil C And N ◽  
C And N ◽  
Highly Correlated

The importance of labile soil carbon (C) and nitrogen (N) in soil biogeochemical processes is now well recognized. However, the quantification of labile soil C and N in soils and the assessment of their contribution to ecosystem C and N budgets is often constrained by limited information on spatial variability. To address this, we examined spatial variability in dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) in a Sitka spruce forest in central Ireland. The results showed moderate variations in the concentrations of DOC and DTN based on the mean, minimum, and maximum, as well as the coefficients of variation. Residual values of DOC and DTN were shown to have moderate spatial autocorrelations, and the nugget sill ratios were 0.09% and 0.10%, respectively. Distribution maps revealed that both DOC and DTN concentrations in the study area decreased from the southeast. The variability of both DOC and DTN increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. The cokriging technique performed better than the ordinary kriging for predictions of DOC and DTN, which are highly correlated. This study provides a statistically based assessment of spatial variations in DOC and DTN and identifies the sampling effort required for their accurate quantification, leading to improved assessments of forest ecosystem C and N budgets.

scholarly journals The undetected loss of aged carbon from boreal mineral soils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Geert Hensgens ◽  
Hjalmar Laudon ◽  
Mark S. Johnson ◽  
Martin Berggren
Keyword(s):  
Organic Carbon ◽  
Boreal Forest ◽  
Soil C ◽  
Earth Systems ◽  
Nuclear Bomb ◽  
C Cycle ◽  
Water Extractable Organic Carbon ◽  
High Lability ◽  
Mineral Soils ◽  
Terrestrial Biomes

AbstractThe boreal forest is among the largest terrestrial biomes on earth, storing more carbon (C) than the atmosphere. Due to rapid climatic warming and enhanced human development, the boreal region may have begun transitioning from a net C sink to a net source. This raises serious concern that old biogenic soil C can be re-introduced into the modern C cycle in near future. Combining bio-decay experiments, mixing models and the Keeling plot method, we discovered a distinct old pre-bomb organic carbon fraction with high biodegradation rate. In total, 34 ± 12% of water-extractable organic carbon (WEOC) in podzols, one of the dominating boreal soil types, consisted of aged (~ 1000 year) labile C. The omission of this aged (i.e., Δ14C depleted) WEOC fraction in earlier studies is due to the co-occurrence with Δ14C enriched modern C formed following 1950s nuclear bomb testing masking its existence. High lability of aged soil WEOC and masking effects of modern Δ14C enriched C suggests that the risk for mobilization and re-introduction of this ancient C pool into the modern C cycle has gone undetected. Our findings have important implications for earth systems models in terms of climate-carbon feedbacks and the future C balance of the boreal forest.

scholarly journals Soil microbial diversity–biomass relationships are driven by soil carbon content across global biomes

2021 ◽  
Author(s):  
Felipe Bastida ◽  
David J. Eldridge ◽  
Carlos García ◽  
G. Kenny Png ◽  
Richard D. Bardgett ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Soil Carbon ◽  
Soil Microbial Communities ◽  
Ecosystem Functions ◽  
Arid Environments ◽  
Soil Microbial Diversity ◽  
Soil Biodiversity ◽  
Soil C ◽  
Soil Microbial ◽  
Biomass Ratio

AbstractThe relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity–biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.

scholarly journals Undervine groundcover substantially increases shallow but not deep soil carbon in a temperate vineyard

2021 ◽  
Vol 313 ◽  
pp. 107362
Author(s):  
Suzanne M. Fleishman ◽  
Hayden W. Bock ◽  
David M. Eissenstat ◽  
Michela Centinari
Keyword(s):  
Soil Carbon ◽  
Deep Soil
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