Spatial variability in terrestrial and aquatic carbon stocks and fluxes in boreal forested catchments

2020 ◽  
Author(s):  
Nora Casson ◽  
Adrienne Ducharme ◽  
Geethani Amarawansha ◽  
Geoff Gunn ◽  
Scott Higgins ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Soil Depth ◽  
Organic C ◽  
Soil C ◽  
C Pools ◽  
Sampling Campaign ◽  
C Stocks ◽  
Doc Export ◽  
Rain Events ◽  
C Pools And Fluxes

<p>Canada’s boreal zone is a complex mosaic of forests, wetlands, streams and lakes.  The pool of carbon (C) stored in each of these ecosystem components is vast, and significant to the global C balance.  However, C pools and fluxes are heterogeneous in time and space, which contributes to uncertainty in predicting how a changing climate will affect the fate of C in these sensitive ecosystems. The objective of this study was to investigate factors controlling spatial variability in soil C stocks and stream C export and assess the sensitivity of these stocks and fluxes to climatic factors. We conducted a detailed examination of soil C stocks and stream dissolved organic C (DOC) export from a 320 ha boreal forested catchment located in northwestern Ontario, Canada. High-frequency stream chemistry and discharge samples were collected from three inflow streams during snowmelt and rain events from 2016-2017. An intensive soil C sampling campaign resulting in 47 surface (0 – 30 cm) samples were collected during the summer of 2019. Stream hysteresis analysis revealed marked differences in flowpaths among sub-catchments during snowmelt and rain events. In the wetland-dominated catchment, near-stream sources contributed most of the DOC export during both rainstorms and snowmelt events, but in upland-dominated catchments, the sources of DOC depended on antecedent moisture conditions. Rainstorms in these catchments following prolonged droughts resulted in DOC flushing from distal regions of the catchment. Soil C stocks were also highly spatially variable, with much of the variability being explained by local-scale factors (e.g. gravel content, soil depth, distance to the nearest ridge). Taken together, these two findings emphasize the need to consider sub-catchment scale variability when calculating C pools and fluxes in boreal catchments. This is also important when predicting how C dynamics will shift in the future as a result of shorter winters, longer droughts and more intense rainstorms.</p>

scholarly journals Characterization of Soil Carbon Stocks in the City of Johannesburg

Land ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 83
Author(s):  
Kelebohile Rose Seboko ◽  
Elmarie Kotze ◽  
Johan van Tol ◽  
George van Zijl
Keyword(s):  
Bulk Density ◽  
Soil Depth ◽  
Soil Productivity ◽  
Rapid Urbanization ◽  
Organic C ◽  
C Stocks ◽  
Shallow Soils ◽  
Deep Soils ◽  
Soc Stocks ◽  
Soil Groups

Soil organic carbon (SOC) is a crucial indicator of soil health and soil productivity. The long-term implications of rapid urbanization on sustainability have, in recent years, raised concern. This study aimed to characterize the SOC stocks in the Johannesburg Granite Dome, a highly urbanized and contaminated area. Six soil hydropedological groups; (recharge (deep), recharge (shallow), responsive (shallow), responsive (saturated), interflow (A/B), and interflow (soil/bedrock)) were identified to determine the vertical distribution of the SOC stocks and assess the variation among the soil groups. The carbon (C) content, bulk density, and soil depth were determined for all soil groups, and thereafter the SOC stocks were calculated. Organic C stocks in the A horizon ranged, on average, from 33.55 ± 21.73 t C ha−1 for recharge (deep) soils to 17.11 ± 7.62 t C ha−1 for responsive (shallow) soils. Higher C contents in some soils did not necessarily indicate higher SOC stocks due to the combined influence of soil depth and bulk density. Additionally, the total SOC stocks ranged from 92.82 ± 39.2 t C ha−1 for recharge (deep) soils to 22.81 ± 16.84 t C ha−1 for responsive (shallow) soils. Future studies should determine the SOC stocks in urban areas, taking diverse land-uses and the presence of iron (Fe) oxides into consideration. This is crucial for understanding urban ecosystem functions.

scholarly journals Effect of deforestation and subsequent land-use management on soil carbon stocks in the South American Chaco

2018 ◽  
Author(s):  
Natalia Andrea Osinaga ◽  
Carina Rosa Álvarez ◽  
Miguel Angel Taboada
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Warm Season ◽  
Native Forest ◽  
Continuous Cropping ◽  
Organic C ◽  
Soil C ◽  
C Stocks ◽  
Chaco Region ◽  
The Impact

Abstract. Abstract. The sub-humid Chaco region of Argentina, originally covered by dry sclerophyll forest, has been subjected to clearing since the end of the '70 and replacement of the forest by no till farming. Land use changes produced a decrease in aboveground carbon stored in forests, but little is known about the impact on soil organic C stocks. The aim of this study was to evaluate soil C stocks and C fractions up to 1 m depth in soils under different land use:  20 yr continuous cropping, warm season grass pasture and native forest in 32 sites distributed over the Chaco region. The organic C stock content up to 1 m depth expressed as equivalent mass varied as follows: forest (119.3 Mg ha−1) > pasture (87.9 Mg ha−1) > continuous cropping (71.9 and 77.3 Mg ha−1), with no impact of the number of years under cropping. The most sensitive organic carbon fraction was the coarse particle fraction (2000 μm–212 μm) at 0–5 cm and 5–20 cm depth layers. Resistant carbon (

Site-level simulations of measurable soil fractions with Millennial Version 2

2021 ◽  
Author(s):  
Rose Abramoff ◽  
Bertrand Guenet ◽  
Haicheng Zhang ◽  
Katerina Georgiou ◽  
Xiaofeng Xu ◽  
...  
Keyword(s):  
Meta Analysis ◽  
C Sequestration ◽  
Current Understanding ◽  
Century Model ◽  
Mineral Association ◽  
Microbial Decomposition ◽  
Organic C ◽  
Soil C ◽  
Soil Fractions ◽  
C Stocks

<p>Soil carbon (C) models are used to predict C sequestration responses to climate and land use change. Yet, the soil models embedded in Earth system models typically do not represent processes that reflect our current understanding of soil C cycling, such as microbial decomposition, mineral association, and aggregation. Rather, they rely on conceptual pools with turnover times that are fit to bulk C stocks and/or fluxes. As measurements of soil fractions become increasingly available, soil C models that represent these measurable quantities can be evaluated more accurately. Here we present Version 2 (V2) of the Millennial model, a soil model developed to simulate C pools that can be measured by extraction or fractionation, including particulate organic C, mineral-associated organic C, aggregate C, microbial biomass, and dissolved organic C. Model processes have been updated to reflect the current understanding of mineral-association, temperature sensitivity and reaction kinetics, and different model structures were tested within an open-source framework. We evaluated the ability of Millennial V2 to simulate total soil organic C (SOC), as well as the mineral-associated and particulate fractions, using three soil fractionation data sets spanning a range of climate and geochemistry in Australia (N=495), Europe (N=176), and across the globe (N=730). Millennial V2 (RMSE = 1.98 – 4.76 kg, AIC = 597 – 1755) generally predicts SOC content better than the widely-used Century model (RMSE = 2.23 – 4.8 kg, AIC = 584 – 2271), despite an increase in process complexity and number of parameters. Millennial V2 reproduces between-site variation in SOC across a gradient of plant productivity, and predicts SOC turnover times similar to those of a global meta-analysis. Millennial V2 updates the conceptual Century model pools and processes and represents our current understanding of the roles that microbial activity, mineral association and aggregation play in soil C sequestration.</p>

Land‐use change with pasture and short rotation eucalypts impacts the soil C emissions and organic C stocks in the Cerrado biome

2020 ◽  
Vol 31 (7) ◽  
pp. 909-923 ◽  
Author(s):  
Rafael da Silva Teixeira ◽  
Ricardo Cardoso Fialho ◽  
Daniela Cristina Costa ◽  
Rodrigo Nogueira Sousa ◽  
Rafael Silva Santos ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Organic C ◽  
Soil C ◽  
Cerrado Biome ◽  
Short Rotation ◽  
C Stocks

scholarly journals Evaluation of terrestrial pan-Arctic carbon cycling using a data-assimilation system

2019 ◽  
Vol 10 (2) ◽  
pp. 233-255 ◽  
Author(s):  
Efrén López-Blanco ◽  
Jean-François Exbrayat ◽  
Magnus Lund ◽  
Torben R. Christensen ◽  
Mikkel P. Tamstorf ◽  
...  
Keyword(s):  
The Arctic ◽  
Soil Organic C ◽  
Area Index ◽  
Organic C ◽  
Soil C ◽  
Transit Times ◽  
C Cycle ◽  
C Stocks ◽  
Data Assimilation System ◽  
Assimilation System

Abstract. There is a significant knowledge gap in the current state of the terrestrial carbon (C) budget. Recent studies have highlighted a poor understanding particularly of C pool transit times and of whether productivity or biomass dominate these biases. The Arctic, accounting for approximately 50 % of the global soil organic C stocks, has an important role in the global C cycle. Here, we use the CARbon DAta MOdel (CARDAMOM) data-assimilation system to produce pan-Arctic terrestrial C cycle analyses for 2000–2015. This approach avoids using traditional plant functional type or steady-state assumptions. We integrate a range of data (soil organic C, leaf area index, biomass, and climate) to determine the most likely state of the high-latitude C cycle at a 1∘ × 1∘ resolution and also to provide general guidance about the controlling biases in transit times. On average, CARDAMOM estimates regional mean rates of photosynthesis of 565 g C m−2 yr−1 (90 % confidence interval between the 5th and 95th percentiles: 428, 741), autotrophic respiration of 270 g C m−2 yr−1 (182, 397) and heterotrophic respiration of 219 g C m−2 yr−1 (31, 1458), suggesting a pan-Arctic sink of −67 (−287, 1160) g Cm−2 yr−1, weaker in tundra and stronger in taiga. However, our confidence intervals remain large (and so the region could be a source of C), reflecting uncertainty assigned to the regional data products. We show a clear spatial and temporal agreement between CARDAMOM analyses and different sources of assimilated and independent data at both pan-Arctic and local scales but also identify consistent biases between CARDAMOM and validation data. The assimilation process requires clearer error quantification for leaf area index (LAI) and biomass products to resolve these biases. Mapping of vegetation C stocks and change over time and soil C ages linked to soil C stocks is required for better analytical constraint. Comparing CARDAMOM analyses to global vegetation models (GVMs) for the same period, we conclude that transit times of vegetation C are inconsistently simulated in GVMs due to a combination of uncertainties from productivity and biomass calculations. Our findings highlight that GVMs need to focus on constraining both current vegetation C stocks and net primary production to improve a process-based understanding of C cycle dynamics in the Arctic.

scholarly journals Spatial patterns in soil organic matter dynamics are shaped by mycorrhizosphere interactions in a treeline forest

2019 ◽  
Vol 447 (1-2) ◽  
pp. 521-535
Author(s):  
Nina L. Friggens ◽  
Thomas J. Aspray ◽  
Thomas C. Parker ◽  
Jens-Arne Subke ◽  
Philip A. Wookey
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Spatial Scales ◽  
Mountain Birch ◽  
Organic C ◽  
Soil C ◽  
Soil Organic Matter Dynamics ◽  
C Stocks ◽  
Organic Matter Dynamics ◽  
Individual Trees

Abstract Aims In the Swedish sub-Arctic, mountain birch (Betula pubescens ssp. czerepanovii) forests mediate rapid soil C cycling relative to adjacent tundra heaths, but little is known about the role of individual trees within forests. Here we investigate the spatial extent over which trees influence soil processes. Methods We measured respiration, soil C stocks, root and mycorrhizal productivity and fungi:bacteria ratios at fine spatial scales along 3 m transects extending radially from mountain birch trees in a sub-Arctic ecotone forest. Root and mycorrhizal productivity was quantified using in-growth techniques and fungi:bacteria ratios were determined by qPCR. Results Neither respiration, nor root and mycorrhizal production, varied along transects. Fungi:bacteria ratios, soil organic C stocks and standing litter declined with increasing distance from trees. Conclusions As 3 m is half the average size of forest gaps, these findings suggest that forest soil environments are efficiently explored by roots and associated mycorrhizal networks of B. pubescens. Individual trees exert influence substantially away from their base, creating more uniform distributions of root, mycorrhizal and bacterial activity than expected. However, overall rates of soil C accumulation do vary with distance from trees, with potential implications for spatio-temporal soil organic matter dynamics and net ecosystem C sequestration.

Quantifying total and labile pools of soil organic carbon in cultivated and uncultivated soils in eastern India

Soil Research ◽  
2018 ◽  
Vol 56 (4) ◽  
pp. 413 ◽  
Author(s):  
Kumari Priyanka ◽  
Anshumali
Keyword(s):  
Land Use ◽  
Function Analysis ◽  
Land Use Changes ◽  
C Sequestration ◽  
Sensitivity Index ◽  
Organic C ◽  
Soil C ◽  
C Pools ◽  
The Impact ◽  
Land Use Practices

Loss of labile carbon (C) fractions yields information about the impact of land-use changes on sources of C inputs, pathways of C losses and mechanisms of soil C sequestration. This study dealt with the total organic C (TOC) and labile C pools in 40 surface soil samples (0–15 cm) collected from four land-use practices: uncultivated sites and rice–wheat, maize–wheat and sugarcane agro-ecosystems. Uncultivated soils had a higher total C pool than croplands. The soil inorganic C concentrations were in the range of 0.7–1.4 g kg–1 under different land-use practices. Strong correlations were found between TOC and all organic C pools, except water-extractable organic C and mineralisable C. The sensitivity index indicated that soil organic C pools were susceptible to changes in land-use practices. Discriminant function analysis showed that the nine soil variables could distinguish the maize–wheat and rice–wheat systems from uncultivated and sugarcane systems. Finally, we recommend crop rotation practices whereby planting sugarcane replenishes TOC content in soils.

Soil acidification and the carbon cycle in a cropping soil of north-eastern Victoria

Soil Research ◽  
1998 ◽  
Vol 36 (2) ◽  
pp. 273 ◽  
Author(s):  
W. J. Slattery ◽  
D. G. Edwards ◽  
L. C. Bell ◽  
D. R. Coventry ◽  
K. R. Helyar
Keyword(s):  
Soil Depth ◽  
Organic C ◽  
Soil Layers ◽  
Soil C ◽  
Soil Zone ◽  
North Eastern ◽  
Soil Buffering ◽  
The Impact ◽  
Total Organic C

Changes in soil organic matter were determined for a long-term (1975–95) experiment at the Rutherglen Research Institute in north-eastern Victoria. The crop rotations in this experiment were continuous lupins (LL) and continuous wheat (WW). The soil at this site was a solodic or Yellow Dermosol with a soil pH of 6·08 (pH in 0·01 М CaCl2 1 : 5) in 1975 in the surface 10 cm, which had declined by 0·8 and 1·5 pH units for WW and LL, respectively, in the 0–20 cm soil zone by 1992. Acidification rates decreased with increasing soil depth. The acidification rate in the 0–60 cm soil zone was 12·5 kmol(H+)/ha·year for the LL rotation and 4·6 kmol(H+)/ha·year for the WW rotation. The amount of CaCO3 required to neutralise the acidification of wheat-lupin rotations as calculated in this paper was up to 3·8 t/ha ·10 years for a WLWL rotation or 3 ·3 t/ha ·10 years for a WWL rotation; these amounts are significantly higher than previously reported rates. In this paper, we calculate the impact of changes in soil carbon (C) status over time, and therefore soil buffering, on the rates of acidification in incremental soil layers to a depth of 60 cm. Total organic C for these rotations in 1992 was 1·12% for WW and 1·17% for LL in the 0–10 cm soil zone. An investigation of the humic and fulvic acid fractions of these 2 rotations to a depth of 60 cm showed that the LL rotation had significantly higher (P < 0·05) C at depth than the WW rotation. Acidification due to the net decrease in soil C over the 15-year study period plus acidification due to the alkali removed in the seed was calculated to be –4·88 kmol(H+)/ha·year for the LL rotation and –6·52 kmol(H+)/ha·year for the WW rotation.

Changes in soil carbon and soil nitrogen after tree clearing in the semi-arid rangelands of Queensland

2005 ◽  
Vol 53 (7) ◽  
pp. 639 ◽  
Author(s):  
B. P. Harms ◽  
R. C. Dalal ◽  
A. P. Cramp
Keyword(s):  
Soil Carbon ◽  
Soil Depth ◽  
Woody Debris ◽  
Soil Phosphorus ◽  
Basal Area ◽  
Clay Content ◽  
Strongly Correlated ◽  
Soil N ◽  
Soil C ◽  
C Stocks

Changes in soil carbon (C) and nitrogen (N) stocks following tree clearing were estimated at 32 rangeland sites in central and southern Queensland by using paired-site sampling. When corrected for soil bulk-density differences at each site, average soil C across all sites decreased after tree clearing by 8.0% for 0–0.3-m soil depth, and by 5.4% for 0–1.0-m depth; there were corresponding declines in soil C of 2.5 and 3.5tha–1, respectively. Mean soil C stocks (excluding surface litter, extractable roots and coarse charcoal) at uncleared sites were 29.5tha–1 for 0–0.3-m soil depth, and 62.5tha–1 for 0–1.0-m depth. Mean soil C stocks (0–0.3m) were 41% of the mean total C for the soil–plant system (soil + litter/woody debris + stand biomass) at uncleared sites. Soil C decline (0–0.3m) accounted for approximately 7% of the average total C lost because of land clearing across all sites. Soil C stocks at uncleared sites were correlated with tree basal area, clay content and soil phosphorus (P) content. Changes in soil C after tree clearing were strongly correlated to initial soil C contents at the uncleared sites, and were associated with particular vegetation groups and soil types. Changes in soil N were strongly correlated with changes in soil C; however, the average change in soil N across all sites was not significant. Given the size of the C and N pools in rangeland soils, the factors that influence soil C and soil N dynamics in rangeland systems need to be better understood for the effective management of C stocks in these soils.

Estimates of soil organic carbon stocks in central Canada using three different approaches

2002 ◽  
Vol 32 (5) ◽  
pp. 805-812 ◽  
Author(s):  
J S Bhatti ◽  
M J Apps ◽  
C Tarnocai
Keyword(s):  
Surface Layer ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Soil Depth ◽  
Peat Soil ◽  
Regression Line ◽  
Organic C ◽  
Soil C ◽  
Total Soil

This study compared three estimates of carbon (C) contained both in the surface layer (0–30 cm) and the total soil pools at polygon and regional scales and the spatial distribution in the three prairie provinces of western Canada (Alberta, Saskatchewan, and Manitoba). The soil C estimates were based on data from (i) analysis of pedon data from both the Boreal Forest Transect Case Study (BFTCS) area and from a national-scale soil profile database; (ii) the Canadian Soil Organic Carbon Database (CSOCD), which uses expert estimation based on soil characteristics; and (iii) model simulations with the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS2). At the polygon scale, good agreement was found between the CSOCD and pedon (the first method) total soil carbon values. Slightly higher total soil carbon values obtained from BFTCS averaged pedon data (the first method), as indicated by the slope of the regression line, may be related to micro- and meso-scale geomorphic and microclimate influences that are not accounted for in the CSOCD. Regional estimates of organic C from these three approaches for upland forest soils ranged from 1.4 to 7.7 kg C·m–2 for the surface layer and 6.2 to 27.4 kg C·m–2 for the total soil. In general, the CBM-CFS2 simulated higher soil C content compared with the field observed and CSOCD soil C estimates, but showed similar patterns in the total soil C content for the different regions. The higher soil C content simulated with CBM-CFS2 arises in part because the modelled results include forest floor detritus pool components (such as coarse woody debris, which account for 4–12% of the total soil pool in the region) that are not included in the other estimates. The comparison between the simulated values (the third method) and the values obtained from the two empirical approaches (the first two methods) provided an independent test of CBM-CFS2 soil simulations for upland forests soils. The CSOCD yielded significantly higher C content for peatland soils than for upland soils, ranging from 14.6 to 28 kg C·m–2 for the surface layer and 60 to 181 kg C·m–2 for the total peat soil depth. All three approaches indicated higher soil carbon content in the boreal zone than in other regions (subarctic, grassland).

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