scholarly journals A field-based method for simultaneous measurements of the <sup>18</sup>O and <sup>13</sup>C soil CO<sub>2</sub> efflux

2004 ◽  
Vol 1 (1) ◽  
pp. 1-25 ◽  
Author(s):  
B. Mortazavi ◽  
J. L. Prater ◽  
J. P. Chanton
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
Soil Surface ◽  
Co2 Concentration ◽  
Vertical Gradient ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Fractionation Factor ◽  
Keeling Plots

Abstract. Three approaches for determining the stable isotopic composition (13C and 18O) of soil CO2 efflux were compared. A new technique employed mini-towers, constructed of open topped piping, that were placed on the soil surface to collect soil-emitted CO2. Samples were collected along a vertical gradient and analyzed for CO2 concentration and isotopic composition. These data were then used to produce a Keeling plot to determine the 18O and 13C of CO2 emitted from the soil. These results were then compared to the 18O and 13C of soil respired CO2 measured with two other techniques: (1) flux chambers and (2) estimation from the application of the diffusional fractionation factor to measured values of belowground soil 18O CO2 and to CO2 in equilibrium with soil water 18O. Mini-tower 18O Keeling plots were linear and highly significant (0.81<r2<0.96), in contrast to chamber 18O Keeling plots, which showed significant curvature, necessitating the use of a mass balance to calculate the 18O of respired CO2. In the chambers, the values determined for the 18O of soil respired CO2 approached the value of CO2 in equilibrium with surficial soil water, and the results were significantly 18O enriched relative to the mini-tower results and the 18O of soil CO2 efflux determined from soil CO2. There were close agreements between the three methods for the determination of the 13C of soil efflux CO2. Results suggest that the mini-towers can be effectively used in the field for determining the 18O and the 13C of soil respired CO2.

scholarly journals A field-based method for simultaneous measurements of the δ<sup>18</sup>O and δ<sup>13</sup>C of soil CO<sub>2</sub> efflux

2004 ◽  
Vol 1 (1) ◽  
pp. 1-9 ◽  
Author(s):  
B. Mortazavi ◽  
J. L. Prater ◽  
J. P. Chanton
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
Soil Surface ◽  
Co2 Concentration ◽  
Vertical Gradient ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Fractionation Factor ◽  
Keeling Plots ◽  
Δ18o And Δ13c

Abstract. Three approaches for determining the stable isotopic composition (δ13C and δ18O) of soil CO efflux were compared. A new technique employed mini-towers, constructed of open-topped piping, that were placed on the soil surface to collect soil-emitted CO2. Samples were collected along a vertical gradient and analyzed for CO2 concentration and isotopic composition. These data were then used to produce Keeling plots to determine the δ18O and δ13C of CO2 emitted from the soil. These results were then compared to the δ18O and δ13C of soil-respired CO2 measured with two other techniques: (1) flux chambers and (2) estimation from the application of the diffusional fractionation factor to measured values of below ground soil CO2 and to CO2 in equilibrium with soil water δ18O. Mini-tower δ18O Keeling plots were linear and highly significant (0.81< r 2 > 0.96), in contrast to chamber δ18O Keeling plots, which showed significant curvature, necessitating the use of a mass balance to calculate the δ18O of respired CO2. In the chambers, the values determined for the δ18O of soil respired CO2 approached the value of CO2 in equilibrium with surficial soil water, and the results were significantly δ18O enriched relative to the mini-tower results and the δ18O of soil CO2 efflux determined from soil CO2. There were close agreements between the three methods for the determination of the δ13C of soil efflux CO2. Results suggest that the mini-towers can be effectively used in the field for determining the δ18O and the δ13C of soil-respired CO2.

Soil CO2 concentration and efflux from three forests in subtropical China

Soil Research ◽  
2012 ◽  
Vol 50 (4) ◽  
pp. 328 ◽  
Author(s):  
Lixia Zhou ◽  
Shenglei Fu ◽  
Mingmao Ding ◽  
Zhigang Yi ◽  
Weimin Yi
Keyword(s):  
Soil Depth ◽  
Soil Surface ◽  
Co2 Concentration ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Subtropical China ◽  
Mean Values ◽  
Soil Co2 Concentration ◽  
The Mean

Measurements of soil CO2 efflux and soil CO2 concentration concurrently are important for understanding the mechanism and regulation of CO2 in the soil. We have analysed CO2 concentration in a soil profile and soil CO2 efflux in three typical forests in subtropical China: monsoon evergreen broad-leaved forest (BF, 400 years old), pine and broad-leaved mixed forest (MF, 80 years old), and pine forest (PF, 70 years old). A portable soil CO2 sampler of simple sample operation was designed and used. The seasonal patterns of soil surface CO2 efflux and soil CO2 concentration were observed, and were positively correlated with rainfall, soil temperature, and moisture. The mean values of soil CO2 concentrations at the 15, 30, 45, and 60 cm soil depth were higher in BF (3368–9243 μL L–1) than in MF (1495–7662 μL L–1) and PF (1566–5730 μL L–1), while the mean values of soil surface CO2 efflux (Rsurface) were 0.55 ± 0.11 g m–2 h–1 in BF, 0.52 ± 0.10 g m–2 h–1 in MF, and 0.45 ± 0.07 g m–2 h–1 in PF. Soil CO2 concentration and Rsurface increased gradually with the age of the forests, but the incremental increase in soil CO2 concentration will be greater than that of Rsurface in MF and PF compared with BF. The data suggested that, although older forests have more C, younger forests probably will sequester C as CO2 faster than older forests.

scholarly journals Soil CO2 efflux in a beech forest: dependence on soil temperature and soil water content

1999 ◽  
Vol 56 (3) ◽  
pp. 221-226 ◽  
Author(s):  
Daniel Epron ◽  
Lætitia Farque ◽  
Éric Lucot ◽  
Pierre-Marie Badot
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Beech Forest ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Forest Dependence

Root exclusion through trenching does not affect the isotopic composition of soil CO2 efflux

2008 ◽  
Vol 319 (1-2) ◽  
pp. 1-13 ◽  
Author(s):  
Nicolas Chemidlin Prévost-Bouré ◽  
Jérome Ngao ◽  
Daniel Berveiller ◽  
Damien Bonal ◽  
Claire Damesin ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Root Exclusion

Soil carbon dioxide efflux determined from large undisturbed soil cores collected in different soil management systems

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Eszter Tóth ◽  
Sándor Koós ◽  
Csilla Farkas
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Management ◽  
Measuring Method ◽  
Soil Co2 Efflux ◽  
Management Systems ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Undisturbed Soil

AbstractThe aim of this study was to evaluate a measuring technique for determining soil CO2 efflux from large soil samples having undisturbed structure under controlled laboratory conditions. Further objectives were to use the developed measuring method for comparing soil CO2 efflux from samples, collected in three different soil management systems at various soil water content values. The experimental technique was tested and optimised for timing of sampling by taking air samples after 1, 3 and 6 hours of incubation. Based on the results, the incubation time was set to three hours. The CO2 efflux measured for different soil management systems was the highest in the no-till and the lowest in the ploughing treatment, which was in accordance with measurements on accessible organic carbon for microbes. An increase in CO2 efflux with increasing soil water content was found in the studied soil water content range. Our results indicate that soil respiration rates, measured directly after tillage operations, can highly differ from those measured long after.

scholarly journals Vegetation heterogeneity and landscape position exert strong controls on soil CO<sub>2</sub> efflux in a moist, Appalachian watershed

2014 ◽  
Vol 11 (12) ◽  
pp. 17631-17673 ◽  
Author(s):  
J. W. Atkins ◽  
H. E. Epstein ◽  
D. L. Welsch
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Biogeochemical Cycles ◽  
Soil Co2 Efflux ◽  
Landscape Position ◽  
Temperature Threshold ◽  
Valuable Insight ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Vegetation Heterogeneity

Abstract. In topographically complex watersheds, landscape position and vegetation heterogeneity can alter the soil water regime through both lateral and vertical redistribution, respectively. These alterations of soil moisture may have significant impacts on the spatial heterogeneity of biogeochemical cycles throughout the watershed. To evaluate how landscape position and vegetation heterogeneity affect soil CO2 efflux (FSOIL) we conducted observations across the Weimer Run watershed (373 ha), located near Davis, West Virginia, for three growing seasons with varying precipitation (2010 – 1042 mm; 2011 – 1739 mm; 2012 – 1244 mm; precipitation data from BDKW2 station, MesoWest, University of Utah). An apparent soil temperature threshold of 11 °C at 12 cm depth on FSOIL was observed in our data – where FSOIL rates greatly increase in variance above this threshold. For analysis, FSOIL values above this threshold were isolated and examined. Differences in FSOIL among years were apparent by elevation (F4,633 = 3.17; p = 0.013) and by vegetation cover (F4, 633 = 2.96; p = 0.019). For the Weimer Run watershed, vegetation exerts the major control on soil CO2 efflux (FSOIL), with the plots beneath shrubs at all elevations for all years showing the greatest mean rates of FSOIL (6.07 μmol CO2 m-2 s-1) compared to plots beneath closed-forest canopy (4.69 μmol CO2 m-2 s-1) and plots located in open, forest gaps (4.09 μmol CO2 m-2 s-1) plots. During periods of high soil moisture, we find that CO2 efflux rates are constrained and that maximum efflux rates in this system occur during periods of average to below average soil water availability. These findings offer valuable insight into the processes occurring within these topographically complex, temperate and humid systems, and the interactions of abiotic and biotic factors mediating biogeochemical cycles. With possible changing rainfall patterns as predicted by climate models, it is important to understand the couplings between water and carbon cycling at the watershed and landscape scales, and their potential dynamics under global change scenarios.

scholarly journals Soil CO<sub>2</sub> efflux in an old-growth southern conifer forests (<i>Agathis australis</i>) – magnitude, components, and controls

2016 ◽  
Author(s):  
Luitgard Schwendenmann ◽  
Cate Macinnis-Ng
Keyword(s):  
Regression Analysis ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Biomass ◽  
Soil Co2 Efflux ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Total Soil

Abstract. Total soil CO2 efflux and its component fluxes, autotrophic and heterotrophic respiration, were measured in a native forest in northern Aotearoa-New Zealand. The forest is dominated by Agathis australis (kauri) and is on an acidic, clay rich soil. Soil CO2 efflux, volumentric soil water content and soil temperature were measured bi-weekly to monthly at 42 locations over 18 months. Trenching and regression analysis was used to partition the total soil CO2 efflux. The effect of tree structure was investigated by calculating an index of local contribution (Ic, based on tree size and distance to the measurement location) followed by correlation analysis between Ic and soil CO2 efflux, root biomass, litterfall and soil characteristics. The mean total soil CO2 efflux was 3.47 μmol m−2 s−1. Using uni- and bivariate models showed that soil temperature (< 40 %) and volumetric soil water content (< 20 %) were poor predictors of the temporal variation in total soil CO2 efflux. In contrast, a stronger temperature sensitivity (around 57 %) was found for heterotrophic respiration. Autotrophic respiration accounted for 25 (trenching) or 28 % (regression analysis) of total soil CO2 efflux. We found significant positive relationships between kauri tree size distribution (Ic) and soil CO2 efflux, root biomass and mineral soil CN ratio within 5–6 m of the measurement points. Using multiple regression analysis revealed that 97 % of the spatial variability in soil CO2 efflux in this kauri dominated stand was explained by root biomass and soil temperature. Our findings highlight the need to consider tree species effects and spatial patterns in soil carbon related studies.

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