13C-14C relations reveal that soil 13C-depth gradient is linked to historical changes in vegetation 13C

Paul, Alexia; Balesdent, Jérôme; Hatté, Christine

doi:10.1007/s11104-019-04384-4

Cited by 15 publications

(6 citation statements)

References 59 publications

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“…Changes in the diversity, composition, and abundance of bacterial and fungal communities with depth were quantified using 16S rRNA/ITS amplicon sequencing and quantitative real-time PCR (qPCR). To investigate changes in C cycling dynamics down each soil core, measurements of soil isotopic composition ( 13 C / 12 C ratio) were performed, with the 13 C / 12 C ratio of soils previously having been used as a proxy for soil C turnover (Garten et al, 2008;Paul et al, 2020;Poage and Feng, 2004;Wang et al, 2018). Radiocarbon ageing based on measurements of 14 C abundance was further used to identify older stabilised C stocks (Chabbi et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Byers

Garrett

Armstrong

et al. 2023

SOIL

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Abstract. Forest soils are fundamental in regulating the global carbon (C) cycle; their capacity to accumulate large stores of C means they form a vital role in mitigating the effects of climate change. Understanding the processes that regulate forest soil C dynamics and stabilisation is important to maximise the capacity and longevity of C sequestration. Compared with surface soil layers, little is known about soil C dynamics in subsoil layers, sensu those below 30 cm depth. This knowledge gap creates large uncertainties when estimating the distribution of global soil C stocks and assessing the vulnerability of soil C reserves to climate change. This study aimed to dive deep into the subsoils of Puruki Experimental Forest (New Zealand) and characterise the changes in soil C dynamics and the soil microbiome down to 1 m soil depth. ITS and 16S rRNA sequencing and quantitative real-time PCR were used to measure changes in soil microbial diversity, composition, and abundance. Stable (δ13C) and radioactive (14C) C analyses were performed to assess depth-driven changes in the stability and age of soil C. Our research identified large declines in microbial diversity and abundance with soil depth, alongside significant structural shifts in community membership. Importantly, we conservatively estimate that more than 35 % of soil C stocks are present in subsoil layers below 30 cm. Although the age of soil C steadily increased with depth, reaching a mean radiocarbon age of 1571 yr BP (years before present) in the deepest soil layers, the stability of soil C varied between different subsoil depth increments. These research findings highlight the importance of quantifying subsoil C stocks for accurate C accounting. By performing a broad range of analytical measures, this research has comprehensively characterised the abiotic and biotic properties of a subsoil environment – a frequently understudied but significant component of forest ecosystems.

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Section: Introductionmentioning

confidence: 99%

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Byers

Garrett

Armstrong

et al. 2023

SOIL

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“…The organic carbon present in soil under a particular vegetation type has similar or slightly enriched δ 13 C values (Laskar et al 2010, 2013, 2016). The enrichment is due to incorporation of 13 C depleted CO 2 in the atmosphere during the industrial era (Suess Effect) (McCarrol and Loader 2004; Paul et al 2020) and preferential removal of lighter carbon during decomposition by microbes (Laskar et al 2016). Soil CO 2 has a δ 13 C value controlled by the decomposition of organic matter, root respiration and diffusive fractionation.…”

Section: Methodsmentioning

confidence: 99%

Estimation of Groundwater Residence Time Using Radiocarbon and Stable Isotope Ratio in Dissolved Inorganic Carbon and Soil CO₂

Agrawal,

Mohanty,

Rathi

et al. 2024

Radiocarbon

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Estimation of residence time of groundwater, particularly in regions with inadequate surface waters are very important for formulating sustainable groundwater management policies. We developed a technique for extracting dissolved inorganic carbon (DIC) quantitatively from water for measuring its 14C contents and presented the analytical details here. We also measured stable carbon isotope ratio (δ13C) in soil CO2 and groundwater DIC to correct the groundwater 14C ages. In addition, 14C in soil CO2 were measured for making necessary correction in the initial activity of the recharging water. The corrected 14C contents in the groundwater samples were used to estimate their residence times employing Lumped Parameter Models (LPM), a set of mathematical models to account for the processes that take place during transport from the recharge to the sampling spots. We present a case study focused on the calculation of radiocarbon ages and residence times for a groundwater sample collected from the campus of Physical Research Laboratory in Ahmedabad, Gujarat, India. The study also includes estimations of groundwater residence times using previously measured 14C ages of groundwater samples from Gujarat, India. Various factors controlling the groundwater ages in the LPM and their applicability are discussed.

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“…The simultaneous increases in the C/N ratios and δ 13 C values with depth were against commonly observed patterns in terrestrial soils and not straightforward to interpret. In terrestrial soils under C3 plants, C/N ratios generally decrease while δ 13 C values increase with depth, resulting in a negative correlation between them (Lorenz et al, 2020;Paul et al, 2020;Sollins et al, 2009;Werth and Kuzyakov, 2010). However, there are also cases where the carbon-stable isotope ratio decreases with decomposition (Lehmann et al, 2002).…”

Section: Organic Matter Early Diagenesis Inferred From C/n Ratios And...mentioning

confidence: 99%

“…Among these, only the increased relative dominance of roots compared to leaves could explain the simultaneous increases in the C/N ratios and δ 13 C values with depth, although all processes are not mutually exclusive (Table 3). Historical changes in vegetation 13 C abundance as a result of changes in atmospheric 13 C abundance ( 13 C-Suess effect) (Francey et al, 1999) and/or greater isotopic discrimination during photosynthesis under higher CO2 levels (Paul et al, 2020) could also explain the increase in δ 13 C values with depth (Fig. 5b), but they do not themselves provide an explanation for the increase in C/N ratios (Fig.…”

Section: Organic Matter Early Diagenesis Inferred From C/n Ratios And...mentioning

confidence: 99%

Functional organic matter components in mangrove soils revealed by density fractionation

Hamada¹,

Ohtsuka²,

Fujitake³

et al. 2023

Preprint

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The mechanisms underlying stabilization of soil organic matter (SOM) in coastal ecosystems, including mangrove forests, are poorly understood, limiting our ability to predict the consequences of disturbances. Here, we introduce density fractionation to mangrove soils to identify the distribution and properties of the functional components of SOM with regard to degradation state, stability, and origin, namely, the high-density fraction (HF), free low-density fraction (f-LF), and mineral-associated LF (m-LF). Three soil cores (1 m) were collected in a mangrove forest on Ishigaki Island, Japan and cut into 10 cm intervals and analyzed. The massive production of mangrove fine roots resulted in a high abundance of LFs throughout the cores, which markedly differed from terrestrial soils. Relative abundance of LFs together accounted for 38%–66% of total soil C. The m-LF was as abundant as f-LF and 1.6 times higher in relative abundance than the global average of terrestrial soils. The C/N ratios and δ13C values clearly increased with depth in all fractions, which was attributed to the increased contribution from roots. We found a consistent pattern in Δ14C values of density fractions. HF was the oldest with Δ14C between -149‰ and -97‰ followed by m-LF (between -130‰ and -87‰) and then f-LF (between -89‰ and 78‰), suggesting that mineral association may be pivotal in long-term carbon storage in the mangrove mineral soil. Our analysis successfully identified meaningful functional components of mangrove SOM, yet several questions remained unanswered, including a large variability in Δ14C in different cores. Future studies would benefit from a coupled analysis of quantity and quality of density fractions and geochemical factors in the mangrove soil.

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13C-14C relations reveal that soil 13C-depth gradient is linked to historical changes in vegetation 13C

Cited by 15 publications

References 59 publications

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Estimation of Groundwater Residence Time Using Radiocarbon and Stable Isotope Ratio in Dissolved Inorganic Carbon and Soil CO₂

Functional organic matter components in mangrove soils revealed by density fractionation

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13C-14C relations reveal that soil 13C-depth gradient is linked to historical changes in vegetation 13C

Cited by 15 publications

References 59 publications

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Soil depth as a driver of microbial and carbon dynamics in a planted forest (Pinus radiata) pumice soil

Estimation of Groundwater Residence Time Using Radiocarbon and Stable Isotope Ratio in Dissolved Inorganic Carbon and Soil CO2

Functional organic matter components in mangrove soils revealed by density fractionation

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Estimation of Groundwater Residence Time Using Radiocarbon and Stable Isotope Ratio in Dissolved Inorganic Carbon and Soil CO₂