Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau
<p>Microbial release of CO<span class="inline-formula"><sub>2</sub></span> from soils to the atmosphere reflects how environmental conditions affect the stability of soil organic matter (SOM), especially in massive organic-rich ecosystems like the peatlands an...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-03-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/21/1277/2024/bg-21-1277-2024.pdf |
| _version_ | 1797258419843891200 |
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| author | A. Tangarife-Escobar G. Guggenberger X. Feng G. Dai C. Urbina-Malo M. Azizi-Rad C. A. Sierra C. A. Sierra |
| author_facet | A. Tangarife-Escobar G. Guggenberger X. Feng G. Dai C. Urbina-Malo M. Azizi-Rad C. A. Sierra C. A. Sierra |
| author_sort | A. Tangarife-Escobar |
| collection | DOAJ |
| description | <p>Microbial release of CO<span class="inline-formula"><sub>2</sub></span> from soils to the atmosphere reflects how environmental conditions affect the stability of soil organic matter (SOM), especially in massive organic-rich ecosystems like the peatlands and grasslands of the Qinghai–Tibetan Plateau (QTP). Radiocarbon (<span class="inline-formula"><sup>14</sup></span>C) is an important tracer of the global carbon cycle and can be used to understand SOM dynamics through the estimation of time lags between carbon fixation and respiration, often assessed with metrics such as age and transit time. In this study, we incubated peatland and grassland soils at four temperature (5, 10, 15 and 20 °C) and two water-filled pore space (WFPS) levels (60 % and 95 %) and measured the <span class="inline-formula"><sup>14</sup></span>C signature of bulk soil and heterotrophic respired CO<span class="inline-formula"><sub>2</sub></span>. We compared the relation between the <span class="inline-formula">Δ<sup>14</sup></span>C of the bulk soil and the <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> of respired carbon as a function of temperature and WFPS for the two soils. To better interpret our results, we used a mathematical model to analyse how the calculated number of pools, decomposition rates of carbon (<span class="inline-formula"><i>k</i></span>), transfer (<span class="inline-formula"><i>α</i></span>) and partitioning (<span class="inline-formula"><i>γ</i></span>) coefficients affect the <span class="inline-formula">Δ<sup>14</sup></span>C bulk and <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> relation, with their respective mean age and mean transit time. From our incubations, we found that <span class="inline-formula"><sup>14</sup></span>C values in bulk and CO<span class="inline-formula"><sub>2</sub></span> from peatland were significantly more depleted (old) than from grassland soil. Our results showed that changes in temperature did not affect the <span class="inline-formula">Δ<sup>14</sup></span>C values of heterotrophic respired CO<span class="inline-formula"><sub>2</sub></span> in either soil. However, changes in WFPS had a small effect on the <span class="inline-formula"><sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> in grassland soils and a significant influence in peatland soils, where higher WFPS levels led to more depleted <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span>. In our models, the correspondence between <span class="inline-formula">Δ<sup>14</sup></span>C, age and transit time highly depended on the internal dynamics of the soil (<span class="inline-formula"><i>k</i></span>, <span class="inline-formula"><i>α</i></span>, <span class="inline-formula"><i>γ</i></span> and number of pools) as well as on model structure. We observed large differences between slow and fast cycling systems, where low values of decomposition rates modified the <span class="inline-formula">Δ<sup>14</sup></span>C values in a non-linear pattern due to the incorporation of modern carbon (<span class="inline-formula"><sup>14</sup></span>C bomb) in the soil. We concluded that the stability of carbon in the peatland and grassland soils of the QTP depends strongly on the direction of change in moisture and how it affects the rates of SOM decomposition, while temperature regulates the number of fluxes. Current land cover modification (desiccation) in Zoigê peatlands and climate change occurring on the QTP might largely increase CO<span class="inline-formula"><sub>2</sub></span> fluxes along with the release of old carbon to the atmosphere potentially shifting carbon sinks into sources.</p> |
| first_indexed | 2024-04-24T22:53:14Z |
| format | Article |
| id | doaj.art-1116b311ec0543779d9d4f70a8c655d0 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-24T22:53:14Z |
| publishDate | 2024-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-1116b311ec0543779d9d4f70a8c655d02024-03-18T09:04:09ZengCopernicus PublicationsBiogeosciences1726-41701726-41892024-03-01211277129910.5194/bg-21-1277-2024Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan PlateauA. Tangarife-Escobar0G. Guggenberger1X. Feng2G. Dai3C. Urbina-Malo4M. Azizi-Rad5C. A. Sierra6C. A. Sierra7Max Planck Institute for Biogeochemistry, Jena, GermanyInstitute of Soil Science, Leibniz Universität Hannover, Hanover, GermanyInstitute of Botany, Chinese Academy of Sciences, Beijing, ChinaInstitute of Botany, Chinese Academy of Sciences, Beijing, ChinaInstitute of Soil Science, Leibniz Universität Hannover, Hanover, GermanyMax Planck Institute for Biogeochemistry, Jena, GermanyMax Planck Institute for Biogeochemistry, Jena, GermanyDepartment of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden<p>Microbial release of CO<span class="inline-formula"><sub>2</sub></span> from soils to the atmosphere reflects how environmental conditions affect the stability of soil organic matter (SOM), especially in massive organic-rich ecosystems like the peatlands and grasslands of the Qinghai–Tibetan Plateau (QTP). Radiocarbon (<span class="inline-formula"><sup>14</sup></span>C) is an important tracer of the global carbon cycle and can be used to understand SOM dynamics through the estimation of time lags between carbon fixation and respiration, often assessed with metrics such as age and transit time. In this study, we incubated peatland and grassland soils at four temperature (5, 10, 15 and 20 °C) and two water-filled pore space (WFPS) levels (60 % and 95 %) and measured the <span class="inline-formula"><sup>14</sup></span>C signature of bulk soil and heterotrophic respired CO<span class="inline-formula"><sub>2</sub></span>. We compared the relation between the <span class="inline-formula">Δ<sup>14</sup></span>C of the bulk soil and the <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> of respired carbon as a function of temperature and WFPS for the two soils. To better interpret our results, we used a mathematical model to analyse how the calculated number of pools, decomposition rates of carbon (<span class="inline-formula"><i>k</i></span>), transfer (<span class="inline-formula"><i>α</i></span>) and partitioning (<span class="inline-formula"><i>γ</i></span>) coefficients affect the <span class="inline-formula">Δ<sup>14</sup></span>C bulk and <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> relation, with their respective mean age and mean transit time. From our incubations, we found that <span class="inline-formula"><sup>14</sup></span>C values in bulk and CO<span class="inline-formula"><sub>2</sub></span> from peatland were significantly more depleted (old) than from grassland soil. Our results showed that changes in temperature did not affect the <span class="inline-formula">Δ<sup>14</sup></span>C values of heterotrophic respired CO<span class="inline-formula"><sub>2</sub></span> in either soil. However, changes in WFPS had a small effect on the <span class="inline-formula"><sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span> in grassland soils and a significant influence in peatland soils, where higher WFPS levels led to more depleted <span class="inline-formula">Δ<sup>14</sup></span>CO<span class="inline-formula"><sub>2</sub></span>. In our models, the correspondence between <span class="inline-formula">Δ<sup>14</sup></span>C, age and transit time highly depended on the internal dynamics of the soil (<span class="inline-formula"><i>k</i></span>, <span class="inline-formula"><i>α</i></span>, <span class="inline-formula"><i>γ</i></span> and number of pools) as well as on model structure. We observed large differences between slow and fast cycling systems, where low values of decomposition rates modified the <span class="inline-formula">Δ<sup>14</sup></span>C values in a non-linear pattern due to the incorporation of modern carbon (<span class="inline-formula"><sup>14</sup></span>C bomb) in the soil. We concluded that the stability of carbon in the peatland and grassland soils of the QTP depends strongly on the direction of change in moisture and how it affects the rates of SOM decomposition, while temperature regulates the number of fluxes. Current land cover modification (desiccation) in Zoigê peatlands and climate change occurring on the QTP might largely increase CO<span class="inline-formula"><sub>2</sub></span> fluxes along with the release of old carbon to the atmosphere potentially shifting carbon sinks into sources.</p>https://bg.copernicus.org/articles/21/1277/2024/bg-21-1277-2024.pdf |
| spellingShingle | A. Tangarife-Escobar G. Guggenberger X. Feng G. Dai C. Urbina-Malo M. Azizi-Rad C. A. Sierra C. A. Sierra Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau Biogeosciences |
| title | Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau |
| title_full | Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau |
| title_fullStr | Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau |
| title_full_unstemmed | Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau |
| title_short | Moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the Tibetan Plateau |
| title_sort | moisture and temperature effects on the radiocarbon signature of respired carbon dioxide to assess stability of soil carbon in the tibetan plateau |
| url | https://bg.copernicus.org/articles/21/1277/2024/bg-21-1277-2024.pdf |
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