Soil Organic Carbon

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Now showing 1 - 5 of 8
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    The lower labile carbon of surface soils in Chinese semiarid areas
    (Taylor & Francis Group - Informa UK Limited, 2023-02-11) Zhang, Fan; Qi, Jiamin; Gui, Congwen; Zhang, Yilin; Wang, Zheng
    Hot water extractable organic carbon (HWOC), the labile carbon component, is often used to indicate soil organic carbon (SOC) dynamics. Nevertheless, few studies have been carried out in arid climate areas which affects our full understanding of HWOC. Here, we investigated the change in HWOC in the topsoil of different ecosystems in the southern part of the Loess Plateau in the semiarid region of China and compared it with that in other regions. The HWOC concentrations of the study area (0-10 cm) were 0.27 ± 0.12 g C kg−1 and 0.19 ± 0.04 g C kg−1 in the natural and agricultural systems respectively, and the HWOC proportions were 1.38 ± 0.38% and 2.18 ± 0.22%. The HWOC concentration and proportion in the study area were much lower than the reported data in other areas, which may be affected by drought conditions. Irrigation could weaken the difference in HWOC between agricultural systems in different regions. Since HWOC is easily lost due to the impact of the arid climate, the soil carbon balance and carbon sequestration in arid and semiarid areas are relatively unstable, indicating that soil management should be improved in combination with water management.
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    Soil carbon sequestration benefits of active versus natural restoration vary with initial carbon content and soil layer
    (Springer Nature, 2023-03-17) Tian, Dashaun; Xiang, Yangzhou; Seabloom, Eric; Wang, Jinsong; Jia, Xiaoxu; Li, Tingting; Li, Zhaolei; Yang, Jian; Guo, Hongbo; Niu, Shuli
    Reducing terrestrial carbon emissions is a big challenge for human societies. Ecosystem restoration is predominant to reverse land degradation and carbon loss. Though active restoration of croplands is assumed to increase carbon sequestration more than natural regeneration, it still lacks the robust paired comparisons between them. Here we performed a large-scale paired comparison of active versus natural restoration effects on soil carbon sequestration across China. We found that two restoration strategies consistently enhanced soil carbon relative to croplands, however, the benefits of active restoration versus natural regeneration were highly context-dependent. Active restoration only sequestered more carbon in carbon-poor soils but less carbon in carbon-rich soils than natural regeneration. Moreover, active restoration fixed greater carbon in topsoil but less carbon in subsoil. Overall, these findings highlight landscape context-dependent application of active restoration and natural regeneration, further guiding the efficient management of limited resources to maximize the restoration benefits of carbon sequestration.
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    Ecosystem productivity has a stronger influence than soil age on surface soil carbon storage across global biomes
    (Springer Nature, 2022-10-07) Plaza, César; García-Palacios, Pablo; Berhe, Asmeret Asmeret; Barquero, Jesús; Bastida, Felipe; Png, G. Kenny; Rey, Ana; Bardgett, Richard D.; Delgado-Baquerizo, Manuel
    Interactions between soil organic matter and minerals largely govern the carbon sequestration capacity of soils. Yet, variations in the proportions of free light (unprotected) and mineral-associated (protected) carbon as soil develops in contrasting ecosystems are poorly constrained. Here, we studied 16 long-term chronosequences from six continents and found that the ecosystem type is more important than soil age (centuries to millennia) in explaining the proportion of unprotected and mineral-associated carbon fractions in surface soils across global biomes. Soil carbon pools in highly productive tropical and temperate forests were dominated by the unprotected carbon fraction and were highly vulnerable to reductions in ecosystem productivity and warming. Conversely, soil carbon in low productivity, drier and colder ecosystems was dominated by mineral-protected carbon, and was less responsive to warming. Our findings emphasize the importance of conserving ecosystem productivity to protect carbon stored in surface soils.
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    Environmental and microbial controls on microbial necromass recycling, an important precursor for soil carbon stabilization
    (Springer Nature, 2020-10-22) Buckeridge, Kate M.; Mason, Kelly E.; McNamara, Niall P.; Ostle, Nick; Puissant, Jeremy; Goodall, Tim; Griffiths, Robert I.; Stott, Andrew W.; Whitaker, Jeanette
    There is an emerging consensus that microbial necromass carbon is the primary constituent of stable soil carbon, yet the controls on the stabilization process are unknown. Prior to stabilization, microbial necromass may be recycled by the microbial community. We propose that the efficiency of this recycling is a critical determinant of soil carbon stabilization rates. Here we explore the controls on necromass recycling efficiency in 27 UK grassland soils using stable isotope tracing and indicator species analysis. We found that recycling efficiency was unaffected by land management. Instead, recycling efficiency increased with microbial growth rate on necromass, and was highest in soils with low historical precipitation. We identified bacterial and fungal indicators of necromass recycling efficiency, which could be used to clarify soil carbon stabilization mechanisms. We conclude that environmental and microbial controls have a strong influence on necromass recycling, and suggest that this, in turn, influences soil carbon stabilization.
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    Response of soil respiration to changes in soil temperature and water table level in drained and restored peatlands of the southeastern United States
    (Springer Nature, 2022-11-19) Swails, E. E.; Ardón, M.; Krauss, K. W.; Peralta, A. L.; Emanual, R. E.; Helton, A. M.; Morse, J. L.; Gutenberg, L.; Cormier, N.; Shoch, D.; Settlemyer, S.; Soderholm, E.; Boutin, B. P.; Peoples, C.; Ward, S.
    Background: Extensive drainage of peatlands in the southeastern United States coastal plain for the purposes of agriculture and timber harvesting has led to large releases of soil carbon as carbon dioxide (CO2) due to enhanced peat decomposition. Growth in mechanisms that provide fnancial incentives for reducing emissions from land use and land-use change could increase funding for hydrological restoration that reduces peat CO2 emissions from these ecosystems. Measuring soil respiration and physical drivers across a range of site characteristics and land use histories is valuable for understanding how CO2 emissions from peat decomposition may respond to raising water table levels. We combined measurements of total soil respiration, depth to water table from soil surface, and soil temperature from drained and restored peatlands at three locations in eastern North Carolina and one location in southeastern Virginia to investigate relationships among total soil respiration and physical drivers, and to develop models relating total soil respiration to parameters that can be easily measured and monitored in the feld. Results: Total soil respiration increased with deeper water tables and warmer soil temperatures in both drained and hydrologically restored peatlands. Variation in soil respiration was more strongly linked to soil temperature at drained (R2=0.57, p<0.0001) than restored sites (R2=0.28, p<0.0001). Conclusions: The results suggest that drainage amplifes the impact of warming temperatures on peat decomposi tion. Proxy measurements for estimation of CO2 emissions from peat decomposition represent a considerable cost reduction compared to direct soil fux measurements for land managers contemplating the potential climate impact of restoring drained peatland sites. Research can help to increase understanding of factors infuencing variation in soil respiration in addition to physical variables such as depth to water table and soil temperature.