295 research outputs found
Belowground allocation and fate of tree assimilates in plant–soil–microorganisms system: 13C labeling and tracing under field conditions
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Extracellular enzyme activity and stoichiometry: The effect of soil microbial element limitation during leaf litter decomposition
No full textIncreasing contribution of microbial residues to soil organic carbon in grassland restoration chronosequence
No full texthttp://dx.doi.org/10.13039/501100012659 Foundation for Innovative Research Groups of the National Natural Science Foundation of Chin
Soil aggregation, aggregate stability, organic carbon and nitrogen in different soil aggregate fractions under forest and shrub vegetation on the Loess Plateau, China
No full textRevegetation has been reported as one of the most effective counter measures to reduce soil and water erosion on the Loess plateau in China. Soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions would be affected by different plant communities. The objectives of this study were to elucidate the effects of different plant communities on soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions in order to prove that the different plant covers enhance soil aggregate stability. Six kinds of soil samples under forest (Quercus liaotungensis, Populus davidiana, Pinus tabulaeformis, Bothriochloa, a 14 year abandoned land, and a 19 year bare fallow soil. Four kinds of soil samples under shrub land (the 24 year old Caragana Korshinskii Kom.; the 14 year old C Korshinskii Kom., 3 year old abandoned grazing land and traditional slope cropland which is claimed by the farmers for production with very low fertilizers) were collected from the hilly-gully area on the Loess Plateau, which was divided into 0-10 cm and 10-20 cm. We investigated soil aggregate stability and soil aggregate fractions by ultrasonic fractionation (USAS), and the distribution of organic carbon and nitrogen in different fractions under forest and afforested land, as key indicators for soil remediation through revegetation. The results showed that soil organic carbon (Corg) and total nitrogen (Nt) were strongly increased under forest and artificial shrub land compared to cropland and bare fallow land and were higher in the surface layers (0-10 cm) than in the subsurface (10-20 cm). Soil aggregate stability (SAS) was quite low under bare fallow land and cropping land soils, in comparison with the 4 forest communities. The three main fractions of soil aggregates, obtained by ultrasonic fractionation, were <63 mu m, 63-100 mu m and 100-250 mu m, which represented approximately 60%, 10% and 10%, respectively. In all land uses, macro-aggregates, 1000630 mu m > 630-250 mu m had a higher Corg content than micro-aggregates, 250-100 mu m > 100-63 mu m >> 63 mu m. In comparison to cropland and bare fallow land, forest and artificial shrub can protect and enhance the Corg, Nt and soil aggregate stability. The higher C:N ratio of macro-aggregate fractions indicates a rapid turnover of soil organic carbon in the top soil of forest sites and even on bare fallow and crop land. The narrow range of C:N ratio in micro-aggregates indicates that soil organic carbon in micro-aggregates is more stable than that in the macro-aggregates. We concluded that revegetation of eroded soils accelerates soil remediation and rehabilitation. (C) 2010 Elsevier B.V. All rights reserved
Call for joint international actions to improve scientific understanding and address soil erosion and riverine sediment issues in mountainous regions
No full textLarge-scale ecosystem carbon stocks and their driving factors across Loess Plateau
No full textAbstract The large-scale vegetation restoration project on the Loess Plateau increased the ecosystem carbon (C) stocks and affected C budget in arid and semi-arid ecosystems. The specific details affecting the C stocks, their distribution, and dependence on land use and climate were never presented and generalized. We assessed the effects of climate factors and soil properties on ecosystem C stocks through field investigation across the Loess Plateau. The total C stocks in the four ecosystems: forestlands [0.36], shrublands [0.24], grasslands [1.18], and farmlands [1.05] was 2.84 Pg (1 Pg = 10 15 g), among which 30% were stored in topsoil (0–20 cm), 53% in above-ground biomass, and 17% in roots. The total ecosystem C density decreased according to the climate from the southeast (warm dry) to the northwest (cold moist) of the Loess Plateau. The ecosystem C density decreased with increasing temperature (from 5 to 15 °C), but increased with precipitation (from 200 to 700 mm). Variation partitioning analysis and structural equation models indicated that ecosystem C density was more explained by climate compared with soil properties. This supports the theory and empirical findings that large scale pattern of ecosystem C density is predominantly regulated by climate on the Loess Plateau. Our results highlight that grasslands are more predestined to store C compared with the other ecosystems, and the C stored in roots is substantial and should be considered when assessing C stocks and strongly contributes to soil organic matter formation. We suggest that investing in roots can be an effective strategy for meeting part of Loess Plateau C reduction goals to mitigate climate change, which is necessary for validating and parameterizing C models worldwide.the National Natural Sciences Foundation of China 501100001809Shanghai Jiao Tong University 50110000492
Effects of microbial groups on soil organic carbon accrual and mineralization during high- and low-quality litter decomposition
No full texthttp://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of Chinahttp://dx.doi.org/10.13039/501100002858 China Postdoctoral Science Foundatio
Metabolic pathways of CO2 fixing microorganisms determined C-fixation rates in grassland soils along the precipitation gradient
No full textCO2 fixing microorganisms (CFMs) play a crucial role in carbon (C) sequestration in vegetation restricted areas, e.g., under semiarid and arid conditions. The factors controlling the underlying pathways of the CO2 fixation by microorganisms living in soils remain unclear. Here, almost all genes responsible for the eight CO2 fixation pathways in semiarid soil CFMs communities were identified using metagenomic analysis: including the reductive citrate cycle (rTCA), dicarboxylate-hydroxybutyrate cycle (DC/4-HB), reductive pentose phosphate cycle (Calvin), 3-hydroxypropionate bicycle (3-HP), 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB), C4-dicarboxylic acid, CAM cycle, and reductive acetyl-CoA pathway (Wood-Ljungdahl pathway). By tracing the CO2 fixation flux via 13C labeling, it was shown that the CO2 fixation rates increased along the precipitation gradient. The rTCA and 3-HP pathways for CO2 fixing microorganisms were closely associated with 13C incorporation into the soil organic matter under high mean annual precipitation (MAP) (400–600 mm), whereas the Calvin cycle played a vital role in soils under low MAP (<400 mm) conditions. The abundance of the key genes within the C fixing pathways showed that the microbial C accumulation in soils was mainly influenced by the MAP. In semi-arid to semi-humid grassland soils, where CO2 fixation by CFMs provided about 8.1–27 mg C m−2 day−1 input into the ecosystem, we demonstrated that the rTCA, Calvin, and 3-HP cycle were vital to this essential pathway of C sequestration.http://dx.doi.org/10.13039/100014717 National Natural Science Foundation of China National Outstanding Youth Science Fund Projecthttp://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of Chinahttp://dx.doi.org/10.13039/501100018647 RUDN Universit
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