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Saline-alkali land is an important component of terrestrial ecosystems and may serve as a carbon sink but its net contribution to the overall terrestrial carbon sink is unknown. Using methods recommended by the IPCC, this study evaluates the impacts of interconverting saline-alkali and non-saline-alkali land on terrestrial carbon stocks by measuring two major carbon pools (soil organic carbon and vegetation carbon) in the saline-alkali land of China's Songnen Plain. Distinct phases in the evolution of the region's terrestrial carbon stock were delineated, factors contributing to transitions between phases were identified, and the effects of changes in the saline-alkali land carbon stock on the overall terrestrial carbon sink were estimated. Between 2005 and 2020, the region's saline-alkali land carbon stock initially increased, then declined, and finally increased again. However, the overall terrestrial carbon stock decreased by 0.5 Tg (1 Tg = 1012 g), indicating that the increase in the saline-alkali land carbon stock was due primarily to expansion of the saline-alkali land area. The conversion of non-saline-alkali land to saline-alkali land was a carbon-emitting process; consequently, in areas undergoing saline-alkali land change, the lower carbon density bound was equal to the carbon density of unconverted saline-alkali land and the upper bound was equal to the carbon density of unconverted non-saline-alkali land. In general, changes in the carbon stock of saline-alkali land correlated negatively with changes in the overall terrestrial carbon stock. The conversion of saline-alkali land into grassland and cropland through biochar improvement and the planting of saline-tolerant crops (Leymus chinensis, salt-tolerant rice) has a positive effect on promoting the enhancement of terrestrial carbon stocks. [ABSTRACT FROM AUTHOR]

Land-use change is an important factor affecting terrestrial carbon balance, and it is crucial to explore the response of terrestrial carbon stocks to land-use change, especially in the Songnen Plain, which faces a fierce conflict between the rapid growth of production activities and ecosystem degradation. In this study, we measured soil organic carbon and vegetation biocarbon stocks in the Songnen Plain based on IPCC-recommended methodologies, and explored the characteristics of carbon stock changes in land-use trajectories, land-use drivers, and specific land-use change scenarios (cropland cultivation, returning cropland to forests, the expansion of land for construction, deforestation, greening, and land degradation). The results showed that soil organic carbon stock in the Songnen Plain decreased by 1.63 × 105 t, and vegetation biocarbon stock increased by 2.10 × 107 t from 2005 to 2020. Human factors and natural factors jointly contributed to the land-use change, but the extent of the role of human factors was greater than that of natural factors. The increase in land-use trajectory led to the decrease in soil organic carbon stock and the increase in vegetation biocarbon stock. There was no difference in the effects of human-induced and natural-induced land-use changes on vegetation biocarbon stocks, but the effects on soil organic carbon stocks were diametrically opposite, increasing by 43.27 t/km2 and decreasing by 182.02 t/km2, respectively. The reclamation of arable land, returning cropland to forests, and greening led to a net increase in terrestrial carbon stocks (+813,291.84 t), whereas land degradation, deforestation, and land-use expansion led to a decrease in terrestrial carbon stocks (−460,710.2 t). The results of this study can provide a reference for the adjustment of land-use structure and the increase in terrestrial carbon stock in the Songnen Plain. [ABSTRACT FROM AUTHOR]

We assessed the effectiveness of land optimization for controlling non-point source (NPS) pollution by combining a multi-objective dynamic planning approach with the application of the Land Use and its Effects at Small regional extents model and the Soil and Water Assessment Tool. The combined modeling approach showed substantial ability to reduce NPS pollution in Shitoukoumen Reservoir, Changchun City, China, reducing the annual total loads of nitrogen and phosphorus in the study area by 8.7 and 10.12%, respectively. The total nitrogen load decreased significantly and stabilized at less than 8 kg/hm2 from a peak level of over 15 kg/hm2. Higher total phosphorus loads before land use optimization were concentrated in the central parts of the study area, with the highest values exceeding 2.3 kg/hm2, and tended to spread outward but resolved at 1.5 kg/hm2 after optimization. The results showed that from a macro-perspective, optimization of the spatial distribution and quantitative composition of land use can effectively control NPS pollution. The study also demonstrates the potential effectiveness of the coupled multi-model methodology for mitigating NPS in the future. [ABSTRACT FROM AUTHOR]

Soil erosion and surface pollution near reservoirs can adversely affect water quality and safety. Soil aggregate stability is an important predictor of soil water loss and erosion resistance that is strongly influenced by land use. This study therefore aimed to identify factors affecting soil aggregate stability near reservoirs to provide empirical and theoretical insights that could guide the development of management measures to increase land quality, optimize land use, and maximize sustainability. This study focuses on the land around the Shitoukoumen Reservoir in China and examines the effects of six land use types, eleven soil physicochemical properties, and five environmental factors. Ninety-four sets of soil samples were collected in 2021 for analysis of soil aggregates and properties. Particle size classification of soil aggregates was carried out using the wet sieve method and four indicators were calculated to evaluate the effects of land use, soil physicochemical properties, and environmental factors on soil aggregate stability: water stable aggregates (WSA), mean weight diameter (MWD), geometric mean diameter (GMD), and fractal dimension (D). Descriptive statistics and geostatistics were used to explore the spatial distributions of soil aggregate stability around the reservoir and the influence of soil properties was studied using correlation analysis and path analysis. The conclusion indicates that land use type significantly affects aggregate stability. The most stable aggregates were found in paddy fields (WSA = 0.77, MWD = 0.76, GMD = 0.57) and forests (WSA = 0.75, MWD = 0.76, GMD = 0.55), followed by an orchard, irrigated land, and grassland. Aggregate stability was worst in upland sites (WSA = 0.61, D = 2.28), where soil aggregates were highly fragmented. There were clear spatial correlations between all four stability indicators. The environmental factors and soil physicochemical characteristics with the strongest influence on aggregate stability were soil organic matter, pH, soil clay content, total nitrogen, and temperature changes. Path analysis revealed that some soil properties affect aggregate stability indirectly, with particularly complex relationships between clay, soil organic matter, and pH. In conclusion, land use type, soil organic matter, pH, soil clay content, total nitrogen, these soil physicochemical properties, and environmental factors, especially temperature, significantly affect soil aggregate stability around reservoirs. In the future, it is necessary to appropriately change upland into paddy land, increase forest land, and appropriately add organic fertilizer to improve soil quality. [ABSTRACT FROM AUTHOR]

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-9701.2008.01128.x Byline: Yuefen Li (1), Bin Zhang (2) Abstract: The segmentation of global manufacturing and services provided China and subsequently India with a golden opportunity to make full use of their absolute advantage - low-cost, yet educated labour - to integrate into the world economy within a comparatively shorter period of time than some earlier industrialisers. Though international trade functioned as a vent of surplus in view of the narrowness of their domestic markets at the beginning of their economic catch-up, the label of export-led model may not reflect the real picture as imports underwent dramatic increases during their respective growth periods, in particular for China. Foreign direct investment has played a pivotal role in their economic growth and has major presence in international trade and investment in leading sectors of both countries, giving rise to certain special features and weak links for their economic expansion and sustainability of fast economic growth. To maintain more broad-based, fast and balanced growth, it seems that both countries have to redress sectoral imbalances, encourage technology upgrading and cope with future changes in demographic profiles which constituted a trigger to fast economic growth at the time of their respective economic reform. Author Affiliation: (1)UNCTAD, Geneva, and (2)Chinese Academy of Social Sciences, Beijing

Nitrous oxide (N2O) is an important greenhouse gas that plays a significant role in atmospheric photochemical reactions and contributes to stratospheric ozone depletion. Soils are the main sources of N2O emissions. In recent years, it has been demonstrated that soil is not only a source but also a sink of N2O uptake and consumption. N2O emissions at the soil surface are the result of gross N2O production, uptake, and consumption, which are co-occurring processes. Soil N2O uptake and consumption are complex biological processes, and their mechanisms are still worth an in-depth systematic study. This paper aimed to systematically address the current research progress on soil N2O uptake and consumption. Based on a bibliometric perspective, this study has highlighted the pathways of soil N2O uptake and consumption and their driving factors and measurement techniques. This systematic review of N2O uptake and consumption will help to further understand N transformations and soil N2O emissions. [ABSTRACT FROM AUTHOR]