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Based on the whole life cycle theory, the carbon effect of three different sizes of high-standard basic farmland construction projects is measured and analysed. The results show that the carbon emissions generated during the construction of high-standard basic farmland projects and the carbon absorption capacity at the later stage are different for projects of different sizes. The carbon emissions of different scales of high-standard basic farmland projects will increase during the construction stage. The results of carbon effect changes in the later operation and management stage show that the high-standard basic farmland construction projects will help reduce the carbon emissions of the field ecosystem where the farmland is located and increase its carbon sink capacity after the completion of construction, which is more obvious in larger projects. The emission reduction and carbon sequestration capacity of the farmland after remediation are improved to different degrees, which is more conducive to the ecological development of agricultural production and ecological environmental protection in the relevant areas. The study contributes to the green development of farmland, which is of some significance for the sustainable development of agriculture in Tianjin and the whole country. [ABSTRACT FROM AUTHOR]

Ecological security pattern is a critical way to ensuring urban ecological security and achieving sustainable urban development. It is also one of the most active study topics in the field of landscape ecology research. The scientific identification of ecological source areas has always been the technical difficulty and primary link in the construction of ecological security patterns. Therefore, based on the relevant theories of geography and landscape ecology, this paper selected Tianjin, China, as the research area to comprehensively identify the source area of ecological security patterns from the aspects of ecological function and landscape level. Firstly, the pressure-state-response model was used to evaluate the ecological environment quality under the influence of social-economic-natural factors from three aspects of pressure, state, and response. Secondly, the ecological structure was evaluated by combining morphological spatial pattern analysis and landscape connectivity index. Finally, the identified ecological source areas were verified by overlaying ecological control lines and calculating the coupling degree of socio-economic systems. The results revealed that (1) the total area of ecological sources identified by the PSR model in 2000, 2010, and 2020 accounted for 18.88%, 16.08%, and 15.28% of the total area, respectively. After the structural integrity assessment of MSPA and landscape connectivity, the area of ecological source in 2020 was less than that in 2010. It demonstrated that while considerable progress had been made in the restoration of the ecological environment in recent years, the connectivity between sources remained low. (2) The main landscape components of ecological source areas were woodlands and wetlands with high ecosystem service values, mainly located in the northern part of Jizhou District, most areas of Binhai New Area, southern Ninghe District, eastern Wuqing District, and northeastern Jinghai District. (3) There was a high degree of consistency between identified ecological source areas and ecological control lines. It was verified that the existing basic ecological control line policy is capable of protecting the most important patches. For the important patches falling outside the control line, the ecological protection red line preselected area can be considered. (4) Combined with the results of social-ecological coupling degree and source area change trend, the scientificity and rationality of ecological source identification method based on the PSR model and structural integrity were verified. The research results can provide theoretical references for the future urban planning and ecological protection of the study area, and also provide new ideas and case references for the source identification of ecological security pattern. [ABSTRACT FROM AUTHOR]

The evolution of land-use spatial conflict is a comprehensive reflection of regional development and a common phenomenon in urbanization. The research on land-use spatial conflicts can provide theoretical basis and practical support for spatial control. The present study employs Tianjin as the research object, and ecological risk assessment model was improved based on landscape pattern analysis by selecting appropriate indicators that may bring conflict risk problems. The spatial conflict measurement model of land-use based on the coordination of human-land-landscape elements was preliminarily constructed. The spatial and temporal evolution of land-use spatial conflict degree, and spatial autocorrelation from 2000 to 2020 was preliminarily analyzed. Results showed that (1) the conflict measurement level of the model was verified by Google Earth remote sensing image platform and field survey, and the results were relatively consistent with the actual situation, which proves that this method was feasible. (2) The areas with low intensity of land-use conflict were mainly distributed in remote mountainous areas with less human activities, while the areas with high comprehensive conflict index were mainly distributed in the central urban area with more active human activities and urbanization, the urban fringe area, the water-land ecotone, and some landscape transition areas. (3) There was a close relationship between land use spatial conflict and land-use change. Areas with severe and frequent land-use changes were often areas with noticeable land-use conflict changes. In the period of high land-use change intensity and frequent land-use mode conversion, it was also a period of a large area where regional land-use conflict was enhanced. (4) The overall level of conflict showed an average trend year by year, and the high conflict fluctuates greatly with first rising and then falling, but the change range was small. Moderate conflict mainly showed a decreasing trend, with an extensive change range. The early stage of the mild conflict was relatively stable, and the later stage changed significantly. [ABSTRACT FROM AUTHOR]

Underground coal mining leads to land subsidence, and the situation is particularly serious in the Coal-Grain Complex in eastern China, causing the crop production to be reduced or to be taken out. Backfilling with Yellow River sediment is one of the effective methods to solve the land subsidence in this area, but a key issue is how to select the optimal soil reconstruction profile so that the crop yield after backfilling and reclamation is unaffected. The main purpose of this study is to verify the feasibility of selecting the optimal soil reconstruction profile by rapid monitoring of crop growth and judging soil quality with the aid of unmanned aerial vehicle systems (UAVs). A control treatment and 13 experimental treatments were established for the study area. The control treatment consisted of using 30 cm topsoil and 90 cm subsoil and the topsoil is a proxy for native (undisturbed) soil from the study sites. All other treatments consisted of using varying combinations of subsoil and sediment overlain by 30 cm of topsoil. The vegetation indices from the UAV multispectral images, and the plant height and vegetation coverage from the UAV RGB images were used for estimation of the winter wheat biomass in a random forest regression. The results showed that the random forest regression model yielded accurate estimation of the aboveground biomass. Furthermore, knowledge of plant height and vegetation coverage improved the accuracy of prediction such that crop growth was well characterized. The optimal soil profile consisted of 0.3 m topsoil + 0.2 m subsoil + 0.2 m sediment + 0.2 m subsoil + 0.3 m sediment. A fast and effective airborne monitoring method for soil quality was established, thus providing greatly improved monitoring efficiency. [ABSTRACT FROM AUTHOR]