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Beijing–Tianjin–Hebei, the main economic area in northern China, has seen significant changes in its regional economic and physical landscape as a result of the coordinated development strategy. Assessing the link between land use and land cover (LULC) change and carbon emissions in the Chaobai River region, which represents the growth of the Beijing–Tianjin–Hebei urban agglomeration, is crucial to achieve coordinated low-carbon development in this area. This study uses statistics from statistical yearbooks of Chinese provinces and cities along with land use change data to analyze the relationship between land use changes and carbon emissions in the Chaobai River region from 2001 to 2017 using dynamic land use attitudes and land use transfer matrices, combined with carbon emission factors based on the IPCC inventory method and carbon emission models for energy consumption. In addition, this study makes use of the LMDI model and geographical detectors to identify and assess the factors that influence changes in land use carbon emissions and the driving forces behind the regional differentiation of land use changes. The results show that: (1) The Chaobai River region's predominant land use classes during the past 17 years have been agricultural land and construction land. In addition to the decrease in cropland and the increase in urban land, the land use patterns of other land classes also changed to a certain extent. (2) Carbon emissions from land use showed an increasing trend, from 6.1 × 106 tons in 2001 to 1.1 × 107 tons in 2017. (3) Carbon emission intensity, economic development level, land use efficiency, and construction land scale have a certain regularity in the evolution of carbon emissions, and economic development level has become the most important driving factor controlling the growth of land use carbon emissions. (4) Driving factors in different periods have different degrees of influence on land use change, among which socio-economic factors such as population density and GDP have the strongest explanatory power. In addition, the interactions of each factor mainly present a double factor enhancement. In the future, the Chaobai River region should be based on the coordinated development strategy and take the "double carbon" target as its guiding principle to promote the innovation of the regional development system and further achieve the optimization of the regional land use patterns. [ABSTRACT FROM AUTHOR]

Considering the significant influence of mercury (Hg) contamination on the land reclamation inopencast coalmine, the spatial distribution patterns and ecological risks of Hg were investigated and the regulating factors of Hg mobility were determined in the South Dump of the Pingshuo opencast coalmine. The results show that the total Hg (HgT) contents of most soil samples (83.7%) vary from 6 to 50 μg kg−1, while the potential ecological risk index (EIHg) values of most samples (79.8%) are lower than 80, indicating that most reclaimed soils are in relatively good conditions and the soil samples at high to very high ecological risk are mainly collected near the backfilled coal gangue. Moreover, the kriging maps of the geo-accumulation index (Igeo) indicate that the uncontaminated areas (Igeo < 0) and Hg-contaminated areas (Igeo > 0) in topsoil (0–10 cm) are roughly divided by an "east–west arc" while the Hg-contaminated areas in other soil horizons are characterized by a "point distribution pattern". The slight Hg contamination in topsoil is mainly triggered by the atmospheric Hg deposition from the nearby coal-fired power plant, while the Hg contamination in other soil horizons should be attributed to the weathering and spontaneous combustion of coal gangue. On the other hand, Pearson's correlation analyses show that HgT contents were positively correlated with clay (r = 0.31, P < 0.01) and SOC (r = 0.53, P < 0.01) contents. This study can provide some insight for the land reclamation measures in the opencast coalmine. [ABSTRACT FROM AUTHOR]

To reveal the variability of different reconstructed soil ratios and different vegetation growth grades on the water holding capacity of recon-structed soil, the most suitable ratio of reconstructed soil materials was explored. Taking the inner dump of Shengli mining area in Inner Mongolia of China as the research area, the reconstructed soil of reclaimed land was investigated and sampled. One-way analysis of variance was used to analyze the difference of the moisture content of the reconstructed soil, and the reasons for the difference were discussed. The results showed that: (1) Among the different soil reconstructions, soil moisture content was higher when soil reconstructions were rock and soil stripping material: coal gangue: fly ash = 3:4:3. The soil moisture content of un-reclaimed land was mostly at a high level when the soil reconstruction method was rock and soil stripping material; and the soil moisture content was not at the highest level when the vegetation growth grade was higher. This indicates that it was not the case that the better the vegetation growth condition was, the higher the soil moisture content was. (2) In the case where the soil reconstruction method was rock and soil stripping material: coal gangue = 2:3, the soil moisture content of the reclaimed land decreased with the reduction of tillage frequency when the vegetation growth condition was optimal (vegetation growth grade was 4). (3) In the case where the soil reconstruction method was rock and soil stripping material: coal gangue: fly ash = 3:4:3, when the vegetation growth condition was better (vegetation growth grade was 3 and 4), the soil moisture content of the re-claimed land was highest when it was tilled once every 15 days. It was also found in combination with other soil reconstruction methods that it was not always the case that the higher the frequency of tillage, the higher the soil moisture content. The study of coal gangue, fly ash and rocky soil stripping as topsoil substitute materials with their different ratios on reconstructed soil provides support for the reclamation work in topsoil scarce mines and provides technical reference for the ecological restoration project of grassland open-pit mines in the same climate zone. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to analyze the interest conflicts and strategy evolution process of various stakeholders in the process of homestead withdrawal, to reveal which key factors can balance the interests of all parties. Design/methodology/approach: The authors developed an evolutionary game theoretical framework for homestead withdrawal in Yujiang District, Jiangxi Province, China. The authors compared the dynamic process of strategy change in different situations based on system dynamics. Findings: Compared with indirect external factors, direct economic factors, such as increasing compensation standards or increasing fines, are more likely to encourage peasants to withdraw from their homesteads. The dynamic subsidy strategy can increase the probability of peasants withdrawing from their homestead. Additionally, awarding officials with promotions can effectively encourage local governments during the process. Originality/value: Previous studies have conceptualized farmers' willingness to withdraw from their homestead as a static process, ignoring the underlying dynamism. This paper analyzes the game mechanism among the stakeholders of the homestead withdrawal process from a dynamic perspective, to provide efficient suggestions regarding policymaking for homestead withdrawal. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the soil substitutes in land reclamation following mining activities. This study revealed different reconstructed soil materials have different effects on the chemical properties of reconstructed soil and explored the appropriate proportions of reconstructed soil materials. Using topsoil, coal gangue, fly ash, and rock and soil stripping material from the Shengli Mining Area of Inner Mongolia in China as raw materials, potting experiments were carried out according to different proportions. The variance analysis method was used to analyze the difference in the soil pH values, soil organic matter (SOM) content, soil total nitrogen (STN) content, soil available phosphorus (SAP) content and soil available potassium (SAK) content of the reconstructed soil, and the reasons for the difference were discussed. The results showed that in the treatment group where the topsoil substitute material was coal gangue, when the coal gangue content was 30%, 40%, and 50%, the pH values of reconstructed soil were lower than that of the control scheme. When the coal gangue content exceeded 10%, the soil nutrient status was obviously improved. In the treatment group where the topsoil substitute material was fly ash, the chemical properties of reconstructed soil tended to deteriorate. In the treatment group where the topsoil substitute material was rock and soil stripping material, when the content of rock and soil stripping material exceeded 20%, the chemical properties of reconstructed soil were mostly better than those of the control scheme. The study of the different proportions of coal gangue, fly ash, and rock and soil stripping material as topsoil substitute materials provide support for reclamation work in mining areas where topsoil is scarce, as well as a reference for ecological restoration projects in grassland open-pit mining areas around the world. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study included the full life cycle of the coal-based areas' development. • Ecosystem service supply capacity was overall optimized but locally deteriorative. • Ecosystem service supply capacity shifted during the rapid-development period. • Natural environment and anthropogenic choices jointly drove ecosystem service. • Provided actionable strategies for high-quality development of coal-based areas. The game between socio-economic development and ecological development has always been the core issue in coal-based areas, and ecosystem services could unify the two into one framework. However, at present, the related research has made slow progress in ecosystem structure optimization and regional sustainable development. Pinglu, as a representative area of China's Reform and Opening Up and the first Sino-foreign joint venture open-pit coal mine, has fragile ecological characteristics and resource development attributes that are typical in related research at home and abroad. Therefore, this study took the typical coal-based town as an example and analyzed the ecosystem service situation with its driving mechanism relied on ArcGIS, InVEST and Geodetector tools to solve the contradiction between development and protection of such areas. The results revealed that: (1) The overall supply capacity of each ecosystem service in Pinglu during the 40-year period showed an improving trend, but there was also a deterioration of habitat quality and carbon sequestration services; (2) The ecosystem service provisioning capacity in Pinglu needed to be improved comprehensively, and the key areas for upgrading and improvement were southwestern townships; (3) The driving force for food supply and soil conservation changed from mainly environmental and socio-economic to environmental, the driving force for water production, habitat quality and wind-sand conservation mainly environmental and socio-economic, the land-use type was the complete driving factor for carbon sequestration. (4) The study area development successively experienced a slow-growth period, a rapid-growth period, a rapid-decline period and a stable-development period, and accordingly formed a labor-intensive economy, a resource-intensive economy, a structural-adjustment economy and a high-quality oriented economy. The study of ecosystem services and their driving mechanisms in coal-based towns could provide optimization strategies for the green and sustainable development of such regions. And this study could make up for the shortcomings of national ecological civilization construction and ecological protection in resource-based areas. [ABSTRACT FROM AUTHOR]

The mining and reclaiming techniques of open-pit coal mines will affect the physical properties of the soil and the growth of vegetation. The traditional method of obtaining soil physical properties is time-consuming and laborious, so developing a rapid and non-destructive method for detecting typical soil physical properties in mining areas is of great significance for reclamation work. To study the typical soil physical properties of the reclaimed land in the mining area, we took the dumping sites of the Antaibao Open-pit Mine of China Coal as the research object and obtained measured data through the Ground Penetrating Radar (GPR) detection method and the soil profile sampling method. Then, the image analysis method, statistical analysis method and comparative analysis method were used to analyze the spatial variability for the soil moisture content, the effective soil layer thickness and the soil gravel content in the reclamation area. The results support the following conclusions: (1) The typical soil physical properties, namely, the soil moisture content, the effective soil layer thickness and the soil gravel content, of the reclaimed land in the mining area vary spatially. (2) Locally strong and fluctuating strong reflections in the 3D GPR image indicate that the detected sample is partially rich in water, and the spatial variability in the sudden moisture content of the reclamation in the mining area can be analyzed. (3) A low-frequency signal with good continuity in the 3D GPR image indicates that there is soil stratification under the detected sample, and the depth of the low-frequency signal with good continuity in the 3D GPR image can be used to characterize the effective soil layer in the reclaimed area. (4) The soil gravel content of the reclaimed soil can be analyzed from the statistics of the number of isolated gravel signals in the 3D GPR image. The greater the number of isolated gravel signals is, the higher the soil gravel content is. These conclusions, from both horizontal and vertical perspectives, suggest that 3D GPR images can be used to determine the typical physical properties of soil in a reclaimed land. These results can provide technical support for the efficient reclamation of a mining area and related restoration work. [ABSTRACT FROM AUTHOR]

Changes in cultivated land in China are related to food security for nearly 1.4 billion people. Administrative ruling has decomposed the goal of cultivated land protection in China and implemented it from top to bottom, so that cultivated land data have nested attributes. Although related research on cultivated land changes has achieved fruitful results, these studies have neglected the scale effect created by the nested structure of cultivated land data, and it is easy for the policy to lose its effect in scaling. A two-layer linear model of the hierarchical linear model is constructed in this paper based on spatial autocorrelation and scale variance analyses to analyse the different spatial scales for cultivated land changes and reveal the interaction mechanism of the driving factors at different spatial scales. The results show the following: (1) The smaller the spatial scale of the study area, the easier the spatial correlation of the cultivated land quantity distribution. (2) An analysis of the driving factors of cultivated land change in Chongqing finds that 33.80% of the differences are from the functional block scale and 66.20% are from the district or county scale. (3) We found that the spatial scale has a certain impact on the effectiveness of the driving factors of cultivated land changes. Large-scale driving factors will change the correlation between small-scale driving factors and cultivated land change. In the future, the problem of scale effects should be considered in the field of cultivated land management, the effects of different driving forces at various scales should be considered and the scientific decomposition of cultivated land protection tasks according to the spatial scale should be carried out to improve the efficiency of the protection of cultivated land. [ABSTRACT FROM AUTHOR]

Studying the change laws of reconstructed soil quality and constructing succession models are the main components and tools of reconstructed soil quality evaluation for the supervision and management of reconstructed soil. However, the evaluation and management system of reconstructed soil quality suitable for the loess area needs to be improved. This paper aimed to clarify the succession law of reconstructed soil in an open-pit coal dump in the loess area on the temporal scale and to construct a succession model of reconstructed soil quality to evaluate and manage reconstructed soil. The Pingshuo coal mine, a representative open-pit coal mine in the loess area, is the study area. Field investigation and sampling, time-space substitution, and the combination of qualitative and quantitative research methods were used. The reconstructed soil quality succession model was constructed based on the soil quality index method. Results: (1) As the reclamation period increased, the physical and chemical properties of reconstructed soil significantly improved, and reconstructed soil quality generally reached the quality of the original landform after approximately 15 years of reclamation. However, after long-term reclamation, soil physical properties still limited the improvement of reconstructed soil quality to a certain extent. (2) After long-term reclamation, the difference in reconstructed soil quality between layers gradually decreased, and the reconstructed soil condition of the 0–10 cm soil layer was obviously better than that of the other layers. (3) We quantitatively constructed and verified the reconstructed soil quality succession model that is suitable for the loess area, which can be used in conjunction with adaptive management for the evaluation and management of reconstructed soil in the loess area. In conclusion, this study is of great significance to meet the real needs of dynamic evaluation and management of reconstructed soil quality in the loess area and to enrich the soil evaluation and management system at home and abroad. • Reconstructed soil can be restored to a better condition than original landform. • The soil physical structure and properties limit the reconstructed soil quality. • Reconstructed soil quality differs significantly among soil layers. • A soil quality model is built with reclamation period as independent variable. [ABSTRACT FROM AUTHOR]

The effect and quality of reclaimed mining area land in ecologically fragile areas have been the focus of the state, enterprises and academia. However, the research on the status quo and the interaction between the reconstructed topography, reconstructed soil and reconstructed vegetation in the reclaimed area needs to be further deepened, and its research value for subsequent ecological restoration and management in the mining area needs to be further expanded. In this study, the south dump of the Antianbao open-pit coal mine was taken as the research object. We used typical profile sampling methods, single-factor saliency analysis, Pearson correlation analysis and redundancy analysis to focus on exploring the influence of soil and topography on vegetation and to conduct a preliminary delineation of soil-layer functional areas. The results showed that (1) there was great heterogeneity in the quality of reclaimed land in the study area, in which the heterogeneity of vegetation status was particularly obvious, and the overall variation was medium or high. (2) In terms of topography, elevation and aspect significantly affected vegetation conditions. The soil factors that had the greatest impact on vegetation were the available potassium, total nitrogen, organic matter, gravel concentration in topsoil (0–30 cm), and the available phosphorus, organic matter, gravel concentration in deep soil (30–60 cm). (3) In the reclaimed land of the study area, the main functions of surface reconstructed soil provided nutrients for herbs and acted as a "channel" for the root system of vegetation, while the main functions of deep reconstructed soil provided nutrients for vegetation. Vegetation and soil play an important role in ecologically fragile systems. This study mainly summarizes the effects of soil and topography on vegetation in reclaimed land in the loess area, which is highly significant to improve and manage future reclamation sites at home and abroad, and to improve the homogeneity and system stability of reclamation sites. [Display omitted] • Fully analyzed the impact of 9 soil factors and 3 topographic factors on vegetation status, and found the main factors. • Use professional ecological analysis software Canoco 4.5 to conduct systematic multivariate statistical analysis. • Elevation and aspect are the main topographic factors that affect the vegetation status. • Different soil layers have different main soil factors that affect vegetation status. • Make a preliminary division of functional zones for different soil layers. [ABSTRACT FROM AUTHOR]

Determining the regulating factors of soil nutrient variations can guide the implementation of land reclamation measures in opencast coalmine regions. In this study, 132 soil samples were collected at 22 sample sites in the South Dump of Pingshuo opencast coalmine, and soil physicochemical properties were separately measured to obtain the related soil information. Geostatistical analyses were employed to analyze the spatial distribution patterns of soil organic carbon stocks (SOCD), total nitrogen stocks (TND), available phosphorus stocks (APD), and available potassium stocks (AKD) at 0–60 cm. The results showed that the spatial distributions of these soil nutrient stocks were characterized by moderate (TND) to strong (SOCD, APD, and AKD) spatial dependence. Meanwhile, the values of SOCD (16.4–60.1 Mg ha−1) and TND (1.9–15.5 Mg ha−1) were much higher than those of APD (0.022–0.095 Mg ha−1) and AKD (0.31–1.40 Mg ha−1). The statistical analyses indicated that the influence of afforestation on SOCD, TND, APD, and AKD was not significant, and the dynamic variations of soil nutrient contents were mainly regulated by soil pH in the South Dump. The findings of this study can provide some scientific guidance for soil nutrient management in the opencast coalmine regions of similar ecosystems. [ABSTRACT FROM AUTHOR]

Open-cast coal mining in China has developed rapidly due to its obvious advantages over underground mining. However, it may have negative ecological effects, such as biodiversity loss, water shortage, and soil erosion. Identifying and protecting the key areas with high importance for ecological sustainability are great challenges. The construction of an ecological security pattern (ESP) can improve landscape connectivity and reduce the fragmentation of ecological patches. Thus, it can be seen as an effective measure to protect regional ecological sustainability. In this study, taking the Pingshuo open-cast mining area as a case study area, ecological sources are identified through ecosystem structure and function, and corridors are extracted by constructing an ecological resistance surface, thus forming a valid ecological network. The results show that in 2018, the ESP in the study area included 11 sources with an area of 147.74 km2 and 17 corridors with a length of 92.11 km. Specifically, the ecological sources are mainly distributed in Taocun Township, Jingping Township, and Xiangyangbao Township. Among these 11 sources, sources 7 and 8 are reclaimed waste dump land, meaning that the land reclamation work in Pingshuo greatly promotes connectivity. Furthermore, dump 1 can be restored in the future by constructing three new corridors, which will greatly improve the landscape connectivity of Yuling Township. Overall, this study not only provides an effective framework for constructing and optimizing ESPs in ecologically fragile coal mining areas, but it also adds new insights to the concept of land reclamation in these areas. [ABSTRACT FROM AUTHOR]

Abstract: China has extremely scarce land resources compared to the world average. There is an urgent need for studies of the current situation and the trends in land-use change and assessment of the performance of land policies in China. Assessment of land-use change has long been hindered by a lack of accurate and reliable data. This paper uses the data obtained from the national land surveys of 1996 and land-use change surveys from 1997 to 2008, to analyze changes in land use and the policy dimension driving forces related to the changes, especially cultivated land, forestry land, grassland, as well as developed land. The aim of this analysis will be to derive the physical, social and economical driving forces of those changes to grasp the trends in land-use change and the effects of land policies and to formulate strategies for the protection and sustainable use of agricultural land. The results indicate that, although the overall change in land use was not large, cultivated land was significantly reduced and developed land rapidly increased. A great deal of high quality cultivated land was changed to developed land and low quality cultivated land generated from unused land, which has resulted in a serious threat to food supplies in China. Predictions using the methods of linear extrapolation and a BP neural network indicate that it is impossible to keep to a target of 0.12 billion hectares of cultivated land in the future under the mode of economic development used between 1996 and 2008. The results also indicate that the implementation of the laws and regulations about controlling the developed land and preserving cultivated land had significant effects on changes in land use, especially cultivated land and developed land. The results suggest that the changes in land use are closely related to economic fluctuation and the enaction and implementation of these land policies had a little time lag for cultivated land protection. There is a pressing need for China to use its limited land resources more efficiently and effectively by enacting or re-enforcing the laws and regulations on land resources protection and economic development, not only for its own growing population, but also the world. Therefore, we must formulate strategies for the protection and sustainable use of agricultural land. [Copyright &y& Elsevier]

Regional land use changes are an important part of global changes. The research on land use changes in the Three Gorges Reservoir Area of China attracts a lot of attention owing to the Three Gorges Dam building. The Three Gorges Reservoir Area becomes one of the important research areas. This study analyzed the transforming processes and traits of each land use type and the regional differences of land use changes during the past 30 years, summarized the distribution of different land use types in different buffer zones and regresses the equation areas and different buffer distances based on buffer analyses and regression analyses, and then analyzed the transforming rules in different buffer distances, got the optimal influence distances. The research results indicate that, (1) cultivated land lies at the northwest of the reservoir and was decreasing, however, the construction land was increasing, especially the urban construction land, a large number of land was flooded because of the reservoir water level rise; (2) urban area was sprawling quickly in developed and neighboring areas, and a great deal of cultivated land and a considerable amount of grassland were occupied; in the earlier time, rural settlements occupied lots of cultivated land and a sum of forestry land in the later time; (3) the optimum influenced distances for cultivated land and forestry land were 10-35 km, and for urban and rural settlements were in 5-20 km. Overall, this research can reflect the spatial-temporal characteristics of land use changes during the 30 years, and it is helpful for urban planning and land use planning in the reservoir area. [ABSTRACT FROM AUTHOR]

• Topography and vegetation cover types affected spatial variability of SBD. • SBD was generally distributed in stripes and patches in reclaimed land. • Spatial variability of SBD changed with the increase of soil depth. • The engineering and vegetation measures of improving SBD were explored. Controlling and adjusting the reconstructed soil bulk density (RSBD) in an artificially disturbed ecosystem is one of the main challenges in land reclamation. Exploring the spatial distribution of RSBD is the best starting point to analyze and improve reclamation technology. This study quantifies the spatial distribution pattern and variation of RSBD on reclaimed land in the loess area of China using geostatistical spatial interpolation and multiple regression analysis. Topography (platform, slope, and slope aspects), vegetation cover, soil particle size distribution, and soil erosion were found to affect the spatial variability of the RSBD. The boundary between the sunny slope and shady slope was considered to be the dividing line for the RSBD, which was generally distributed in stripes and patches. The RSBD was higher on the sunny slope than on the shady slope at 0–10 cm, while the opposite was observed at 20–40 cm. However, the RSBD at the depths of 40–60 cm increased from west to east, and the direction of the strong spatial variability also gradually changed from " Southwest ↔ Northeast " to " West ↔ East ". The unary quadratic regression equations accurately represent the variation laws of RSBD at different soil depths under different topography and vegetation cover (R2 > 0.90). Measures that utilize engineering and vegetation to improve the RSBD should be adjusted according to the specific landscape and topography. This study provides a theoretical basis for the improvement of the RSBD and the optimization of land reclamation technology used in opencast coal-mine dumps in the loess area. [ABSTRACT FROM AUTHOR]

[Display omitted] • Constructing an assessment framework for supply – demand risk of ecological products. • The supply – demand risk of ecological products was divided into eight levels. • Regulatory strategy for regional ecological supply – demand risk was discussed. Humans are facing increasing supply–demand risks of ecological products (EPs) due to the uncertainty of the interaction between ecosystems and social systems. To address this issue, a comprehensive framework for risk assessment and regulation is urgently need to identify areas and levels of risk that threaten human well-being. In this study, we constructed a framework for retrospective assessment and optimal regulation of supply–demand risks of EPs, which covers four indicators: the supply–demand index (SDI), the changing trend of SDI, the changing trend of supply, and trade-offs and synergies. Taking Qinghai Province in the northeast of the Qinghai-Tibet Plateau in China as an example, we conducted a case study on five types of EPs: food production, water conservation, carbon sequestration, soil retention, and outdoor recreation. Our results showed that various types of EPs were basically in the state of supply exceeds demand, with significant spatial differences in supply–demand risk levels. Areas with high risk levels were mainly distributed in urban concentrated development areas in the eastern part of the research area, and the spatial matching of supply and demand in these areas often present high supply and high demand. In addition, for the supply–demand risk of different levels of EPs, we proposed intra-regional and cross-regional optimization regulation strategies, combining the spatial matching status of supply and demand of EPs. It can help decision-makers improve the efficiency of the allocation of EPs supply and demand and the scientific nature of policy formulation at a regional scale. [ABSTRACT FROM AUTHOR]

• All the reclaimed soil nutrients tested increased between 2013 and 2017. • Land use type and reclamation age interacted to affect reclaimed soil nutrients. • The most improved SAP, SAK, STN and SOM were mainly distributed in grassland. • Grassland with alfalfa should be considered in the initial stage of reclamation. • Hybrid models of trees, shrubs, and grasses should be explored in the long term. Soil nutrients are critical indicators of land reclamation effects and play significant roles in soil restoration in degraded mining areas; however, few studies have analyzed the characteristics and variations in soil nutrients after reclamation in ecologically fragile regions on the Loess Plateau. To analyze the spatial and temporal variations in reclaimed soil nutrients, an experimental field was established in an inner reclaimed dump consisting of four land use types (cultivated land (CL), forestland (FL), grassland (GL), and barren land (BL)) in the Antaibao mine on the Loess Plateau of China. Sampling was conducted in 2013 and 2017, with 78 and 81 sampling points, respectively. The soil available phosphorus (SAP), soil available potassium (SAK), soil total nitrogen (STN) and soil organic matter (SOM) contents at depths of 0–20 cm were measured at each sampling point, and the variations in soil nutrients were analyzed using two-way multivariate analysis of variance, geostatistical analysis, and correspondence analysis. This study revealed the following: (1) All the reclaimed soil nutrients tested increased between 2013 and 2017. (2) There were significant differences in the SAP, SAK, STN and SOM contents among land use types and reclamation ages, and land use type and reclamation age had an interaction effect on the reclaimed soil nutrients. (3) The spatial distributions of the SAP, SAK, STN and SOM contents in 2017 were significantly different from those in 2013 but were almost consistent with the distributions of soil nutrient changes between 2013 and 2017. (4) The most improved SAP, SAK, STN and SOM (SAP-VI, SAK-VI, STN-VI, and SOM-VI) were predominantly distributed in the GL, and there was no obvious trend for the other land use types. These findings are significant for the restoration of reclaimed soil nutrients and provide reasonable land use type options for land reclamation in coal mining areas, especially in ecologically fragile areas on the Loess Plateau. [ABSTRACT FROM AUTHOR]

The thermal environment is a crucial part of ecological environments. It is vital to study the distribution and generation of thermal environments for regional sustainable development. Mining area, agricultural area and urban area were taken as the research object, and remote sensing data were used to study the spatiotemporal distribution characteristics of the thermal environment. The relationship between the thermal environment and land use types was analyzed, and the effect of mining and reclamation on the thermal environment was emphasized. The main findings were: (1) the thermal effect zone in the study area was dispersed. The area ratio of the thermal effect zone accounted for 69.70%, 68.52%, 65.85%, 74.20% and 74.66% in the year 2000, 2003, 2009, 2013 and 2018, respectively. The contribution to the overall thermal effect was in the order of agricultural area > mining area > urban area. (2) The proportion of forest and the average grid temperature always showed a significant negative correlation in different scales and had the highest correlation and the greatest influence. (3) The land surface temperature (LST) of opencast areas was higher than the surrounding temperature, and the temperature difference was 3-5 °C. The LST of reclaimed sites was lower than the surrounding temperature, and the temperature difference was -7 to 0 °C. The quantitative study found that reclamation mode, shape and spatial location could affect the cooling effect of the reclaimed site. This study can provide a reference for the mitigation of thermal effects and the identification of influences of mining and reclamation on the thermal environment in the coordinated development of similar regions.

The mine-agriculture-urban compound area formed under the combined effects of natural conditions, mineral resource endowments, and historical development is affected by severe man-made disturbances, and faces a prominent contradiction between economic development and ecological protection. Guiding the future development is an urgent problem in this region. This research used image data, logical reasoning, and empirical analysis, based on social and economic statistics and land-use data, to analyze the typical characteristics and problems of the social-ecological system in the mine-agriculture-urban compound area. Moreover, we identified future directions for the region guided by policy documents and built a philosophy framework for sustainable development and management of the region based on the concept of adaptability. The results showed the following: (1) At present, the output value of the coal industry accounts for 84.10% of the total regional output value, severely disturbing its social-ecological system, which needs to be protected and restored under human guidance and management. (2) The future development of this region depends on the one hand on green mining, and on the other hand, it is necessary to fully tap the potential of arable land and livestock farms to develop efficient and intensive agriculture. (3) The key contents of the social-ecological system management of the mine-agriculture-urban compound area include resolving the contradiction between development and protection, ensuring development, optimizing industrial structure, and safeguarding public interests. In conclusion, this research can expand the connotation and application scope of adaptive management and provide a reference for such areas facing the prominent contradiction between development and protection.

Soil erodibility (K factor) and saturated hydraulic conductivity (Ks) are essential indicators for the estimation of erosion intensity and can potentially influence soil nutrient losses, making them essential parameters for the evaluation of land reclamation quality. In this study, 132 soil samples from 22 soil profiles were collected to measure soil physicochemical properties (e.g., particle size distribution, bulk density and soil nutrient content) and calculate the K factor and Ks of reclaimed soils across the South Dump of the Pingshuo opencast coalmine in the Loess Plateau, China. Geostatistical analysis and the kriging interpolation were employed to quantify the spatial variations in the K factor and Ks in different layers. The results show that the K factor at 0−10 cm is obviously lower than that of other soil layers due to the external input of organic matter, while the Ks tends to decrease along with soil depth. Horizontally, the K factor at 0−10 cm and 50−60 cm shows a decreasing tendency from west to east, while that of other soil layers seems not to show any spatial distribution pattern along latitude or longitude. Meanwhile, the Ks at 0−10 cm presents a striped distribution pattern, while that of other soil layers shows a patchy pattern. On the other hand, the independent-sample t-test and Spearman’s correlation analysis were carried out to determine the effects of soil erodibility on total nitrogen (TN), soil organic matter (SOM), available phosphorus (AP) and potassium (AK). Overall, the K factor is negatively correlated with TN (r = −0.362, p < 0.01) and SOM contents (r = −0.380, p < 0.01), while AP and AK contents are mainly controlled by Ks. This study provides insight on the optimization of reclamation measures and the conservation of soil nutrients in reclaimed land of similar ecosystems.

Land reclamation is a dynamic ecological restoration process, and rehabilitated vegetation requires a certain amount of time to develop, stabilize and mature. The development characteristics of rehabilitated vegetation at different land reclamation stages are significantly different, and these differences can be used to identify the key stages of land reclamation. In this study, normalized differential vegetation index (NDVI) time series data from the western dump of the Pingshuo opencast coal area on the Loess Plateau from 1989 to 2018 were collected and analyzed by fluctuation analysis and filter processing with the Best Index Slope Extraction and Wavelet Transform (BISE-WT) filter to reveal the succession characteristics of rehabilitated vegetation. Then, the key periods of land reclamation under different vegetation types (arbor, shrub, arbor-shrub, and grass) in the dump were determined by S-logistic function fitting and derivative analyses. The NDVI time series changes in land parcels reclaimed in different years exhibited different interannual change characteristics. Based on the number of years required for the rehabilitated vegetation to reach a stable state, the average development period of land reclamation in eligible units in the mining dumps was thirteen years, including ten years in the rapid development period and three years in the steady development period. The differences in land reclamation periods among the different vegetation types were significant (α = 0.05), and the number of years required for each period mainly followed the order of arbor > arbor-shrub > shrub > grass. Analyzing the vegetation succession characteristics and identifying the key periods of land reclamation for different vegetation types is conducive to dynamically evaluating land reclamation effects and is expected to provide a basis for strengthening the implementation of manual intervention measures in reclaimed mining areas., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Soil construction and revegetation are essential for ecological restoration in mining areas. The influence of vegetation on the horizontal and vertical distribution patterns of soil properties should be fully understood. However, most studies on reconstructed soils in mining areas only concentrate on the surface soil, without exploring the vertical variations in soil properties. Overall, this study aims to explore the potential mechanisms by which surface vegetation exerts some influence on the spatial distribution of soil physicochemical properties, and to provide some insight into revegetation and soil reclamation in mining areas. Descriptive statistics and one-way analysis of variance (one-way ANOVA) were employed to evaluate the differences in the soil physicochemical properties in horizontal and vertical directions under different land-use types in the south dump of Antaibao opencast mine in Pingshuo, Shanxi Province, China. The main results of this study are as follows: (1) In the horizontal direction, except for the strong variation (variation coefficient ≥ 100%) in soil organic matter (SOM) content at some depths, the degree of variation in other soil physicochemical properties at various depths was moderate or weak (variation coefficient < 100%). The soil physicochemical properties gradually remained constant after years of reclamation. In the vertical direction, the soil bulk density (SBD), soil porosity, SOM content, soil C/N ratio, soil total nitrogen (STN) content, soil available phosphorus (SAP) content, and soil available potassium (SAK) content showed significant variations ( p < 0.05) between soil depths. In contrast, no significant difference was found for other physicochemical properties. (2) The SBD, STN, SAK, soil porosity, and soil clay content were significantly different ( p < 0.05) under different vegetation cover types, but the influence of vegetation on other soil physicochemical properties seemed to be limited. The results reveal that trees have a stronger ability to reduce soil grain sizes and enhance SAP contents than shrubs or herbs; however, the beneficial effects of herbs on the physicochemical properties of shallow soil are more obvious than those of trees and shrubs. (3) This study indicates that more shrubs and trees should be planted in the areas with low vegetation coverage, and more measures should be taken to improve soil physicochemical properties in order to prevent the occurrence of large-scale degradation. The reconstruction of soil structure should be preferentially considered in the process of soil reconstruction and revegetation in areas under similar conditions. Herbs should first be planted in the early reclamation stage. At the same time, shrubs or trees can be adopted in the middle and late stages of vegetation reconstruction in order to achieve comprehensive revegetation.

In order to obtain the typical soil physical properties of reclaimed land more quickly and accurately, the South Dump of the China Coal's Antaibao Open-Pit Mine in Pingshuo was focussed on in this paper, and ground penetrating radar (GPR) technology was utilized to detect the soil physical properties of reclaimed land in the mining area. The soil profile sampling and GPR detection methods were used to acquire the data. The gravel content of surface soil was analyzed by counting the number of isolated gravel signals in GPR images. The change of effective soil thickness was analyzed by establishing the fitting relationship between calibration depth and GPR image depth. The Topp's model was validated by comparing its inversion with the measured soil volumetric water content. And the Topp's model was further validated by the soil volumetric water content obtained from the Topp's model and which obtained from the wave velocity inversion. The results are as follows: (1) Based on the number of isolated gravel signals in GPR images, we could qualitatively analyze the gravel content of surface soil reclaimed in the mining area. As the number of isolated gravel signals was greater, the gravel content of the surface soil was higher. (2) Using the known relative permittivity, electromagnetic wave velocity, and soil volumetric water content, the calibration depth and the reflection depth of the target (calibrator) of the GPR images were segmented, and the correlation between them is high. The fitting relationship (R 2 ) of each segment was higher than 0.940, and the average value of the five-segment R 2 was 0.966, which indicated more accurate detection of the effective soil thickness of the reclaimed land in the mining area. (3) GPR could be used to detect the soil volumetric water content of reclaimed land in mining area, and Topp's model was used for calculation of soil volumetric water content. The average deviation rate between the values from Topp's model and the measured values was 12%, and the average absolute value of the difference was 2%. In summary, the benefits of using GPR to detect soil physical properties of reclaimed land in mining area are as follows: (1) GPR can be used to detect soil layer thickness and surface gravel content faster and more accurately. (2) Topp model can also be used to calculate the soil moisture content of non-natural deposits such as reclaimed land in mining area.

Studies of soil bulk density (BD) spatial variations of land reclaimed after mining have become a focus of land reclamation and ecological restoration research. However, there have been few studies on the relationship among the reconstructed BD, terrain conditions, and vegetation growth. We examined the southern dumping site of the Pingshuo Antaibao open-pit coal mine located in a loess area in China. Field sampling data, digital elevation models (DEMs), and high-definition images were obtained, and indoor testing, geostatistics, and inverse distance weighting (IDW) were applied. This paper aims to analyze the spatial distribution law of the reconstructed BD and focus on its relationship with slope and vegetation allocation models. We demonstrated that (1) BD increased with soil depth and varied moderately within each layer. (2) The BD variation amplitude of the top 0-20-cm soil layer in both the east-west and south-north directions was small and more similar in the east-west direction than in the south-north direction, which was affected by herbaceous root systems. In the next four layers from 20 to 60 cm, the variation in BD in the east-west direction was far larger than that in the south-north direction, which was affected by vegetation classification. (3) On the whole, BD decreased with increasing slope, but when the slope was between 0° and 21°, BD exhibited a specific change law. (4) From the perspective of vegetation classification, the orders of magnitude of BD in the 0-20-cm and 20-60-cm layers differed. Overall, BD in areas vegetated with Korshinsk Peashrub was the lowest, and BD was moderate in areas with mixed vegetation, while BD was the highest in areas without vegetation or only vegetated with Black Locust. The mixed grass-bush-tree or bush-tree mode attained the best effect in regulating BD. These results can improve the basic principles of land reclamation in mining areas and provide a basis for further optimizing land reclamation technology in practice.

Scientifically determining the characteristics of arable land use in different regions is significant in promoting arable land protection. Most studies on the changes in arable land focus on an isolated analysis of the impact of urban development on arable land. Studies on the influence mechanism of regional spatial forces in different cities from the macro perspective are limited. A gravity model and ArcGIS spatial analysis methods were used to analyze the characteristics and driving mechanisms of arable land changes in different urban function orientations from the perspective of interregional economic interaction. We hope to provide guidance for the establishment of arable land protection in a similar city circle. The results indicated the following: (1) During the study period, the geographic range of arable land with strong dynamic changes (average annual change exceeding 1.5%) gradually widened from the core area to the surrounding area, while the annual change rate decreased. (2) There is a strong correlation between the change in arable land use and the scope of gravitational action. The dynamic changes in arable land in areas with strong gravitational relationships with the core area are strong, while in the weak gravitational areas that are less affected by the core area, the average annual rate of change is nearly below 1%. (3) In the 10-year study period, the overall changing trend of the radiation circle in the core area expanded. The gravitational value where the breaking point falls within its own administrative division is more related to the change of its arable land area, and the greater the gravitational attraction is, the more likely the correlation. In a city circle, it is essential to both protect arable land resources and promote coordinated economic development. Future research on arable land utilization in different city circles should consider overall area development. Different functional areas can be determined by calculating the gravitational value, then regional development potential and key development types can be determined, and arable land protection measures can be optimized based on these functional areas.