Cities and the countryside have long been an inseparable organic whole. China’s new model of high-quality urbanization requires integrated urban and rural development and rural vitalization. Problems inherent to urban areas are caused by problems inherent to rural areas, and vice versa. Such problems are closely linked, and the compound each other to create “urban-rural problems.” As such, rural vitalization is necessary to prevent problems associated with growing cities, and the new model of urbanization is required to prevent problems in rural areas. Based on a review of domestic and foreign research on integrated urban and rural development, this study analyzes the root causes of persistent urban and rural problems and their counterposing patterns on a theoretical level; analyzes the main factors and driving mechanisms as well as the underlying pattern and sustainability of integrated urban and rural development; constructs a measurement test for integrated urban and rural development; and proposes a triangular model of integrated urban and rural development. It confirms that China’s integrated urban and rural development is in the late period of urbanization, which features a high degree of integration and more urban areas and fewer rural areas. Subsequently, it will enter the final period of urbanization and a stage of deep integration, with more urban and fewer rural areas. In the future, it will be necessary to implement a strategy of deeply integrated urban and rural development and use new urbanization and rural vitalization to solve urban-rural problems and improve the quality of urban and rural development. New theories and methods of integrated urban and rural development will need to be created and an evaluation system to judge quantitatively the depth of integrated urban and rural development will need to be established, in order to create desirable urban and rural areas. Future efforts should aim to develop greater synchronization, deeper integration, and mutual success between the new model of urbanization and rural vitalization, so as to improve the high-quality development of, and modernize, both urban and rural areas.

As the world’s largest developing country, the ability of China’s agricultural resource utilization to effectively support the current and future food security goals has been affected by a variety of factors (e.g., transformed supply channels, tightening international situation and frequent emergencies) in recent years and has attracted extensive attention from the academic community subject to multiple factors. This study uses literature review, statistical analysis, and spatial analysis methods to systematically explore China’s food security situation in the context of farmland resource constraints. It is found that the demand-side pressures such as demographic changes, social class differentiation, and dietary structure adjustments derived from economic growth and rapid urbanization have placed extremely high expectations on food supply. However, the quantitative restrictions, utilization ways, and health risks of farmland resources on the supply side constitute a huge hidden concern that affects the stability of food production. Although China’s farmland protection system is undergoing a transition from focusing on quantity management to sustainable use, the matching and coordinating demand pressure and supply capacity for food security is unbalanced. Therefore, facing uncertain future development scenarios, policymakers should focus on building a resilient space for China’s farmland protection to withstand the interference of major emergencies. The existing farmland protection space policy can be integrated by establishing a national farmland strategic reserve system (based on resilient space), and further development of targeted use control measures for zoning, grading, and classification will help realize sustainable China’s farmland resources use.

Exploring the spatio-temporal variations of farmland landscape patterns in a traditional agricultural region can provide scientific support for decision-making on sustainable rural land use and rural vitalization development. This study established a comprehensive evaluation index for farmland fragmentation with multiple aspects (dominance, integrity, aggregation, regularity, and connectivity) at the county scale. The goal was to identify the evolution of farmland fragmentation in the traditional agricultural region of the Huang-Huai-Hai Plain during 2000-2015 and investigate underlying drivers using panel data of 359 counties. Results showed an accelerating but fluctuating fragmentation pattern of the farmland landscape. The indexes of dominance, integrity, and aggregation of farmland decreased most sharply, while the index of connectivity increased. Furthermore, the evolution of the farmland fragmentation pattern showed significant spatio-temporal heterogeneity, which is similar to the trajectory of urbanization and land use transition. Farmland fragmentation in municipal districts also emerged earlier and was more severe than in county-level cities and counties. Factors influenced by advancing urbanization include the proportion of artificial land, population density, and proportion of primary industry; these factors drove the evolution of farmland fragmentation. In contrast, the increase in income of rural residents and production efficiency of farmland were the key factors contributing to the improvement in farmland connectivity.

This essay combines the Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS) nighttime light data and the Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime light data into a “synthetic DMSP” dataset, from 1992 to 2020, to retrieve the spatio-temporal variations in energy-related carbon emissions in Xinjiang, China. Then, this paper analyzes several influencing factors for spatial differentiation of carbon emissions in Xinjiang with the application of geographical detector technique. Results reveal that (1) total carbon emissions continued to grow, while the growth rate slowed down in the past five years. (2) Large regional differences exist in total carbon emissions across various regions. Total carbon emissions of these regions in descending order are the northern slope of the Tianshan (Mountains) > the southern slope of the Tianshan > the three prefectures in southern Xinjiang > the northern part of Xinjiang. (3) Economic growth, population size, and energy consumption intensity are the most important factors of spatial differentiation of carbon emissions. The interaction between economic growth and population size as well as between economic growth and energy consumption intensity also enhances the explanatory power of carbon emissions’ spatial differentiation. This paper aims to help formulate differentiated carbon reduction targets and strategies for cities in different economic development stages and those with different carbon intensities so as to achieve the carbon peak goals in different steps.

Accounting for the gains and losses of ecological assets holds scientific significance in sustaining human well-being. Based on related research on ecological assets, we established a county-scale ecological asset accounting technology system by analyzing the temporal and spatial variations of county-level ecological assets in China from 1990 to 2018 and clarified the factors which caused the gains and losses of ecological assets. On these bases, optimization and promotion pathways were proposed. The results show that the number of counties dominated by farmland and forest ecological resources accounted for about 45% and 37% of the total counties, respectively. From 1990 to 2018, the quality of county-level ecological stock assets showed an increasing trend, while the water conservation volume decreased in nearly 70% of the counties. The number of counties with the gains (47%) and losses (37%) of ecological flow assets demonstrated spatial patterns which showed the same segmentation characteristics as the “Hu Huanyong Line”, that is, the counties in the vastness of northwest China experienced significant gains, while decreases were widespread in eastern and southern China. The change of ecological assets in more than 70% of the counties was driven by climate change and human activities. The average degree of impact of human activities driving the ecological asset gains in counties was about 80%, while that of climate change causing the ecological asset losses was about 60%. According to various ecological resource types, gain and loss status, and its driving factors, counties in China can be classified into five types: climate change mitigation, climate change adaptation, ecological resources restoration, ecological resources protection, and ecological resources management. Our results indicate that differentiated optimization and promotion pathways can be adopted to achieve desired ecological asset gains.

Spatial models are effective in obtaining local details on grassland biomass, and their accuracy has important practical significance for the stable management of grasses and livestock. To this end, the present study utilized measured quadrat data of grass yield across different regions in the main growing season of temperate grasslands in Ningxia of China (August 2020), combined with hydrometeorology, elevation, net primary productivity (NPP), and other auxiliary data over the same period. Accordingly, non-stationary characteristics of the spatial scale, and the effects of influencing factors on grass yield were analyzed using a mixed geographically weighted regression (MGWR) model. The results showed that the model was suitable for correlation analysis. The spatial scale of ratio resident-area index (PRI) was the largest, followed by the digital elevation model, NPP, distance from gully, distance from river, average July rainfall, and daily temperature range; whereas the spatial scales of night light, distance from roads, and relative humidity (RH) were the most limited. All influencing factors maintained positive and negative effects on grass yield, save for the strictly negative effect of RH. The regression results revealed a multiscale differential spatial response regularity of different influencing factors on grass yield. Regression parameters revealed that the results of Ordinary least squares (OLS) (Adjusted R² = 0.642) and geographically weighted regression (GWR) (Adjusted R² = 0.797) models were worse than those of MGWR (Adjusted R² = 0.889) models. Based on the results of the RMSE and radius index, the simulation effect also was MGWR > GWR > OLS models. Ultimately, the MGWR model held the strongest prediction performance (R² = 0.8306). Spatially, the grass yield was high in the south and west, and low in the north and east of the study area. The results of this study provide a new technical support for rapid and accurate estimation of grassland yield to dynamically adjust grazing decision in the semi-arid loess hilly region.

The energy dissipation of boundary resistance is presented in this paper based on the flow resistance. Additionally, the river morphology responses to the resistance energy dissipation are explored using the Gaocun-Taochengpu reach in the lower Yellow River as a prototype. Theoretical analysis, measured data analysis and a one-dimensional hydrodynamic model are synthetically used to calculate the energy dissipation rate and riverbed morphological change. The results show that the energy dissipation rate along the channel will increase in both the mean value and the fluctuation intensity with increasing discharge. However, the energy dissipation rate will first decrease and then increase as the flow section or width-depth ratio increases. In addition, the energy dissipation rate has a significant positive correlation with the riverbed stability index. The results imply that the water and sediment transport efficiency of the river channel can be improved by optimizing the cross-sectional configuration to fulfil the minimum energy dissipation rate of the boundary resistance under stable riverbed conditions.

The development of industrialization and urbanization has intensified the coupling of human activities and hydrological processes and promoted the emergence of socio-hydrology. This paper addresses the issue of socio-hydrology due to new development and social demand for hydrological sciences and sustainable development. Four key scientific issues are identified through systematic analysis and summary of the relative research and international progress, i.e., (1) the long-term dynamic process of socio-hydrological system evolution; (2) quantitative description and driving mechanism analysis of socio-hydrological coupling system; (3) prediction of the trajectories of socio-hydrological system co-evolution, and (4) integrated water resource management from the perspective of water systems. Moreover, opportunities and challenges for developing socio-hydrology are emphasized, including (1) strengthening the research of interdisciplinary theoretical systems; (2) improving and broadening socio-hydrological research technical methods, and (3) supporting integrated water resources management (IWRM) for sustainable utilization goals (SDGs). The review is expected to provide a reference for the future development of socio-hydrology discipline.

Henan, China, is likely the most populous agricultural province worldwide. It is China’s major grain-producing area, with a continuously increasing population (96 million), which is greater than 93% of countries worldwide. However, this province has been experiencing unprecedented urbanization recently due to national policies and measures, such as a plan to build the capital city of Henan into a national center, resulting in severe conflicts in land use that endanger food security regionally and globally. To facilitate decision-making on this problem, we explored the detailed urban-rural development of Henan by modeling these land-use conflicts. Conventional modeling of a region’s urban-rural development is to navigate trade-offs (a) solely between different land-use types (b) by assuming that each type provides a single service (e.g., croplands produce all the food), and (c) under a polynomial regression-based projection of population. In contrast, we considered both land-use type and intensity, resulting in a detailed land system for Henan. By introducing the concept of land system services (e.g., food production), we established a many-to-many relationship between land system classes and services. These allowed us to carry out the most comprehensive modeling of Henan’s urban-rural development under eighteen combined scenarios of population growth and land-use policies on food production. The modeling results of these scenarios provide a solid basis for making decisions regarding Henan’s urban-rural development. We also revealed the influence mechanism of population growth, land-use policies, and their combinations, highlighting the benefits of securing food production by agricultural intensification rather than merely expanding the area of cropland.

In recent years, Cadmium (Cd) pollution has been found in many soil geochemical surveys in Northern Zhejiang Plain, a crucial rice production area in East China, located in the lower Yangtze River. To more scientifically predict the effect of soil Cd on rice safety, data including 348 local rhizosphere soil-rice samples obtained in 2014 were used in this study. Meanwhile, we extracted 90% of random samples as variables based on soil Cd content (Cd_soil), soil organic matter (SOM), pH, and other indicators. In addition, a multivariate linear model for rice Cd content (Cd_rice) prediction based on the indicators including the soil Cd content (Cd_soil), the soil organic matter (SOM), and the pH value. The remaining 10% of random samples were used for the significance test. Based on the 2014 soil Cd content (Cd_soil14) and the 2019 soil Cd content (Cd_soil19), this study predicted Cd content in 2019 rice grains (Cd_p-rice19). The spatio-temporal variation of Cd_rice was contrasted in the five years from 2014 to 2019, and the risk areas of rice safety production were analyzed using the Geographical Information System (GIS). The results indicated that compared with the actual Cd content in 2014 rice grains (Cd_rice14), the proportion of Cd_p-rice19, which exceeded the standard food level in China (GB2762-2017), increased dramatically. Moreover, the high-value areas of Cd_rice distributed greatly coincidentally in these two years. By contrast, both Cd_rice and Cd_soil show very different spatial scales. The dominant reason is the distribution of the local canal systems, indicating that economic activities and agricultural irrigation may aggravate the risk of soil Cd pollution, thus threatening safe rice production.

Since the implementation of the Development of Western Regions in 2000, a series of major ecological construction projects have been implemented, leading to a series of changes in the ecological conditions and ecological services of western China. This study calculated the amount of ecosystem services in total in the western region from 2000 to 2019, and analyzed ecological changes and the characteristics of spatio-temporal variations in ecological services. A relevant analysis method was applied to explore the tradeoff and synergy of service. It was found that the area of settlements and wetland ecosystems in the western region increased significantly from 2000 to 2015, whereas grassland showed a downward trend year by year. The vegetation fraction showed a decreasing belt-like distribution from south to north. It showed a fluctuating increase during 2000 to 2019, with inter-annual and large spatial differences. The water conservation service (WCS) had a slight downward trend from 2000 to 2019, and the main decreasing areas were distributed in southeastern Tibet, the western part of the Three Rivers Source region, and the karst rocky desertification area. The soil conservation service (SCS) showed an increasing but fluctuating trend, with the greatest increases observed in the Loess Plateau region, western Sichuan and Yunnan, northwest Tibet, and southeast Tibet. The windbreak and sand fixation service (SFS) showed a downward trend, and the sharp decline was mainly in the central and western parts of Inner Mongolia, Tibet and parts of northern Xinjiang. Ecosystem supply and WCS, and SCS were mainly synergistic, which were found in areas north of the Qinling Mountains-Huaihe River (QM-HR) line, especially in Ningxia and Inner Mongolia. Ecosystem supply was mainly tradeoffs with SFS, and it was found in the agriculture-pastoral transition zone. The synergistic degree of ecosystem services in areas subjected to ecological engineering policy was greater than that in non-engineering areas. Quantitative assessment of ecosystem service changes and their tradeoffs is helpful for scientific ecological management and maximizing ecological benefits.

Water use efficiency (WUE) is an important variable to explore coupled relationships in carbon and water cycles. In this study, we first compared the spatial variations of annual gross primary productivity (GPP) and evapotranspiration (ET) using four GPP and ET products. Second, we selected the products closest to the flux towers data to estimate WUE. Finally, we quantitatively analyzed the impact of climate change and soil water content on WUE. The results showed that: (1) Four GPP and ET products provided good performance, with GOSIF-GPP and FLDAS-ET exhibiting a higher correlation and the smallest errors with the flux tower data. (2) The spatial pattern of WUE is consistent with that of GPP and ET, gradually decreasing from the northeast to the southwest. Higher WUE values appeared in the northeast forest ecosystem, and lower WUE values occurred in the western Gobi Desert, with a value of 0.28 gC m^?2 mm^?1. The GPP and ET products showed an increasing trend, while WUE showed a decreasing trend (55.15%) from 2001 to 2020. (3) The spatial relationship between WUE and driving factors reveal the variations in WUE of Inner Mongolia are mainly affected by soil moisture between 0 and 10 cm (SM0-10cm), vapor pressure deficit (VPD), and precipitation, respectively. (4) In arid regions, VPD and precipitation exhibit a major influence on WUE. An increase in VPD and precipitation has a negative and positive effect on WUE, with threshold values of approximately 0.36 kPa and 426 mm, respectively. (5) In humid regions, SM0-10cm, VPD, SM10-40cm, and SM40-100cm exert a significant impact on WUE, especially SM0-10cm, and weakens with increasing soil depths, these differences may be related to physiological structure and living characteristics of vegetation types in different climate regimes. Our results emphasize the importance of VPD and soil moisture in regional variability in WUE.

Analyzing the agricultural landscape patterns in mountainous areas is critical to clarify the dynamic changes and development direction of agricultural landscapes. This also plays a significant role in the rational planning and management of agricultural land. A theoretical framework for agricultural landscape pattern transitions in mountainous areas is proposed to fill the gap of current research with an empirical study in the Caotangxi Watershed, Three Gorges Reservoir Area (TGRA), China. The transition characteristics of agricultural landscape patterns from 2000 to 2018 as represented by sloping farmland, abandoned land, and orchards are analyzed from a holistic-local perspective. The results indicate that the orchards expanded along river valleys, and abandoned land expanded at high elevations, which led to reduced sloping farmland. This phenomenon gives regional landscape differences at the holistic and local levels. Namely, it enhances the region’s holistic landscape diversity but causes fragmentation and aggregation of landscape patches in local areas. The agricultural landscape pattern transitions within the farming range in the study area are manifested primarily in four modes: sloping farmland-orchard conversion type (FOCT), comprehensive conversion type (CCT), partially abandoned type (PAT), and wholly abandoned type (WAT). Each transition mode reveals different development stages of the mountainous agricultural landscape patterns. In general, the agricultural landscape pattern transition is driven by socioeconomic factors in mountainous areas of the TGRA and is bidirectional. This attribute is expressed as the transition from the traditional grain-planting landscape with an even distribution to the eco-economic win-win orchard in valleys and transitions from sloping farmland to abandoned land in high-elevation areas. Overall, the results of this study reveal the uniqueness of agricultural landscape pattern evolutions in China’s mountainous areas in recent decades, which has enlightened the in-depth understandings of rural land use and agricultural ecosystems in mountainous areas of the TGRA, as well as improvements in rural developments and ecological environments.

High-intensity land use and resource overloaded-induced regional land use spatial pattern (LUSP) are essential and challenging for high-quality development. The empirical studies have shown that a scientific land uses spatial layout, and the supporting system should be based on a historical perspective and require better considering the double influence between the current characteristics and future dynamics. This study proposes a comprehensive framework that integrates the resource environment carrying capacity (RECC) and land use change (LUC) to investigate strategies for optimizing the spatial pattern of land use for high-quality development. China’s Zhengzhou city was the subject of a case study whose datasets include remote sensing, spatial monitoring, statistics, and open sources. Three significant results emerged from the analysis: (1) The RECC has significant spatial differentiation but does not follow a specific spatial law, and regions with relatively perfect ecosystems may not necessarily have better RECC. (2) From 2020 to 2030, the construction land and farmland will fluctuate wildly, with the former increasing by 346.21 km² and the latter decreasing by 295.98 km². (3) The study area is divided into five zones, including resource conservation, ecological carrying, living core, suitable construction, and grain supply zones, and each one has its LUSP optimization orientation. This uneven distribution of RECC reflects functional defects in the development and utilization of LUSP. In addition, the increase in construction land and the sharp decline of farmland pose potential threats to the sustainable development of the study area. Hence, these two elements cannot be ignored in the future high-quality development process. The findings indicate that the LUSP optimization based on dual dimensions of RECC and LUC is more realistic than a single-dimension solution, exhibiting the LUSP optimization’s effectiveness and applicability.

Rapid economic and social change promotes to improve human wellbeing (HW), but poses threats to ecosystems and the environment. Studying the coupling relationship between HW and ecosystem services (ES) is crucial for informing high-quality development. Firstly, we built a comprehensive index system for HW assessment, and evaluated HW for 17 prefecture-level cities in Shandong province, China, from 2000 to 2018. Then, we quantified ES based on land use data. Finally, we assessed the coupling coordination degree and analyzed the relationships between HW and each type of ES value. The results were as follows: (1) HW values increased overall in Shandong, with the highest value in Jinan (0.8034) and the lowest value in Heze (0.4965) in 2018. (2) The total ES values for the 17 cities increased slightly. The ranking of 17 cities according to the ES value per unit area was different from the ranking according to the total ES value. (3) All 17 cities in Shandong were in the coordinated development phase after 2015, with increasing coupling coordination degrees. There were clear positive relationships between HW and ES. General and specific policy recommendations were proposed, providing scientific evidence and a reference for Shandong’s urban management and policy formulation.

Based on the carrying capacity of the resources and the environment, this article defines the connotation of the land multifunctional space (LMFS) from three aspects, ecological protection, agricultural production and urban construction, in the new era of land space planning system. Moreover, a framework is constructed for the coordinated development of the multi-functional oriented space to match the use of land space (ULS) with the supply of resources and environment (SRE). Based on this, the technology and methods of comprehensive evaluation, dominance recognition, and matching relationship division functions of the use of land space (FULS) and functions of the supply of resources and environment (FSRE) are discussed. The advantageous functions of the use of land space (AFULS) and advantageous functions of the supply of resources and environment (AFSRE) are also identified in the study area. A LMFS coordinated development system integrating “function position-comprehensive partition-regulation strategy” is proposed. Through the empirical study of Shandong province, we found that, first, the FULS of ecological protection space in the province is mainly found in high value areas, and the FSRE is mainly in low value areas, which has certain complementarity in the space. The FULS of agricultural production space is mainly observed in high value areas, the FSRE is mainly in middle value areas, and the spatial distribution is balanced and staggered. The FULS of the urban construction space and the FSRE are mainly in middle values areas, and the spatial distribution is basically similar. Second, the FULS in the study area is dominated by the single advantage of agricultural production and urban construction, while the FSRE has a relatively balanced distribution of the advantages of ecological protection, single agricultural production and compound advantages of agricultural production and urban construction, and urban construction and ecological protection. The matching between the two is mainly at high and middle levels. Specifically, 70% of the province’s land space still has a certain development and utilization potential, and 30% of ULS intensity is close to or exceeds the resource and environment carrying capacity. Third, considering the comprehensive impact of resource endowment, social and economic development and policy and institutional environment on different matching relationships, this paper constructs the land spatial development strategic pattern of “two screens-seven regions-multicore” positioning and “four regions-eight categories” hierarchical area of Shandong at the macro level, and puts forward a differentiated land space development strategy.

China’s Belt and Road Initiative (BRI) presents the world with a new era of inclusive globalization, which will shape urbanization patterns globally. This study considered the launch of BRI as a quasi-experiment, where we evaluated the BRI’s impact on urbanization by way of difference-in-differences (DID) and propensity score matching (PSM) methods. The results showed that the BRI exerted a significantly negative effect on urbanization in its first three years. Its positive effect emerged from the fifth year onwards, indicating that the BRI’s positive effect on urbanization required a period of practical experience. Heterogeneous analysis and placebo test were also conducted to verify the robustness of the model. The effects in low-income countries were revealed to have been much greater than in high-income countries, meaning the BRI had been conducive to promote local urban growth in underdeveloped economies. Finally, the geographical detector model was introduced to discuss the influencing mechanism of urbanization in BRI and non-BRI countries, showing external factors were the prominent driving forces in BRI countries, whereas internal drivers played an important role in non-BRI countries. Our findings indicated that the implementation of the BRI contributed to building global economic growth and supporting a shared future.

Central Asia (CA) is one of the most fragile regions worldwide owing to arid climate and accumulated human activities, and is a global hotspot due to gradually deteriorating ecological environment. The Amu Darya Basin (ADB), as the most economically and demographically important region in CA, is of particular concern. To determine the concentration, source and pollution status of heavy metals (HMs) in surface sediments of the ADB, 154 samples were collected and analyzed for metals across the basin. Correlation and cluster analysis, and positive matrix factorization model were implemented to understand metals’ association and apportion their possible sources. Cumulative frequency distribution and normalization methods were used to determine the geochemical baseline values (GBVs). Then, various pollution indices and ecological risk index were employed to characterize and evaluate the pollution levels and associated risks based on the GBVs. Results indicated that the mean concentrations of HMs showed the following descending order in the surface sediments of ADB: Zn > Cr > Ni > Cu > Pb > Co > Cd. The spatial distribution maps showed that Cr, Ni, and Cu had relatively high enrichment in the irrigated agricultural area; high abundances of Zn, Pb, and Cd were mainly found in the urban areas. Four source factors were identified for these metals, namely natural sources, industrial discharge, agricultural activities, and mixed source of traffic and mining activities, accounting for 33.5%, 11.4%, 34.2%, and 20.9% of the total contribution, respectively. The GBVs of Cd, Zn, Pb, Cu, Ni, Cr, and Co in the ADB were 0.27, 58.9, 14.6, 20.3, 25.8, 53.4, and 9.80 mg/kg, respectively, which were similar to the regional background values obtained from lake sediments in the bottom. In general, the assessment results revealed that surface sediments of the ADB were moderately polluted and low ecological risk by HMs.

Revealing the drivers and scale effects of water pollutant discharges is an important issue in the study of the environmental consequences during urban agglomeration evolution. It is also a prerequisite for realizing collaborative water pollutant reduction and environmental governance in urban agglomerations. This paper takes 305 counties in the Yangtze River Delta (YRD) as an example and selects chemical oxygen demand (COD) and ammonia nitrogen (NH₃-N) as two distinctive pollutant indicators, using the Spatial Lag Model (SLM) and Spatial Error Model (SEM) to estimate the drivers of water pollutant discharges in 2011 and 2016. Then the Multiscale Geographically Weighted Regression (MGWR) model is constructed to diagnose the scale effect and spatial heterogeneity of the drivers. The findings show that the size of population, the level of urbanization, and the economic development level show global-level increase impacts on water pollutant discharges, while the level of industrialization, social fixed assets investment, foreign direct investment, and local fiscal decentralization are local-level impacts. The spatial heterogeneity of local drivers presents the following characteristics: Social fixed assets investment has a strong promoting effect on both COD and NH₃-N discharges in the Hangzhou-Jiaxing-Huzhou region and the coastal area of the YRD; industrialization has a promoting effect on COD discharges in the Taihu Lake basin and Zhejiang province; foreign direct investment has a local inhibitory effect on NH₃-N discharge, and the pollution halo effect is more prominent in the marginal areas of the YRD such as northern Jiangsu, northern Anhui, and southern Zhejiang; local fiscal decentralization has a noticeable inhibitory effect on COD discharge in the central areas of the YRD, reflecting the positive impacts on improved local environmental awareness and stronger constraints of multilevel environmental regulations in the urban agglomeration. Therefore, it is recommended to guide greener development to reduce the water pollutant discharge; to embed an environmental push-back mechanism in the fields of industrial production, capital investment, and financial income and expenditure; and to establish a high-quality development pattern of urban agglomerations systematically compatible with the carrying capacity of the water environment.

Climate change will bring huge risks to human society and the economy. Regional climate change risk assessment is an important basic analysis for addressing climate change, which can be expressed as a regional system of comprehensive climate change risk. This study establishes regional systems of climate change risks under the proposed global warming targets. Results of this work are spatial patterns of climate change risks in China, indicated by the degree of climate change and the status of the risk receptors. Therefore, the risks show significant spatial differences. The high-risk regions are mainly distributed in East, South, and central China, while the medium-high risk regions are found in North and southwestern China. Under the 2°C warming target, more than 1/4 of China’s area would be at high and medium-high risk, which is more severe than under the 1.5°C warming target, and would extend to the western and northern regions. This work provides regional risk characteristics of climate change under different global warming targets as a foundation for dealing with climate change.

Land spaces function in capacities of urban development, agricultural production, and ecological conservation, among many others. Research of land space utilization efficiency (LSUE) and coupling coordination relationships among its subsystems are significant for sustainable land space development. In this study, taking the Urban Agglomeration in the Middle Reaches of the Yangtze River (UAMRYR) as the study area, we establish a measurement index system to evaluate the LSUE (2000-2018) and analyze its coupling coordination degree by utilizing an improved coupling coordination model. The main results include the following. (1) The average efficiency levels of urban space and agricultural space in the UAMRYR increased 2000-2018, while the average efficiency of ecological space declined. (2) The spatial pattern of the LSUE values varied greatly, with the distributions of high-efficiency and low-efficiency levels significantly different. (3) The coupling degree of LSUE includes three types, i.e., high-level coupling, break-in, and antagonism. Each coupling degree type was characterized by change over time. (4) The proportion of areas with high coupling coordination and moderate coupling coordination increased from 2000 to 2018, while the proportion of areas with basic coupling coordination, moderate imbalance, and serious imbalance declined during this period. Given that the spatial differentiation of the LSUE and its coupling coordination, it is necessary to implement a differential land space development strategy in the UAMRYR. This study is helpful to promote the efficient utilization and coordinated development of land space utilization systems.

General history of disasters in China suggests that China has frequently experienced two major natural disasters in its long history, one is from catastrophic earthquake events, and the other is from extreme climatic events, due to its unique active tectonic environment and climatic complexity. Although these two major natural disasters have caused great damage to human society, it remains unclear whether and how they affect Chinese dynasty alternation on decadal (emperor) timescales. Based on detailed comparisons between abrupt climatic changes, catastrophic seismic activities, and the history of Chinese dynasty alternation from 1000-2000 AD, we conclude that on decadal timescales, extreme drought (and/or flood) events could indeed significantly reduce agricultural production, cause severe food shortages and famine, and result in increases in population exile, rising food prices and inflation, and insufficient supplies for military defense, which could exceed social resilience and eventually lead to financial risks and social upheavals of the dynasties. In addition, catastrophic seismic events in the densely populated, agricultural areas of China, including the 1303 surface wave magnitude (M_s) 8.0 Hongtong earthquake, the 1556 M_s 8.25 Huaxian earthquake and the 1920 M_s 8.5 Haiyuan earthquake, caused more than 200,000 casualties and millions of victims to live in exile which was almost equivalent to the order of magnitude of those extreme climatic events-induced refugees. The secondary geological hazards related to the earthquakes (e.g., extensive landslides and soil erosion), which could last for decades, caused more casualties and reduced food production. Furthermore, great plague spread caused by the casualties could significantly increase psychological panic among the survivors, resulting in social instability. Therefore, catastrophic seismic events could also accelerate the collapse of the dynasties (e.g., the Ming dynasty) without immediate mitigation measures. This study indicates that catastrophic seismic activities, as well as extreme climatic events, could have great effects on the social structures and thus on the Chinese dynasty alternation on decadal timescales, which highlights the far-reaching implications of geological hazard research.

This paper examines the rise of informal economies in China, a hidden driving force overlooked in studies on China’s urbanization. Estimating the size of informal economies using the multiple indicators multiple causes model, the paper employs mathematical models to examine the driving effect of informal economies on urbanization and to reveal the paths by which such effect works. The results were as follows. (1) In 2018, the size of the informal economy in China accounted for 23.5% of GDP with an output value of 21.16 trillion yuan. (2) The informal economy had a driving effect on China’s urbanization, and every 1-percentage- point increase in its share of the GDP led to an increase of 0.291 percentage points in the urbanization rate. (3) The informal economy’s effect on urbanization showed regional differences, decreasing in size from the eastern to the central to the western regions. (4) The informal economy drives urbanization through four paths - by promoting foreign direct investment (FDI), fixed asset investment (FAI), social consumption (SC), and secondary sector employment (SSE). Their effect sizes are ranked in descending order as follows: FDI > FAI > SC > SSE. This paper contributes to theories on urbanization dynamics and process in China by highlighting the role of the informal economy as a hidden economic power lurking in the city.

Industrial agglomeration is a highly prominent geographical feature of economic activities, and it is an important research topic in economic geography. However, mechanism-based explanations of industrial agglomeration often differ due to a failure to distinguish properly between the spatial distribution of industries and the stages of industrial agglomeration. Based on micro data from three national economic censuses, this study uses the Duranton-Overman (DO) index method to calculate the spatial distribution of manufacturing industries (three-digit classifications) in the Beijing-Tianjin-Hebei region (BTH region hereafter) from 2004 to 2013 as well as the hurdle model to explain quantitatively the influencing factors and differences in the two stages of agglomeration formation and agglomeration development. The research results show the following: (1) In 2004, 2008, and 2013, there were 124, 127, and 129 agglomerations of three-digit industry types in the BTH region, respectively. Technology-intensive and labor-intensive manufacturing industries had high agglomeration intensity, but overall agglomeration intensity declined during the study period, from 0.332 to 0.261. (2) There are two stages of manufacturing agglomeration, with different dominant factors. During the agglomeration formation stage, the main locational considerations of enterprises are basic conditions. Agricultural resources and transportation have negative effects on agglomeration formation, while labor pool and foreign investment have positive effects. In the agglomeration development stage, enterprises focus more on factors such as agglomeration economies and policies. Internal and external industry linkages both have a positive effect, with the former having a stronger effect, while development zone policies and electricity, gas, and water resources have a negative effect. (3) Influencing factors on industrial agglomeration have a scale effect, and they all show a weakening trend as distance increases, but different factors respond differently to distance.

In arid and semi-arid environments, desert vegetation plays an important role in preventing soil erosion by wind and helps maintain the stability of desert and oasis ecosystems. Four types of typical desert vegetation, namely Populus euphratica, Haloxylon ammodendron, Nitraria sibirica, and Halostachs caspica, corresponding to different habitats (i.e., river bank, sand dune, desert, and salt marsh) were chosen as the model vegetation in this research. The δ²H and δ¹⁸O for rainwater, soil water, and plant water were applied to identify the water sources and quantify the proportions of different water sources used over the entire plant growth period (from March to October). The results showed that the precipitation δ²H and δ¹⁸O in the Ebinur Lake basin varied from -142.5‰ to -0.6‰ and from -20.16‰ to 1.20‰, respectively. The largest δ²H and δ¹⁸O values occurred in summer and the smallest in winter. The soil water δ²H and δ¹⁸O of the four habitats decreased gradually with increasing depth. The δ²H and δ¹⁸O values of water extracted from the stems of the four plants had similar variation trends, that is, the maximum was observed in spring and the minimum in summer. Among the four plants, H. caspica had the highest stable isotopic values in the stem water, followed by N. sibirica, H. ammodendron, and P. euphratica. The water sources and utilization ratios of desert vegetation varied across different growth stages. Throughout the growing period, H. ammodendron mainly used groundwater, whereas the water source proportions used by N. sibirica varied greatly throughout the growing season. In spring, plants mainly relied on surface soil water, with a contribution rate of 80%-94%. However, in summer, the proportion of deep soil water used was 31%-36%; and in autumn, the proportion of middle soil water used was 33%-36%. H. caspica mainly relied on topsoil water in spring and autumn, and the proportion of soil water in the middle layer slightly increased to 20%-36% in summer. P. euphratica mainly used intermediate soil water in spring with a utilization rate of 53%-54%. In summer, groundwater was the main source, with a utilization rate of 72%-88%, and only 2%-5% came from river water, whereas in autumn, the river water utilization rate rose to 11%-21%. The results indicated that there were significant differences in water use sources during the growing period for desert vegetation in arid areas. This research provides a theoretical basis for understanding water use mechanisms, water adaptation strategies, and vegetation restoration and management in arid areas.

Rapid economic development and human activities have severely affected ecosystem function. Analysis of the spatial distribution of areas of rapid urbanization is the basis for optimizing urban-ecological spatial design. This paper evaluated the spatial distribution of urbanization in the Beijing-Tianjin-Hebei (BTH) region, and then quantified the ecosystem services (ES) budget in the region based on an ES supply and demand matrix. The results showed that (1) urbanization patterns in the BTH region were relatively stable from 2000 to 2015, with clear patterns of low levels of urbanization in the northwest and high levels in the southeast; (2) areas with positive ES budget values were found throughout the region, except in built-up areas, with high ES supply areas concentrated in the northwest, and high ES demand areas in the southeast; (3) at both the county and prefecture-city levels, urbanization had negative, positive, and negative correlations with ES supply, demand, and budget, respectively; (4) the coupling coordination degree (CCD) increased, with high CCD values in the southeast. Based on these results, policy recommendations include strengthening rational land-use planning and ecosystem management, promoting the coordinated development of the economy and ecological function, and coordinating the provision of production-life- ecological functions.

There are debates regarding whether a wet and warm climate or a dry and cold climate dominated Holocene fire activity in northern China on the millennial timescale, and when human activities overtook climate change as the dominant control on fire occurrence in the region. Here we present a high-resolution fire history for the past ~15,500 years from a sediment core in Dali Lake, located in the foothills of the Greater Hinggan Mountains, one of the areas of highest fire risk in China. The results demonstrate that fire activity was rare during the last deglaciation (~15,500-11,700 yr BP), gradually increased at the beginning of the Holocene, and reached its highest level during ~9000-5000 yr BP, after which there was a decreasing trend. However, after ~2000 yr BP this decreasing trend ended, and the most prominent feature is a peak in fire activity during the Medieval Warm Period (MWP). Overall, fire activity corresponded well to changes in the East Asian summer monsoon (EASM) precipitation on the millennial timescale during ~15,500-2000 yr BP, but this relationship changed after ~2000 yr BP. We propose that fire activity in northern China on the millennial timescale during ~15,500-2000 yr BP was dominated by the biofuels reserve under the control of the EASM precipitation. In contrast, with the intensification of human activities after ~2000 yr BP, human activity caused a ~62%-73% increase in fire activity, which altered the fire-climate relationship that had previously prevailed in northern China. Our results indicate that a wet-warm climate (increased EASM intensity), rather than a dry-cold climate, was the dominant control on fire activity in northern China during 15,500-2000 yr BP on the millennial timescale, but that human activities played an important role in fire occurrence after ~2000 yr BP.

A scientific delineation of geographical boundaries reflects the cognitive level of scientific abstraction and systematic analysis of the spatial variation of geographical objects and is a basic scientific issue of geography. From the perspective of earth system science, this study first explicates the core issues (e.g., basic concepts, scientific contents, and basic properties) of geographical boundaries. Based on the principles of scientificity and systematicness, we then classify geographical boundaries in terms of intrinsic mechanisms, extrinsic appearance and scientific attributes. Furthermore, this paper analyzes the mathematical connotation and representation methods of geographical boundaries, discusses the characteristics of and differences between traditional and modern methods for geographical boundary delineation. Finally, we present a framework for a “geographical boundary model” with an integration of qualitative, quantitative, and positioning methods. Focusing on geographical boundary (a basic theoretical problem in geography), this study engaged in concept definition and method analysis, with the findings enriching the theory and methodology of geographical information science.

Identifying the dynamics of the eco-efficiency of cultivated land use (ECLU) is important to balance food security and environmental protection. The Yangtze River Economic Belt (YREB) is a vital region of national strategic development in China. However, the spatio-temporal characteristics and typical patterns of the ECLU in the YREB remain unclear. This study aims to reveal the spatio-temporal characteristics of the ECLU by using the super-efficiency slack-based measure (SBM) and a spatial autocorrelation model. The typical patterns of the ECLU were classified based on a decision tree algorithm. The results indicate that the overall ECLU increased from 0.78 to 0.87 from 2000 to 2019, dropping sharply in 2003 before rising again. Different reaches had similar trends. The local indicators of spatial association (LISA) cluster reflect that the spatial distributions of high-high and low-low agglomeration varied dramatically among these years. The ECLU was divided into three typical patterns considering the restriction of agrochemicals and water resources (RAW), cultivated land and agrochemicals (RCA), as well as technology (RT). Most cities belonged to the low ECLU category in RT pattern. Fully understanding the spatio-temporal characteristics and classification of the ECLU will provide a reference for decision-makers to improve the ECLU in different regions.