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.

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.

The impacts of climate change on the relationship between fluvial processes and dune landform evolution have been studied. However, the chronology data used to examine this relationship are deficient. The Keriya River has a glacial origin in the Kunlun Mountains on the south margin of the Tarim Basin. The river flows into the Taklimakan Desert, the second largest shifting-dune desert in the world. The dry channels and shifting dunes in this area provide an ideal opportunity to investigate fluvial and aeolian landform evolution processes and their relationship with climate change. We investigated this area during 2008-2011 and obtained 18 fluvial sediment samples from 16 sections for optically stimulated luminescence (OSL) dating. The results show that the ages ranged from 3.4-44.1 ka. Most of the samples (13) were Holocene in age, around 11 ka, 8-9 ka, 5-6.5 ka, 4.6 ka, and 3.4-3.7 ka and were distributed along ancient river channels around sites of Yuansha and Karadun. Two samples close to the Hotan River (38-47 ka) fall within the Marine Isotope Stage 3 (MIS3). Three samples (from one section) were located near ancient channels flowing towards the Yuansha Site and had ages of around 14.5 ka, i.e., during the Last Glacial Maximum (LGM). The analyses of the sediment samples and OSL ages suggest that the Keriya River flooded in the Holocene, the LGM, and MIS3. Fluvial sediments provided the source material for the dunes, and fluvial processes affected the landform evolution in the lower Keriya River. Our results suggest that most of the dunes covered in fluvial sediments in the lower reaches and the area west of the Keriya River developed since the Holocene. This differs from the results of previous studies, which suggested that they developed since the Han (202BC-220AD) and Tang (618-907AD) dynasties. The OSL ages of the fluvial sediments are consistent with the reported deglaciation (after glacial advance) ages in the alpine mountains surrounding the Tarim Basin. This suggests that climate fluctuations may have affected the occurrence of floods and the formation of dunes in the Taklimakan Desert.

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 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.

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.

Vegetation plays a key role in maintaining ecosystem stability, promoting biodiversity conservation, serving as windbreaks, and facilitating sand fixation in deserts. Based on the Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index (MODIS NDVI) and climate data, a Theil-Sen median trend analysis combined with the Mann-Kendall test and partial correlation and residual analyses were employed to explore spatiotemporal patterns of vegetation dynamics and key drivers in the Badain Jaran and Tengger deserts and Mu Us Sandy Land. Data were collected during the growing season between 2001 and 2020. Further analyses quantified the relative contribution of climate variation and anthropogenic activities to NDVI changes. Results revealed a predominantly increasing trend for average NDVI. The spread of average annual NDVI and growth trends of the vegetation were determined to be influenced by spatial differences. The area with improved vegetation was greater than that of the degraded region. Climate variability and human activities were driving forces controlling vegetation cover changes, and their effects on vegetation dynamics varied by region. The response of vegetation dynamics was stronger for precipitation than temperature, indicating that precipitation was the main climate variable influencing the NDVI changes. The relative role of human activities was responsible for > 70% of the changes, demonstrating that human activities were the main driving factor of the NDVI changes. The implementation of ecological engineering is a key driver of increased vegetation coverage and has improved regional environmental quality. These results enhance our knowledge regarding NDVI change affected by climate variation and human activities and can provide future theoretical guidance for ecological restoration in arid areas.

Most terrestrial models synchronously calculate net primary productivity (NPP) using the input climate variable, without the consideration of time-lag effects, which may increase the uncertainty of NPP simulation. Based on Normalized Difference Vegetation Index (NDVI) and climate data, we used the time lag cross-correlation method to investigate the time-lag effects of temperature, precipitation, and solar radiation in different seasons on NDVI values. Then, we selected the Carnegie-Ames-Stanford approach (CASA) model to estimate the NPP of China from 2002 to 2017. The results showed that the response of vegetation growth to climate factors had an obvious lag effect, with the longest time lag in solar radiation and the shortest time lag in temperature. The time lag of vegetation to the climate variable showed great tempo-spatial heterogeneities among vegetation types, climate types, and vegetation growth periods. Based on the validation using eddy covariance data, the results showed that the simulation accuracy of the CASA model considering the time-lag effects was effectively improved. By considering the time-lag effects, the average total amount of NPP modeled by CASA during 2001-2017 in China was 3.977 PgC a^-1, which is 11.37% higher than that of the original model. This study highlights the importance of considering the time lag for the simulation of vegetation growth, and provides a useful tool for the improvement of the vegetation productivity model.

Snowmelt runoff is a vital source of fresh water in cold regions. Accurate snowmelt runoff forecasting is crucial in supporting the integrated management of water resources in these regions. However, the performances of such forecasts are often very low as they involve many meteorological factors and complex physical processes. Aiming to improve the understanding of these influencing factors on snowmelt runoff forecast, this study investigated the time lag of various meteorological factors before identifying the key factor in snowmelt processes. The results show that solar radiation, followed by temperature, are the two critical influencing factors with time lags being 0 and 2 days, respectively. This study further quantifies the effect of the two factors in terms of their contribution rate using a set of empirical equations developed. Their contribution rates as to yearly snowmelt runoff are found to be 56% and 44%, respectively. A mid-long term snowmelt forecasting model is developed using machine learning techniques and the identified most critical influencing factor with the biggest contribution rate. It is shown that forecasting based on Supporting Vector Regression (SVR) method can meet the requirements of forecast standards.

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.

Geomorphic dynamics of alluvial rivers in response to upstream damming have substantial impacts on navigation, habitat protection, and channel stability. The purpose of this study was to determine how flow and sediment regimes, and meander characteristics affect the morphological adjustment of bends in the Lower Jingjiang Reach (LJR) before and after the Three Gorges Project (TGP). Based on detailed field measurements and hydrological and topographic datasets from 1991 to 2016, banks and point bars morphodynamics of 12 continuous bends in the LJR were comprehensively analyzed. Point bars in the LJR mainly experienced a net deposition before the TGP operation, but substantially deteriorated with a net erosion rate of 4.6 million m³ yr^?1 in the post-TGP periods (2003-2016), and erosion on heads and upstream margins of point bars was a general adjustment pattern in the 12 bends. The most significant morphological changes of point bars and banks occurred in 2006-2011, indicating a delayed response of the channel evolution of the LJR to damming. Detailed observations suggested that the medium discharges (16,000-18,000 m³ s^?1) were the most contributive discharges in shaping the morphology of point bars and banks in the LJR after damming. In addition, we revealed the importance of sediment supply on meander deformation of the LJR, driven by sediment exchange over point bars, and more upstream planform deformation tended to occur in bends with high sinuosity (>2.0) in the LJR after damming. The relationship between meander deformation and sinuosity was manifested through the geometric adjustment range of point bars. The morphological adjustments of point bars in the highly curved or compound bends of the LJR were more conducive to cause flow deflections, leading to form concave-bank bars after the TGP operation.

Exploring the utilization effect of water-land resources under the evolution of dietary patterns is of great significance in achieving sustainable global food consumption and the effective allocation of national resources. Our selected study area was China, a country with rapidly changing dietary consumption patterns, and the research period was between 1987 and 2020. Based on the material called Chinese Dietary Guidelines 2021, this study introduced the “virtual water” and the “virtual land” to quantify the utilization effect of water-land resources under the evolution of Chinese dietary patterns. Results showed that the dietary patterns gradually changed from “cereal-vegetable-based consumption” to “diversified consumption”. Food consumption’s total water footprint (WF) increased from 471.1 Gm³ in 1987 to 848.8 Gm³ in 2020, with a growth rate of 80.2%. Moreover, the total land requirement for food (LRF) increased from 88.8 Mha in 1987 to 129.9 Mha in 2020, with a growth rate of 46.3%. Furthermore, the meat consumption was the major contributor to the increase in total WF (104.0%) and LRF (102.1%). In contrast to the balanced diet pattern, there was no waste of water-land resources consumption for the food consumption of urban-rural residents in China between 1987 and 2020. However, the consumption of water resources would gradually approach the resource cost under the balanced diet patterns. It would eventually break through the critical value and reach the state of resource waste. In addition, the findings showed that urban residents’ waste rate of water-land resources for meat consumption increased by 142.3% compared with that in 1987. The research results can provide scientific guidance for resolving the food crisis under the supply of water-land resources in China and have an essential reference for national food security and sustainable development of resources and environment.

The semiconductor industry typifies the international division of labor and exhibits significant structural differences in global trade in key product segments. The evolution of cross-border trade flows and dependency relationships, as well as trade organization patterns of manufactured products, equipment and materials for manufacturing, are investigated by constructing a global semiconductor trade relationship matrix and using the Gini coefficient and trade dependency index. It was found that: (1) the global semiconductor trade is highly spatially unbalanced, with materials and equipment trade in particular highly concentrated in a few countries on both the supply and demand sides; (2) China has replaced the US as the largest global semiconductor trade player and has shaped the regionalized system of manufactured goods and materials trade with East and Southeast Asian economies, but its equipment trade is highly dependent on Europe and the US; (3) the semiconductor production model has promoted the regionalization of the east and southeast Asia region in the trade of manufactured products and materials, and developed economies such as the US, the EU, Japan, and South Korea have maintained their monopolistic advantage in the trade of semiconductor equipment by building exclusive innovation networks and establishing trade barriers. The monopolistic nature of the semiconductor equipment trade and the regionalization of manufactured goods and materials have formed the characteristics of the global semiconductor trade and are likely to be further strengthened in future trade.

Understanding the radial growth trends of trees and their response to recent warming along elevation gradients is crucial for assessing how forests will be impacted by future climate change. Here, we collected 242 tree-ring cores from five plots across the Qinghai spruce (Picea crassifolia Kom.) forest belt (2600-3350 m a.s.l.) in the central Qilian Mountains, Northwest China, to study trends in the radial growth of trees and their response to climate factors with variable elevation. All the sampled P. crassifolia chronologies showed an increasing trend in the radial growth of trees at higher altitudes (3000-3350 m), whereas the radial growth of trees at lower altitudes (2600-2800 m) has decreased in recent decades. The radial growth of trees was limited by precipitation at lower elevations (L, ML), but mainly by temperature at higher elevation sites (MH, H, TL). Climate warming has caused an unprecedented increase in the radial growth of P. crassifolia at higher elevations. Our results suggest that ongoing climate warming is beneficial to forest ecosystems at high elevations but restricts the growth of forest ecosystems at low elevations.

Driven by urbanization and industrialization, arable land in hilly and mountainous regions of China is gradually becoming marginalized, with the extent of arable land abandonment rapidly expanding from poor-quality sloping arable land to high-quality terraces. The abandonment of large-scale terraces will lead to a series of socio-economic and ecological effects. A national sample survey was used to investigate the extent and spatial distribution of terrace abandonment in China, and a total of 560 valid village questionnaires from 329 counties were collected in the mountainous areas of China. The main findings are as follows: (1) The phenomenon of terrace abandonment was widespread throughout the country, with 54% of the total surveyed villages exhibiting terrace abandonment, and the area of abandoned terraces accounting for 9.79% of the total. (2) The degree of terrace abandonment is high in the south and low in the north. The most serious region with abandonment was the hilly and mountainous areas in the south, especially in the middle and lower Yangtze River region. (3) The main driving factors of terrace abandonment were rural labor migration, agricultural mechanization level, irrigation conditions, and transportation conditions for cultivation. Targeted measures should be taken based on the specific conditions of each area to alleviate terrace abandonment. Measures such as improving terrace mechanization are universally applicable. Specifically, low-quality terraces can be withdrawn orderly, and for high-quality terraces, multiple measures are needed to consolidate agricultural production, such as adjusting the planting structure, strengthening agricultural infrastructure construction, and encouraging the transfer of land-use rights as well as large-scale operation.

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.

The agglomeration of the rural e-commerce industry represented by Taobao villages has reshaped the existing urban and rural spatial organization and proposed a new urbanization model. This study identified the spatiotemporal characteristics of Taobao villages in Quanzhou city and built panel regression models to examine the impact of these villages on urbanization level, which is measured via nighttime light (NTL). The results show that (1) while the number of Taobao villages in Quanzhou city has increased rapidly, it has also experienced sporadic growth and monocentric agglomeration, finally forming a polycentric agglomeration pattern; (2) Taobao villages display a significant near-city tendency, and the urbanization level of towns with Taobao villages is higher than that of towns without Taobao villages; (3) the panel regression model highlights that Taobao villages have a significant positive impact on urbanization level. Taobao villages near the city exhibit a greater effect; meanwhile, those that are far away from the city cannot improve their urbanization level unless they reach a considerable degree of agglomeration. Rural e-commerce will become an important direction for the transformation of urban fringe areas, which provides a certain reference for the development of new urbanization in China.

The black soil area in Northeast China serves as a “ballast” to ensure China’s food security. Unreasonable development and utilization lead to serious black soil degradation in some areas and affect regional food production and economic and social development. In the context of the intensification of the contradiction between food supply and demand worldwide, we should pay more attention to the overall situation of regional sustainable development and seek for systematic, scientific, and economic solutions. This study establishes a regional all-for-one customization model of black soil granary on the basis of the regional system of human-land relationship, customized and accurate management, agricultural system theory, and agricultural informatization with the guidance of integrated geography concept. The aim of this regional all-for-one customization model is to systematically diagnose the key problems and leading factors of black soil degradation and determine a solution that combines the commonness and individuality of black soil protection from the perspective of multiscale linkage, multifactor coupling, and multitechnology cooperation. The regional all-for-one customization model of black soil granary integrates the two perspectives of “regional” and “customization” into the protection and comprehensive utilization of black soil for the first time. It adopts zoning, grading, and classification as the main strategy and big data and artificial intelligence as the main technical approaches. This model constructs three strategies of different scales by combining the “satellite-air-ground-network” 3D monitoring system and the all-for-one customization platform driven by big data and artificial intelligence. First, the “implementing strategies by regions” are implemented at the regional scale to formulate the regional agricultural resource allocation scheme and agricultural zoning, which can provide strategies to protect and utilize black soil effectively. Second, the “determining strategies in accordance with villages” are implemented at the village scale to formulate a black soil protection and utilization model for different categories of villages, which can promote the organic integration of black soil protection and rural revitalization. Third, a “one strategy for one field” concept is applied at the field scale to provide accurate strategies for soil restoration and yield improvement in a fixed, quantitative, and regular manner. Multiscale integrated demonstration and scheme verification of the regional all-for-one customization model of black soil granary are conducted in Qiqihar City at three scales, namely, region, village, and field, to solve the key issues in black soil protection and utilization and form a replicable and popularized system solution, thereby providing a model for the sustainable development of Chinese and global black soil agriculture. The proposed regional all-for-one customization model of black soil granary has important theoretical and practical value in promoting the high-quality development of regional agriculture and rural revitalization, and provides a demonstration model of land protection and utilization for the black soil area in China and the whole world.

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.

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.

Rust belt cities are largely threatened by a waste of urban space at their core; however, in developing countries where land resources are widely used as instruments for macroeconomic stabilization, urban periphery is also at risk of being underutilized due to land hoarding. Such geographic differences entail new knowledge about how, where, and why underutilized lands are regenerated in the city. Furthermore, rapid urban growth imposes development disparity and mixed underutilization issues on cities in developing countries; therefore, how the geo-information obtained by the regeneration of different underutilized lands differs will be valuable for urban planners and policymakers to make prudent trade-offs. To fill these gaps, we conducted a sequential investigation into the regeneration of underutilized lands in a representative rust belt city - Changchun City in Northeast China, in an attempt to measure the regeneration pattern and analyze the underlying determinants using the Classification and Regression Trees analysis. The results indicated that, of all underutilized lands, increments of vacant lot and remnant cultivated land continued to plague the expanding urban periphery during 2016-2019. In a way, reduced underutilized lands alleviated land use conflicts at the city core. Nearly 23% of the underutilized areas had been regenerated, dominated by realty development, with most converted to residential lands, ecological lands and industrial lands. On the contrary, conversion to transportation lands and parking lots seemed to avoid the rapidly expanding sites. The regeneration rates in a certain area can be increased by a multitude of factors, including denser, simply structured land underutilization, abundant ecosystem services nearby and accessibility to public infrastructures. Site conditions such as residential density and accessibility may have fueled the regeneration associated with residential purposes, while regeneration of industrial development was closely associated with the underutilization density and parcel regularity. This research provides an empirical paradigm for delivering regeneration geo-information across different underutilized lands, particularly for rust belt cities that are caught between a shrinking core and speculative periphery.

Using the system dynamics simulation software Vensim PLE, we built a model to simulate the development of resilient human settlement in Changsha. This model includes five subsystems: living, economy, society, ecology and engineering. The model simulates various scenarios, based on different parameter settings to predict the trend of human settlement from 2019-2040 in Changsha. It puts forward four development programs under different simulation scenarios. The results show that the current system of human settling lacks self-regulation and feedback, where simple increases in the economy and urbanization cannot drive the internal system to progress positively. In contrast, the resilient human settlement program is more reasonable and scientific, up to the year 2040, the production, living and ecological environment of residents will be markedly improved in terms of per capita disposable income, per capita floor space and medical insurance coverage; these will increase by 98.9%, 39.7%, and 170.7%, respectively. This system of developing resilient human settlement provides feedback according to the internal relation loops and thus drives itself to adjust and recover, achieving harmonious and sustainable development. In the forthcoming development, we should take the initiative to optimize economic development and upgrade industrial structures, establish emergency plans and response mechanisms to enhance human quality of life.

How the dynamics in soil loss (SL) and sedimentation are affected by land use/cover change (LULCC) has long been one of the most important issues in watershed management worldwide, especially in fragile mountainous river basins. This study aimed to investigate the impact of LULCC on SL and sediment export (SE) in eastern regions of the Koshi River basin (KRB), Nepal, from 1990 to 2021. The Random Forest classifier in the Google Earth Engine platform was employed for land use/land cover (LULC) classification, and the Integrated Valuation Ecosystem Services and Trade-offs (InVEST) Sediment Delivery Ratio model was used for SL and SE modeling. The results showed that there was a pronounced increase in forest land (4.12%), grassland (2.35%), and shrubland (3.68%) at the expense of agricultural land (10.32%) in KRB over the last three decades. Thus, the mean SL and SE rates decreased by 48% and 60%, respectively, from 1990 to 2021. The conversion of farmland to vegetated lands has greatly contributed to the decrease in SL and SE rates. Furthermore, the rates of SL and SE showed considerable spatiotemporal variations under different LULC types, topographic factors (slope aspect and gradient), and sub-watersheds. The higher rates of SL and SE in the study area were observed mostly in slope gradient classes between 8° and 35° (accounting for 83%-91%) and sunny and semi-sunny slope aspects (SE, S, E, and SW) (accounting for 57%-65%). Although the general mean rate of SL presented a decreasing trend in the study area, the current mean SL rate (23.33 t ha^-1 yr^-1) in 2021 is still far beyond the tolerable SL rate of both the global (10 Mg ha^-1 yr^-1) and the Himalayan region (15 t ha^-1 yr^-1). Therefore, landscape restoration measures should be integrated with other watershed management strategies and upscaled to hotspot areas to regulate basin sediment flux and secure ecosystem service sustainability.

The lower reaches of the Minjiang River and its adjacent areas were among the most active prehistoric archaeological areas in Fujian Province. The accumulation types of Neolithic archaeological strata are roughly divided into dune sites and dune/shell mound sites. The sites can also be roughly divided into estuarine, coastal, and sea-island sites based on their geomorphic features. The cultural development of these prehistoric sites is of great significance for understanding the migration and spread of Austronesian civilization. Based on luminescence dating of typical Neolithic sites on Haitan Island, their quartz-OSL (optically stimulated luminecesence) burial ages were determined. Synthesizing previously published results, the temporospatial distribution characteristics of the sea-island sites on Haitan Island are discussed, and the relationship between Neolithic human activities and regional geomorphic processes is analyzed. The results show that: (1) the spatial and temporal distribution of the Haitan Island Neolithic sites are closely related to small-scale geomorphic features and are controlled by mesoscale geomorphic processes. The sites were mainly distributed in the foothills of two high hills along an NNE-SSW trend. With an increase in altitude, the features were distributed as “single site (I) - superimposed site - single site (II)” and appear successively. Single type sites (I) mainly appeared at low sea level, whereas single type sites (II) mainly appeared at high sea level. Superimposed sites were not subject to sea level changes. The relative elevation of the superimposed sites in the study area indicates the optimal residential area for human activities in the region. The single site with an elevation lower than the optimal residential area was mainly restricted by the lowest residential area, whereas the single site at a higher elevation than the optimal residential area was mainly affected by livelihood patterns. (2) High sea level caused by the “backwater effect” in low latitude areas in the southern hemisphere, and coastal aeolian sand activity influenced by sea level fluctuations in the middle Holocene correspond well with human activities recorded in the cultural stratigraphy of sea-island type sites. The altitude of coastal aeolian sand accumulation can be used as an indirect index to estimate the age of coastal dunes.

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.

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.

This paper examines the process and internal mechanisms of rural ecommerce industry agglomeration and space reconstruction in metropolitan fringe areas, employing Lirendong village in Guangzhou, China, as a case study. Questionnaire surveys and in-depth interviews were utilized and interpreted through the perspective of the actor-network theory. The results show that, in Lirendong village, local government, processing enterprises, rural collectives, e-commerce entrepreneurial talent, and other key actors participate in the pursuit and realization of suburban land value according to their action logic. Actors jointly evolved and constructed the phased industrial processes and space value accumulation process of the e-commerce industry. The reconstruction process experienced three stages, including the government-led agricultural decentralization stage, the market-oriented industrialization stage, and the Internet+ stage dominated by the social network of fellow villagers. The development process has evolved from the dominance of exogenous forces to that of endogenous forces, and, as a result, the types and structures of rural land use are diversified. The spatial texture and rural environment of the traditional country gradually disappeared, forming a diversified mixed form of urban-rural land and mixed-use landscape of industrial, commercial, and residential land in vertical space. At the same time, the social network changed from a single and homogeneous social network of acquaintances to a multiple network of strangers.

As a new mode for Chinese overseas investment and a growth pole for industrialization and urbanization of the host countries, the overseas economic and trade cooperation zone (OETCZ) or overseas free economic zone (OFEZ) of China plays an important role under the Belt and Road Initiative. With the rising attention on OETCZ, studies regarding OETCZ have also increased. However, there is a lack of studies reviewing this topic’s progress, challenges and future directions. This paper employs a systematic review to examine the literature on the OETCZ along the Belt and Road, based on domestic and overseas studies. The results show that domestic studies account for a large proportion of the collected literature, compared to overseas studies. Interdisciplinary research focus includes inductive case studies from a classification perspective, deductive studies based on cultural and institutional perspectives, trade network and bilateral trade relations based on the perspectives of international trade and regional economy, spatial planning studies from urban planning perspective, and overseas comments and earlier studies on Japan’s and Singapore’s overseas parks from the geopolitical and international political perspectives. Despite diverse research contents and dramatic progress, limitations exist in current OETCZ-related studies, including a lack of exploration of the mechanism, questions and concerns from overseas scholars, sustainable development and other problems. Future studies should broaden and deepen research insights, including the “overseas free economic zones (OFEZ)” as a general designation to cover all other types of OETCZs, studies on the primary conditions of host countries, exploration of the theoretical issues behind China’s OETCZ, comparative study of OETCZs such as management structures, profit models, environmental standards and legal systems as well as popular issues questioned internationally.

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.