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.

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.

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.

The transition of human societies from high mobility to sedentary lifestyles had a profound impact on subsistence, technology, and the origin of civilization. Sedentism was influenced by various factors such as climate change, population growth, resource pressure, and technological innovation. The Tibetan Plateau, due to its alpine and hypoxic conditions, is an ideal region to study human adaptation to extreme environments. However, the prehistoric process of sedentism on the Tibetan Plateau is unclear and the chronological sequence and driving mechanism of sedentism on the Tibetan Plateau are still controversial. Previous studies have focused on the diffusion of agriculture from low to high elevation areas, with little attention given to the role of animal resources in sedentism. Seasonality analysis using animal remains is crucial in determining whether a site was occupied year-round. To establish the seasonal calendar of animal resource utilization, it is recommended to create a database of skeletal morphology, whole genome, and proteome of contemporary Tibetan Plateau fauna to aid in the identification of animal remains from archaeological sites. Thus, intricate web of human-animal-environment relationship and the role of animal resources in human sedentism on the Tibetan Plateau can then be evaluated.

Rapid urbanization has occurred in arid/semiarid China, threatening the sustainability of fragile dryland ecosystems; however, our knowledge of natural environmental constraints on multiscale urban lands in this region is still lacking. To solve this issue, this study retrieved 15-m multiscale urban lands. Results indicated that urban area increased by 68% during 2000-2018, and one-third of the increase was contributed by only three large cities. The coverage of impervious surface area (ISA) and vegetated area (VA) increased by 16.6% and 1.38%, respectively. Such land-cover change may be helpful in suppressing wind erosion and sand storms. We also found that the newly urban lands had relatively lower ISA and higher VA than the old urban lands, indicating an improved human settlement environment. Strong environmental constraints on urban expansion were identified, with cities in oasis urban environments (OUEs) that had water supply expanding 150% faster than cities in desert urban environments (DUEs). Urban development was also constrained by terrain, with 73% of the ISA expansion occurring in relatively flat areas. Overall, the aggregated pattern of urbanization and the increase in ISA and VA in the newly urbanized lands have improved water-use efficiency and ecological services and benefited desert ecosystem protection in arid/semiarid China.

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.

Elucidating the distribution of the grazing pressure requires an understanding of the grazing activities. In this study, we analyzed the grazing behavior of yaks in Three-River- Source Region (TRSR) and identified the main factors influencing the distribution of grazing intensity (GI) using trajectory data and remote sensing datasets. Our results revealed that a semi-resident transhumance strategy is employed in this region. The average grazing time (GT) of four GPS collars over the year was 11.84 h/day (N6), 11.01 h/day (N11), 9.25 h/day (N18), and 11.61 h/day (N24). GT was generally higher in warm seasons (summer and autumn) than in cold seasons (spring and winter). The average daily moving speed was found to be closely related to the pasture size of different herders and the seasons. Geodetector analysis identified the distance to camp (DOC) as the most important single factor influencing the distribution of GI, explaining up to 52% of the GI variations. However, relying solely on this factor may not accurately depict the actual GI distribution. When pairwise factors interacted, the explanatory power of the model increased, ranging from 34.55% to 63.26%. Our study highlights the importance of considering multiple factors when predicting grazing intensity, as grazing activities tend to cluster near settlements, but other factors may also be influential.

Exploring the coupling coordinated level of rural population-land-industry (PLI) and its underlying driving mechanism contributes to the scientific decision-making on rural sustainable development. This study assessed the coupling coordinated level of PLI based on an improved evaluation index system and then revealed the regional differentiation and driving mechanism in China’s rural areas in 2020. The results showed that the rural PLI coupling coordinated degree was 0.4694, and thus was in the stage of approximate incoordination. In addition, China’s rural PLI coupling coordinated degree formed a spatially heterogeneous pattern with high levels in the northeast, eastern and central regions, and the intragroup difference contributed more than 80% to the total difference. The rural PLI coupling coordinated level was influenced by the combined effects of rural kernel and peripheral systems, but the rural kernel system mostly determined the differentiation. In the future, rural areas should first exploit population quality improvement projects, land consolidation projects and industrial integration development strategies to promote benign mutual feedback of PLI. Second, driving factors should be comprehensively regulated by implementing a “one village, one product” strategy, breaking the urban-rural dual system, improving agricultural machinery subsidies policy, and promoting urban-rural integrated development.

The mass elevation effect (MEE) is a thermal effect, in which heating produced by long wave radiation on a mountain surface generates atmospheric uplift, which has a profound impact on the hydrothermal conditions and natural geographical processes in mountainous areas. Based on multi-source remote sensing data and field observations, a spatial downscaling inversion of temperature in the Tianshan Mountains in China was conducted, and the MEE was estimated and a spatio-temporal analysis was conducted. The GeoDetector model (GDM) and a geographically weighted regression (GWR) model were applied to explore the spatial and temporal heterogeneity of the study area. Four key results can be obtained. (1) The temperature pattern is complex and diverse, and the overall temperature presented a pattern of high in the south and east, but low in the north and west. There were clear zonal features of temperature that were negatively correlated with altitude, and the temperature difference between the internal and external areas of the mountains. (2) The warming effect of mountains was prominent, and the temperature at the same altitude increased in steps from west to east and north to south. Geomorphological units, such as large valleys and intermontane basins, weakened the latitudinal zonality and altitudinal dependence of temperature at the same altitude, with the warming effect of mountains in the southern Tianshan Mountains. (3) The dominant factors affecting the overall pattern of the MEE were topography and location, among which the difference between the internal and external areas of the mountains, and the absolute elevation played a prominent role. The interaction between factors had a greater influence on the spatial differentiation of mountain effects than single factors, and there was a strong interaction between terrain and climate, precipitation, the normalized difference vegetation index (NDVI), and other factors. (4) There was a spatial heterogeneity in the direction and intensity of the spatial variation of the MEE. Absolute elevation was significantly positively correlated with the change of MEE, while precipitation and the NDVI were dominated by negative feedback. In general, topography had the largest effect on the macroscopic control of MEE, and coupled with precipitation, the underlying surface, and other factors to form a unique mountain circulation system and climate characteristics, which in turn enhanced the spatial and temporal heterogeneity of the MEE. The results of this study will be useful in the further analysis of the causes of MEE and its ecological effects.

Current ecosystem models used to simulate global terrestrial carbon balance generally suggest that terrestrial landscapes are stable and mature, but terrestrial net primary productivity (NPP) data estimated without accounting for disturbances in species composition, environment, structure, and ecological characteristics will reduce the accuracy of the global carbon budget. Therefore, the steady-state assumption and neglect of elevation-related changes in forest NPP is a concern. The Qilian Mountains are located in continental climate zone, and vegetation is highly sensitive to climate change. We quantified aboveground biomass (AGB) and aboveground net primary productivity (ANPP) sequences at three elevations using field-collected tree rings of Picea crassifolia in Qilian Mountains of Northwest China. The results showed that (1) There were significant differences between AGB and ANPP at the three elevations, and the growth rate of AGB was the highest at the low elevation (55.99 t ha^-1 10a^-1). (2) There are differences in the response relationship between the ANPP and climate factors at the three elevations, and drought stress is the main climate signal affecting the change of ANPP. (3) Under the future climate scenario, drought stress intensifies, and the predicted decline trend of ANPP at the three elevations from mid-century to the end of this century is -0.025 t ha^-1 10a^-1, respectively; -0.022 t ha^-1 10a^-1; At -0.246 t ha^-1 10a^-1, the level of forest productivity was significantly degraded. The results reveal the elevation gradient differences in forest productivity levels and provide key information for studying the carbon sink potential of boreal forests.

Under the wave of globalization, some cities in China, especially the so-called “megacities” are entering or have already entered the stage of post-suburbanization. The study places Shanghai suburbs in the post-suburbanization landscape and takes Qingpu New Town as an example to systematically analyze the development and formation mechanism of post-suburbanization spaces. This study reveals the features of the post-suburbanization in China as follows. Firstly, In China, post-suburbanization is achieved based on industrialization as well as on the promotion of urbanization. Although urbanization has strengthened other functions of suburban spaces aside from living and production, the production attributes of suburbs remain stable. Secondly, post-suburbanization space with the new town as the development model is an important path for a new round of suburban space growth, it has expanded the space for capital accumulation in metropolitan areas, thus promoting the possibility of reorganizing economic activities within metropolitan areas. At the same time, it focuses on the integration of industries and cities, and the simultaneous development of urbanization and industrialization. In turn, this promotes the accumulation of capital centered on the urban environment and manufacturing production. Furthermore, China’s special institutional circumstance enables its government to organize various actors to form a growth alliance, which will act together in the production of post-suburbanization space.

Climate change is manifesting rapidly in the form of fires, droughts, floods, resource scarcity, and species loss, and remains a global risk. Owing to the disaster risk management, there is a need to determine the Dead Fuel Index (DFI) threshold of the fire occurrence area and analyze the spatio-temporal variation of DFI to apply prevention measures efficiently and facilitate sustainable fire risk management. This study used the MODIS Burned Area Monthly L3 (MCD64A1), Landsat Global Burned Area (BA) products, and MODIS Surface Reflectance 8-Day L3 (MOD09A1) data from 2001 to 2020 to calculate the values of the DFI in the study area before the occurrence of fire. The results showed that: (1) The inversion of the meadow steppe DFI values in the fire area was distributed in the range of 14-26, and the fire rate was the highest in the range of 20-22. The inversion of the typical steppe DFI values in the fire area was distributed in the range of 12-26, and the fire rate was the highest in the range of 16-22. (2) Areas with high fire DFI values included Khalkhgol, Matad, Erdenetsagaan, Bayandun, Gurvanzagal, Dashbalbar in Mongolia, and scattered areas of the Greater Khingan Mountains (forest edge meadow steppe area), East and West Ujumqin Banner, and Xin Barag Right Banner. The highest fire probability of fire occurred during October and April. (3) The DFI values were sensitive to changes in altitude. The results of this study may provide useful information on surface energy balance, grassland carbon storage, soil moisture, grassland health, land desertification, and grazing in the study area, especially for fire risk management.

The number of urban vitality assessment studies is rising continuously, owing to the emergence of geographic data. The current literature focuses primarily on evaluation, rather than implementation, of urban vitality. Hence, a scoping review and research agenda are needed for urban vitality research to be more practical. This study aims to fill the research gap by exploring the content and methods of vitality assessment that can make urban vitality research more compatible with policy, planning, and design practice. We chose the neighborhood scale, which is the most practical initiative unit for vitality enhancement. We discovered that the gaps between the current research and practice primarily lie in the diversity of research subjects, the authenticity and comprehensiveness of vitality measurement, and the multi-domain of impact factor analysis. On this basis, we classified the following expandable aspects: (1) multi-type, multi-dimensional, multi-temporal, and implementation-adaptive vitality evaluation; (2) methods reflecting high-quality social interactions and the perceptions of vulnerable groups; (3) how design and urban management impacts vitality; and (4) the synergistic effects of multiple indicators on vitality. Overall, the research content and methodology presented in this paper can help neighborhood-scale vitality assessment to provide more meaningful insights for policy makers and practitioners.

Yield forecasting can give early warning of food risks and provide solid support for food security planning. Climate change and land use change have direct influence on regional yield and planting area of maize, but few studies have examined their synergistic impact on maize production. In this study, we propose an analysis framework based on the integration of system dynamic (SD), future land use simulation (FLUS) and a statistical crop model to predict future maize yield variation in response to climate change and land use change in a phaeozem region of central Jilin province, China. The results show that the cultivated land is likely to reduce by 862.84 km² from 2030 to 2050. Nevertheless, the total maize yield is expected to increase under all four RCP scenarios due to the promotion of per hectare maize yield. Among the scenarios, RCP4.5 is the most beneficial to maize production, with a doubled total yield in 2050. Notably, the yield gap between different counties will be further widened, which necessitates the differentiated policies of agricultural production and farmland protection, e.g., strengthening cultivated land protection and crop management in low-yield areas, and taking adaptation and mitigation measures to coordinate climate change and production.

The degradation of ecosystem structure and function on the Qinghai-Tibet Plateau is the result of a combination of natural and anthropogenic factors, with landscape change driven by global change and human activities being one of the major ecological challenges facing the region. This study analyzed the spatiotemporal characteristics of ecosystem services (ESs) and landscape patterns in eastern Qinghai province (EQHP) from 2000 to 2018 using multisource datasets and landscape indices. Three ecosystem service bundles (ESBs) were identified using the self-organizing map (SOM), and changes in ecosystem structure and function were analyzed through bundle-landscaped spatial combinations. The study also explored the interactions between ESs and natural and human factors using redundancy analysis (RDA). We revealed an increase in total ecosystem service in the EQHP from 1.59 in 2000 to 1.69 in 2018, with a significant change in landscape patterns driven by the conversion of unused land to grassland in the southwest. Forestland, grassland, and unused land were identified as important to the supply of ESs. In comparison to human activities, natural environmental factors were found to have a stronger impact on changes in ESs, with vegetation, meteorology, soil texture, and landscape composition being the main driving factors. However, the role of driving factors within different ESBs varied significantly. Exploring the response of ecosystem services to changes in landscape patterns can provide valuable insights for achieving sustainable ecological management and contribute to ecological restoration efforts.

Construction land is the leading carrier of human activities such as production and living. Evaluating the construction land suitability (CLS) on the Qinghai-Tibet Plateau (QTP) holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout optimization. However, no relevant studies provide a complete CLS assessment of the QTP. In this study, we developed a model-based CLS evaluation framework coupling of pattern and process to calculate the global CLS on the QTP based on a previously developed CLS evaluation model. Then, using the land-use data of 1990, 2000, 2010, and 2020, we examined the adaptability of existing construction land (ECL) to the CLS assessment result through the adaptability index and vertical gradient index and further analyzed the limitations of maladaptive construction land. Finally, we calculated the potential area of reserve suitable construction land. This article includes four conclusions: (1) The highly suitable, suitable, moderately suitable, marginally suitable, and unsuitable CLS classes cover areas of 0.33×10⁴ km², 10.42×10⁴ km², 18.06× 10⁴ km², 24.12×10⁴ km², and 205.29×10⁴ km², respectively. Only approximately 11% of the study area on the QTP is suitable for large-scale permanent construction land, and approximately 79.50% of the area is unsuitable under current economic and technological conditions. (2) The ECL adaptability index is 85.16%, 85.93%, 85.18%, and 78.01% during 1990-2020, respectively, with an average adaptability index exceeding 80% on the QTP. The ECL distribution generally conforms to construction land suitable space characteristics but with a significant spatial difference. (3) From 1990 to 2020, the maladaptive ECL was dominated by rural settlement land, transport land, and special land, with a rapidly increasing proportion of urban and other construction land. The maladaptive ECL is constrained by both elevation and slope in the southern Qinghai Plateau, the Hengduan Mountains, and the Qilian Mountains. In contrast, elevation is significantly more limiting than slope in the northern Tibet Plateau, the Gangdis Mountains, and the Himalayan Mountains. (4) The potential area of reserve suitable construction land is 12.41×10⁴ km², accounting for 4.81% of the total land area of the QTP, and the per capita area is 9928 m². Regions of Qaidam Basin, Gonghe Basin, and Lhasa-Shannan Valley have the richest and most concentrated land resource of reserve suitable construction land. The research results provide spatial decision support for urban and rural settlement planning and ecological migration on the QTP.

Under the framework of ecological civilisation, the formulation of territorial spatial planning (TSP) and improvement of spatial governance systems are of great practical significance. Since the founding of the People’s Republic of China, land-use planning (LUP) has experienced profound changes, and tremendous research efforts have been made in that field. However, systematic studies on LUP history are scarce. To bridge the existing gap, this study traced back to the emergence of LUP, described its practice stages, and analysed the evolution of its classification system and methods. Further, the three rounds of general LUP practice and the current TSP over the past 40 years of the reform and opening-up have been discussed. The evolution of LUP was found to be closely related to economic development and could be broadly divided into four stages. The development of land-use classification in China has been slow and can be divided into five stages according to the evolution of the land classification system and important historical events. The development of LUP methods can be divided into two stages, before and after 1978. Since the economic reform, China has successively conducted three rounds of general LUP under different institutional and policy backgrounds. Future development should aim to innovate the theories and methods of TSP with Chinese characteristics and promote the study of village planning and the construction of TSP systems to achieve rural revitalisation and ecological civilisation.

Effective soil particle size composition can more realistically reflect the particle size sorting process of erosion. To reveal the individual contributions of rainfall intensity and slope to splash erosion, and to distinguish the enrichment ratio of each size and the critical size in splash, loessial soil collected on the Loess Plateau in May 2019 was tested under different rainfall intensities (60, 84, 108, 132, 156 mm h^-1) and slopes (0°, 5°, 10°, 15°, 20°). The results demonstrated that 99% of splash mass was concentrated in 0-0.4 m. Rainfall intensity was the major factor for splash according to the raindrop generation mode by rainfall simulator nozzles. The contributions of rainfall intensity to splash erosion were 82.72% and 93.24%, respectively in upslope and downslope direction. The mass percentages of effective clay and effective silt were positively correlated with rainfall intensity, while the mass percentages of effective very fine sand and effective fine sand were negatively correlated with rainfall intensity. Opposite to effective very fine sand, the mass percentages of effective clay significantly decreased with increasing distance. Rainfall intensity had significant effects on enrichment ratios, positively for effective clay and effective silt and negatively for effective very fine sand and effective fine sand. The critical effective particle size in splash for loessial soil was 50 μm.

Climate change and human activities have profoundly altered ecosystem services in the Yellow River Basin (YRB) since the Grain for Green project was implemented, but have not been accurately revealed on a year-by-year scale. This study combined the InVEST model to reveal the year-by-year changes in the water-related ecosystem services (WRESs) in YRB during 1990-2020, including water yield, soil conservation and water purification services. The trade-off/synergy of WRESs and impacts of land management measures on WRESs were assessed fully. The results showed that from 1990 to 2020, cropland and barren land were considerably converted to forest and grassland in YRB. WRESs were continuously improved as a result of increase of water yield and reductions of soil export and nitrogen export, at rates of +1.11 mm·yr^-1, -0.23 t·km^-2·yr^-1 and -1.01 kg·km^-2·yr^-1, respectively. We found that in YRB water purification service showed trade-off relationships with soil conservation and water yield services in recent decades, and water yield and soil conservation maintained a synergitic effect. Additionally, the revegetation measures showed a potential of enhancing soil conservation and water purification, but reducing water yield. This study provided a thorough understanding of WRESs dynamics and a valuable reference for the ecological restoration practices.

The two concepts of “liudong renkou (floating population or FP)” and “renkou liudong (mobility of the floating population or MOFP)”, along with relevant data based on these two concepts, have long been used extensively in China’s research and policy making, playing a central role in Chinese studies of migration. Unlike the concepts of “migrant” and “migration” in the international literature, which are focused on people’s spatial mobility, “liudong renkou” and “renkou liudong” are identified and measured by the separation of one’s place of residence from one’s place of household registration (hukou), an approach inconsistent with relevant international practices. By analyzing various census data and data from the China Migrant Dynamic Survey (CMDS), this article examines the validity and reliability of these two concepts and the data based on them in the international context, revealing that they have become increasingly invalid and unreliable for the purpose of measuring migration events since China’s reform and opening up in the late 1970s. The results further demonstrate that these two concepts and the data based on them have become increasingly detached from real migration events and processes. They may become invalid by overestimating the volume of the mobile population, ineffective due to systematic omission of certain mobile populations (such as urban-urban migrants), or misleading as to the changing direction of migration flows. In addition, data on the floating population cannot be used to calculate migration rates and are not comparable in the international context. The concepts of “liudong renkou” and “renkou liudong” and data based on these two concepts may still need to be used in China for a long period of time due to the continuing existence of the hukou system and its roles in the provision of public services, social welfare and social security. However, we argue that concepts, measurements, and methods of data collection in research on migration in China should be gradually shifted to and focused on migrations as spatial events; further, transition data, based on an individual’s residence five years ago and one year ago, should be gradually adopted as the main data source and included in the short form of future censuses; additionally, migration event data based on population registration and administrative records should be used more fully, so that China’s migration research can be conducted on the solid basis of valid and reliable data sources.

Karst depressions are common negative topographic landforms formed by the intense dissolution of soluble rocks and are widely developed in Guizhou province. In this work, an inventory of karst depressions in Guizhou was established, and a total of approximately 256,400 karst depressions were extracted and found to be spatially clustered based on multidistance spatial cluster analysis with Ripley's K function. The kernel density (KD) can transform the position data of the depressions into a smooth trend surface, and five different depression concentration areas were established based on the KD values. The results indicated that the karst depressions are clustered and developed in the south and west of Guizhou, while some areas in the southeast, east and north have poorly developed or no clustering. Additionally, the random forest (RF) model was used to rank the importance of factors affecting the distribution of karst depressions, and the results showed that the influence of lithology on the spatial distribution of karst depressions is absolutely dominant, followed by that of fault tectonics and hydrological conditions. The research results will contribute to the resource investigation of karst depressions and provide theoretical support for resource evaluation and sustainable utilization.

Spatial-temporal scales effects are general among human-nature interactions. However, the laws and mechanisms of the interaction between humans and the environment at different spatial-temporal scales remain to be identified. The Hexi Corridor in Northwest China is located in the eastern section of the Silk Road and is one of the world’s first long-distance cultural exchange centers. Here we present a comprehensive dataset of the Hexi Corridor, including changes in environments, population, wars, famines, settlements, and ancient oases from the Neolithic to the historic period. Results show that humans adapt to climate change on the millennium scale by choosing corresponding production methods. Environmental change, civilization evolution, and dynasty replacement interrelate on the decadal and centennial scales. Social crises are closely linked to extreme weather events on the interannual scale. On the basis of these results, we find similar time scale effects in the world’s major ancient civilizations. We do so by analyzing their processes of civilization evolution.

Megacities serve as global centers for economic, cultural, and high-tech industries. The structural features and population agglomerations are typical traits of urbanization, yet little is known about the morphological features and expansion patterns of megacities worldwide. Here we examined the spatiotemporal variations of urban land in megalopolises from 2000 to 2020 using the Urban Expansion Intensity Differentiation Index. The fractal features and expansion patterns of megacities were analyzed using the Area-Radius Multidimensional Scaling Model. Urban land use efficiency was then evaluated based on the linear relationship between urban land area and population. We found that Southeast Asia and China were the hotspots of urban expansion in megacities from 2000 to 2020, with urban land areas expanding by 3148.32 km² and 5996.26 km², respectively. The morphological features and expansion patterns of megacities exhibited a growing trend towards intensification and compactness, with the average radial dimension increasing from 1.54 to 1.56. The annual decrease in fractal dimensions indicated the integration of inner urban areas. North America and Europe megacities showed a low urban land use efficiency, with a ratio of urban land area to population ranging from 0.89 to 4.11 in 2020. Conversely, South Asia and Africa megacities exhibited a high urban land use efficiency, with the ratios between 0.23 and 0.87. Our results provide information for promoting efficient urban land utilization and sustainable cities. It is proposed to control the scale of urban expansion and to promote balanced development between inner and outer urban areas for achieving resilient and sustainable urban development.

The taiga vegetation in Western Siberia has been seriously threatened by climate warming in recent decades. However, how vegetation in different growing states and climate conditions responds to climate changes differently is still unclear. Here we explore the vegetation activity trends in Western Siberia taiga forests using the annual rate of change in leaf area index (LAI) during 1982-2018 so as to answer two questions: (1) how did climate warming affect taiga vegetation activity in the recent last decades? (2) Did the growing state of taiga forest affect its response to climate warming? Our results revealed that climate warming promoted taiga vegetation activity in Western Siberia before 2000. However, continuous warming caused excessive evapotranspiration and led to decreased vegetation activity after 2000. Moreover, the intensity of vegetation growth response to warming was positively related to canopy height and LAI, indicating that both the positive and negative effects of warming were more significant in taiga forests in better growing state. Since these forests generally have higher productivity and play more important roles in ecosystem functioning (e.g., carbon sink and biodiversity conservation), our results highlight their vulnerability to future climate change that need more research attention.

Cities are the key areas for human beings to achieve sustainable development goals in the future. Estuarine cities are a special type of coastal city in urgent need of a clear definition. This paper proposed that estuarine cities are cities developed on the coast where rivers and oceans meet and defined four connotations, including the intersection of rivers and marine water systems, the coordinated development of land and oceans, the location advantages of connecting rivers and seas, and the important fragility of the ecological environment. We used HydroSHEDS, OSM, GPW, and urban socioeconomic statistics and selected 50 estuarine cities with large rivers as representatives to summarize the main geographical basis and socioeconomic characteristics. Cities are primarily found in low-altitude, flat regions with average annual temperatures that mainly vary from 10°C to 25°C, relatively abundant precipitation, and extensive biological resources. There are substantial variations in the socioeconomic features of estuarine cities. We proposed eight development patterns, including open and inclusive city spirit, high-quality livable cities, high-quality development driven by innovation, integration of internal and external communication with ports and cities, construction of an international financial center, ecological environment protection and restoration, active promotion of cultural tourism, and positive international exchanges.

The increasing frequency of recent droughts has an adverse effect on the ecosystem of the Mongolian Plateau. The growth condition of NPP is considered an indicator of the ecological function. Therefore, identifying the relationship between NPP and drought can assist in the prevention of drought-associated disasters and the conservation of the ecological environment of the Mongolian Plateau. This study used the Carnegie-Ames-Stanford Approach (CASA) model to simulate the NPP capacity of the Mongolian Plateau between 1982 and 2015, as well as drought indicators (drought probability, vulnerability, and risk) to explore the drought risk of NPP. The findings pointed to an overall increase in NPP with regional variances; however, the NPP rate in Inner Mongolia was considerably higher than that in Mongolia. The standardized precipitation evapotranspiration index (SPEI) showed an overall downward trend, with Inner Mongolia experiencing a substantially lower rate of decline than Mongolia. The areas most likely to experience drought were primarily in the center and north while the areas with the highest drought vulnerability were primarily in the northeast, center, and southeast. Mongolia showed a higher probability of drought compared to Inner Mongolia. Drought-prone regions of the Mongolian Plateau increased during the 21st century while drought-vulnerable areas increased and shifted from north to south. Alpine grasslands and coniferous forests were least vulnerable to drought, while other vegetation types experienced temporal variation. In the 21st century, the primary determinants of drought risk shifted from precipitation and the normalized difference vegetation index (NDVI) to temperature and relative humidity.

The leaf area index (LAI) shows a significant increasing trend from global to regional scales, which is known as greening. Greening will further enhance photosynthesis, but it is unclear whether the contribution of greening has exceeded the CO₂ fertilization effect and become the dominant factor in the gross primary productivity (GPP) variation. We took the Yangtze River Delta (YRD) of China, where cropland and natural vegetation are significantly greening, as an example. Based on the boreal ecosystem productivity simulator (BEPS) and Revised-EC-LUE models, the GPP in the YRD from 2001 to 2020 was simulated, and attribution analysis of the interannual variation in GPP was performed. In addition, the reliability of the GPP simulated by the dynamic global vegetation model (DGVM) in the area was further investigated. The research results showed that GPP in the YRD had three significant characteristics consistent with LAI: (1) GPP showed a significant increasing trend; (2) the multiyear mean and trend of natural vegetation GPP were higher than those of cropland GPP; and (3) cropland GPP showed double-high peak characteristics. The BEPS and Revised-EC-LUE models agreed that the effect of LAI variation (4.29 Tg C yr^-1 for BEPS and 2.73 Tg C yr^-1 for the Revised-EC-LUE model) determined the interannual variation in GPP, which was much higher than the CO₂ fertilization effect (2.29 Tg C yr^-1 for BEPS and 0.67 Tg C yr^-1 for the Revised-EC-LUE model). The GPP simulated by the 7 DGVMs showed a huge inconsistency with the GPP estimated by remote sensing models. The deviation of LAI simulated by DGVM might be a potential cause for this phenomenon. Our study highlights that in significant greening areas, LAI has dominated GPP variation, both spatially and temporally, and DGVM can correctly simulate GPP only if it accurately simulates LAI variation.

Land subsidence is a geohazard phenomenon caused by the lowering of land elevation due to the compression of the sinking land soil body, thus creating an excessive constraint on the safe construction and sustainable development of cities. The use of accurate and efficient means for land subsidence prediction is of remarkable importance for preventing land subsidence and ensuring urban safety. Although the current time-series prediction method can accomplish relatively high accuracy, the predicted settlement points are independent of each other, and the existence of spatial dependence in the data itself is lost. In order to unlock this problem, a spatial convolutional long short-term memory neural network (ConvLSTM) based on the spatio-temporal prediction method for land subsidence is constructed. To this end, a cloud platform is employed to obtain a long time series deformation dataset from May 2017 to November 2021 in the understudied area. A convolutional structure to extract spatial features is utilized in the proposed model, and an LSTM structure is linked to the model for time-series prediction to achieve unified modeling of temporal and spatial correlation, thereby rationally predicting the land subsidence progress trend and distribution. The experimental results reveal that the prediction results of the ConvLSTM model are more accurate than those of the LSTM in about 62% of the understudied area, and the overall mean absolute error (MAE) is reduced by about 7%. The achieved results exhibit better prediction in the subsidence center region, and the spatial distribution characteristics of the subsidence data are effectively captured. The present prediction results are more consistent with the distribution of real subsidence and could provide more accurate and reasonable scientific references for subsidence prevention and control in the Beijing-Tianjin-Hebei region.

Glaciers in the Tianshan Mountains are an essential water resource in Central Asia, and it is necessary to identify their variations at large spatial scales with high resolution. We combined optical and SAR images, based on several machine learning algorithms and ERA-5 land data provided by Google Earth Engine, to map and explore the glacier distribution and changes in the Tianshan in 2001, 2011, and 2021. Random forest was the best performing classifier, and the overall glacier area retreat rate showed acceleration from 0.87%/a to 1.49%/a, while among the sub-regions, Dzhungarsky Alatau, Central and Northern/Western Tianshan, and Eastern Tianshan showed a slower, stable, and sharp increase rates after 2011, respectively. Glacier retreat was more severe in the mountain periphery, low plains and valleys, with more area lost near the glacier equilibrium line. The sustained increase in summer temperatures was the primary driver of accelerated glacier retreat. Our work demonstrates the advantage and reliability of fusing multisource images to map glacier distributions with high spatial and temporal resolutions using Google Earth Engine. Its high recognition accuracy helped to conduct more accurate and time-continuous glacier change studies for the study area.

The current suitability evaluation methods for land resources human activity in China suffer from theoretical deficiencies related to fundamental data accuracy, elevation and slope classification, and suitability class judgment. Empirical application of these methods is also hindered by excessive evaluation indicators, data acquisition difficulties, and limited applicability to high altitude regions. To address these issues, this paper proposes a technical evaluation framework for the Qinghai-Tibet Plateau (QTP) that employs selected key parameters varying with elevation and slope to establish grid-scale evaluation models for construction land suitability (CLS) and arable land suitability (ALS). A generalized algorithm is then proposed for key parameters such as air density, air temperature, slope suitability for construction, and soil erosion resistance of sloping arable land. Empirical research is conducted using Milin County in southeast Tibet as a case study, with interval measurements of 100 m in elevation and 1° in slope. The evaluation model is tested using grid accuracies of 30 m, 50 m, 100 m, 250 m, 500 m, and 1000 m. The results reveal that: Firstly, the CLS and ALS can be categorized into five classes: highly suitable, suitable, moderately suitable, marginally suitable, and unsuitable, with varying area ratios under different grid accuracies. Secondly, existing construction lands in Milin County are mainly distributed in suitable, highly suitable, and moderately suitable CLS classes, accounting for over 94% of the total area studied under different grid accuracies. While arable land is mainly distributed in suitable, highly suitable, and moderately suitable ALS classes, accounting for over 96%. Thirdly, the empirical research in Milin County indicates that the evaluation method, quantitative model, and parameters algorithm for evaluating human activity suitability of land resources on the QTP are feasible and applicable, with a recommended grid accuracy within 100 m and a maximum of 250 m. Fourthly, the paper establishes a correspondence between land suitability (including construction land and arable land) and topographic factors (elevation and slope) that can be applied to the QTP. Finally, some professional defects in the evaluation methods of available land resources in Major Function Zoning and “Double Evaluations” of Territorial Spatial Planning in China when applied to the QTP are identified.