Danxia geomorphology originates from China. This paper studies the spatial distribution and differences in characteristics of Danxia landforms. Based on relevant research and investigations, three congregated areas of Danxia landform in China are discussed in this paper. They are the southeast area (including Jiangxi, Fujian, Zhejiang, Hunan and Guangxi provinces), the southwest area (the transitional zone of Yunnan-Guizhou Plateau and Sichuan Basin) and the northwest area (including Longshan mountain and along the banks of the Huanghe River and its anabranches). Not only the conditions of geology and geography of the three areas but also the differences of Danxia landforms of the three areas are analyzed. The Danxia landscape, characterized by upright-shaped peaks, Danxia mesa, stone wall, cave and vertical cave, "Danxia natural bridge", "a narrow strip of sky" and so on, often presents in the southeast area. The landscape of southwest area is characterized by Danxia escarpment faces and waterfalls. In the northwest area, the Danxia landscape has the traits of arid areas simultaneously, for example, mud-coating type, columniation type, board type, moreover, it is greatly different between these environmental factors such as the microclimate, water, wind, and the loess cover. Finally it explores the causes which lead differences in landform and also explains the landform formation process and its mechanism with reference to the rates of crustal uplift, the tectonic red-basin, and the external processes including working of running water, weathering, biogenic, gravity in each area of Danxia Landforms in China.

Based on dynastic period division and AMS¹⁴C dating performed on the sedimen-tary layers at Zhongba and Yuxi sites, and also the analysis of Na, Ca and Mg of 201 sedi-mentary samples from Zhongba site and that of Ca and Na in 47 sedimentary samples from Yuxi by using an inductively coupled plasma–mass spectrometry (ICP), we found that there were 35 time periods when the contents of Ca and Na were reversely correlated, i.e. when-ever the content of Ca was the highest, the content of Na was the lowest, and vice versa. Among them, there were 21 time periods when the content of Ca was the highest, and Na was the lowest, indicating that there were about 21 prosperous periods of ancient salt pro-duction at Zhongba site since 3000BC. Other 14 time periods with the peak values of Na while the low values of Ca indicate 14 declined periods of salt production at Zhongba site since 3000BC. The conclusion obtained from the reverse relationship between Ca and Na contents in this paper is consistent with that “the salt production at Zhongba site started in the new stone age, developed in the Xia and Shang dynasties, reached at the heyday in periods from the Western Zhou to the Han Dynasties, maintained stable to develop in the Tang and the Song dynasties, and gradually declined after the Song Dynasty because the sea salt were conveyed into Sichuan region, however, still had production in the 1970s–1980s”, educed from archeological exploration. All the above mentioned results indicate that there is a re-verse relationship obviously between the contents of Na and Ca in sediments at Zhongba site for ancient salt production, which can

Different government departments and researchers have paid considerable attention at various levels to improving the eco-environment in ecologically fragile areas. Over the past decade, large numbers of people have emigrated from rural areas as a result of the rapid urbanization in Chinese society. The question then remains: to what extent does this migration affect the regional vegetation greenness in the areas that people have moved from? Based on normalized difference vegetation index (NDVI) data with a resolution of 1 km, as well as meteorological data and socio-economic data from 2000 to 2010 in Inner Mongolia, the spatio-temporal variation of vegetation greenness in the study area was analyzed via trend analysis and significance test methods. The contributions of human activities and natural factors to the variation of vegetation conditions during this period were also quantitatively tested and verified, using a multi-regression analysis method. We found that: (1) the vegetation greenness of the study area increased by 10.1% during 2000-2010. More than 28% of the vegetation greenness increased significantly, and only about 2% decreased evidently during the study period. (2) The area with significant degradation showed a banded distribution at the northern edge of the agro-pastoral ecotone in central Inner Mongolia. This indicates that the eco-environment is still fragile in this area, which should be paid close attention. The area where vegetation greenness significantly improved showed a concentrated distribution in the southeast and west of Inner Mongolia. (3) The effect of agricultural labor on vegetation greenness exceeded those due to natural factors (i.e. precipitation and temperature). The emigration of agricultural labor improved the regional vegetation greenness significantly.

The Yangtze River Delta (YRD) is a region in China with a serious contradiction between economic growth and environmental pollution. Exploring the spatiotemporal effects and influencing factors of air pollution in the region is highly important for formulating policies to promote the high-quality development of urban industries. This study uses the spatial Durbin model (SDM) to analyze the local direct and spatial spillover effects of industrial transformation on air pollution and quantifies the contribution of each factor. From 2008 to 2018, there was a significant spatial agglomeration of industrial sulfur dioxide emissions (ISDE) in the YRD, and every 1% increase in ISDE led to a synchronous increase of 0.603% in the ISDE in adjacent cities. The industrial scale index (ISCI) and industrial structure index (ISTI), as the core factors of industrial transformation, significantly affect the emissions of sulfur dioxide in the YRD, and the elastic coefficients are 0.677 and -0.368, respectively. The order of the direct effect of the explanatory variables on local ISDE is ISCI>ISTI>foreign direct investment (FDI)>enterprise technological innovation (ETI)>environmental regulation (ER)> per capita GDP (PGDP). Similarly, the order of the spatial spillover effect of all variables on ISDE in adjacent cities is ISCI>PGDP>FDI>ETI>ISTI>ER, and the coefficients of the ISCI and ISTI are 1.531 and 0.113, respectively. This study contributes to the existing research that verifies the environmental Kuznets curve in the YRD, denies the pollution heaven hypothesis, indicates the Porter hypothesis, and provides empirical evidence for the formation mechanism of regional environmental pollution from a spatial spillover perspective.

This paper reviews the process of transportation construction in China and investigates the developmental and spatial characteristics of transportation patterns. The principles of transportation evolution including stages, structures and orders are systematically analyzed. The investigation shows that China’s transportation construction mode has upgraded from investment-driven scale expansion to quality improvement driven by efficiency and promotion. The rapid growth and development of transportation networks has significantly influenced economic and social activities in time and space. The resulting spatial convergence and dominance have improved distribution, promoting development of the socioeconomic structure. Regional development that has traditionally been based on corridors has changed into a networked mode centered on cities and metropolitan areas. The transportation pattern follows evolutionary principles. China has been moving from a hierarchical structure to a cascade structure. Simultaneously, the socioeconomic pattern has changed from an axis to a hub-and-spoke structure with a preliminary ordered network. As transportation networks grow, China’s functional spatial structure and ordered network will gradually become stabilized and balanced.

Based on the data up to 1999 from hydroclimatological departments, this paper analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipitation D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0 ^oC temperature anomaly over China marks, perhaps, the important transition period in which the environment becomes more vulnerable than before.The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.

Forest vegetation carbon patterns are significant for evaluating carbon emission and accumulation. Many methods were used to simulate patterns of forest vegetation carbon stock in previous studies, however, uncertainty apparently existed between results of different methods, even estimates of same method in different studies. Three previous methods, including Atmosphere-vegetation interaction model 2 (AVIM2), Kriging, Satellite-data Based Approach (SBA), and a new method, High Accuracy Surface Modeling (HASM), were used to simulate forest vegetation carbon stock patterns in Jiangxi Province in China. Cross-validation was used to evaluate methods. The uncertainty and applicability of the four methods on provincial scale were analyzed and discussed. The results showed that HASM had the highest accuracy, which improved by 50.66%, 33.37% and 28.58%, compared with AVIM2, Kriging and SBA, respectively. Uncertainty of simulation of forest biomass carbon stock was mainly derived from modeling error, sampling error and statistical error of forest area. Total forest carbon stock, carbon density and forest area of Jiangxi were 288.62 Tg, 3.06 kg/m² and 94.32×10⁹ m² simulated by HASM, respectively.

Based on the radiosonde data observed at 14 stations in Southwest China from 1960 to 2010, as well as the corresponding surface air temperature, the long-term change of free-air 0℃ isotherm height in Southwest China and the relationships between surface air temperature and 0℃ isotherm height are discussed. The results indicated that the spatial distribution of 0℃ isotherm height is generally related with latitude, but the huge massif or plateau may complicate the latitude pattern. The two main regimes influencing the spatial patterns of 0℃ isotherm height in Southwest China are latitude and huge massif. The annual 0℃ isotherm height has increased by 35 m per decade in the recent decades, which is statistically significant at the 0.001 level. Generally, the increasing trend can be examined for each seasonal series, especially in winter (53 m per decade). The diversity of trend magnitudes for annual and seasonal series can also be detected at a spatial view, but generally 0℃ isotherm height correlated well with surface air temperature.

In order to estimate the present-day pollution levels in the ecosystem of the Se-lenga River Delta and to monitor the changes caused by the discharge of household refuse and industrial wastes, as well as the functioning of the agricultural and stock farming, a comprehensive study of the water and bottom sediments in the main branches of the Selenga River Delta was carried out. This study has determined the concentrations of heavy metals in river water and bottom sediments in its delta.

As two rising great powers, China and India have undergone similar development processes, but they also exhibit significant differences in development paths and patterns. The significant differences in political systems, economic systems, and developmental environment between the two countries have attracted great attention from scholars. This research focuses on the regional differences and spatial evolution processes in urbanization and urban systems between the two countries from a geographical perspective. Based on the demographic censuses of both countries and the urban population data from the United Nations, this paper systematically compared and analyzed the spatial characteristics of urbanization and urban systems in China and India using various methods including spatial analysis, parameter estimation, and nonparametric estimation. The results indicate that: (1) Since the 1990s, the regional differences in urbanization in China have transformed from south-north differences to coastal-inland differences, whereas the north-south differences in India have been stable. (2) In recent years, the correlation between population density and urbanization rate kept increasing in China, while such correlation has been decreasing in India. (3) The economic reform posed significantly different effects on the spatial evolution of the urban systems in the two countries. The economic reform changed the major driving force for urban development in China from geographical and historical factors to the spatial structure of the economic system. However, in India, the driving forces for urban development have always been geographical and historical factors, and the economic reform even decreased the effect of the spatial structure of the economic system on urban development.

The ice shelves in the northern Antarctic Peninsula are highly sensitive to variations of temperature and have therefore served as indicators of global warming. In this study, we estimate the velocities of the ice shelves in the northern Antarctic Peninsula using co-registration of optically sensed images and correlation module (COSI-Corr) in the Environment for Visualizing Images (ENVI) based on Moderate Resolution Imaging Spectroradiometer (MODIS) images during 2000-2012, from which we conclude that the ice ?ow directions generally match the peninsulas pattern and the crevasse, ice flows mainly eastward into the Weddell Sea. The spatial pattern of velocity field exhibits an increasing trend from the western grounding line to the maximum at the middle part of the ice shelf front on Larsen C with a velocity of approximately 700 ma^-1, and the velocity field shows relatively higher values in its southerly neighboring ice shelf (e.g. Smith Inlet). Additionally, ice ?ows are relatively quicker in the outer part of the ice shelf than in the inner parts. Temporal changes in surface velocities show a continuous increase from 2000 to 2012. It is worth noting that, the acceleration rate during 2000-2009 is relatively higher than that during 2009-2012, while the ice movement on the southern Larsen C and Smith Inlet shows a deceleration from 2009 to 2012.

The rapid development of high-speed rail (HSR) is influencing regional development, regional structure, commuting, and regional integration. East Asia is the region with the world’s first and largest current operating and planned HSR network. In this paper, we examine the evolutionary mechanism and impacts on the transport circle and accessibility of HSR in East Asia. The results indicate that the HSR network first follows a “core-core” model and then forms a corridor in Japan, South Korea, and China Taiwan, but then forms a complete network in China Mainland. The current operating HSR lines are mostly distributed in regions with developed economies and dense populations, and more than half of the population and GDP in China can be served by HSR within 1 hour’s travel time. The planned HSR network will expand to the western region of China and Japan and the southern region of South Korea. The development of the current operating and planned HSR network considerably enlarges the transport circle of core cities, especially cities along trunk HSR lines. This 1 h transport circle of core cities has formed continuous regions in the Yangtze River Delta, the Pearl River Delta, Tokyo, Seoul, and along trunk HSR lines. The HSR network will bring about substantial improvement in accessiblity, but also increase the inequality of nodal accessibility in China Mainland. Spatially, the spatial patterns of the weighted shortest travel time of cities in China Mainland, Japan, and South Korea all present the “core-peripheral structure”, taking Zhengzhou, Tokyo, and Seoul, respectively, as core cities, and cities located along the trunk HSR lines gain large improvement in accessibility.

Exploring the spatio-temporal dynamics of poverty is important for research on sustainable poverty reduction in China. Based on the perspective of development geography, this paper proposes a panel vector autoregressive (PVAR) model that combines the human development approach with the global indicator framework for Sustainable Development Goals (SDGs) to identify the poverty-causing and the poverty-reducing factors in China. The aim is to measure the multidimensional poverty index (MPI) of China’s provinces from 2007 to 2017, and use the exploratory spatio-temporal data analysis (ESTDA) method to reveal the characteristics of the spatio-temporal dynamics of multidimensional poverty. The results show the following: (1) The poverty-causing factors in China include the high social gross dependency ratio and crop-to-disaster ratio, and the poverty-reducing factors include the high per capita GDP, per capita social security expenditure, per capita public health expenditure, number of hospitals per 10,000 people, rate of participation in the new rural cooperative medical scheme, vegetation coverage, per capita education expenditure, number of universities, per capita research and development (R&D) expenditure, and funding per capita for cultural undertakings. (2) From 2007 to 2017, provincial income poverty (IP), health poverty (HP), cultural poverty (CP), and multidimensional poverty have been significantly reduced in China, and the overall national poverty has dropped by 5.67% annually. there is a differentiation in poverty along different dimensions in certain provinces. (3) During the study period, the local spatial pattern of multidimensional poverty between provinces showed strong spatial dynamics, and a trend of increase from the eastern to the central and western regions was noted. The MPI among provinces exhibited a strong spatial dependence over time to form a pattern of decrease from northwestern and northeastern China to the surrounding areas. (4) The spatio-temporal networks of multidimensional poverty in adjacent provinces were mainly negatively correlated, with only Shaanxi and Henan, Shaanxi and Ningxia, Qinghai and Gansu, Hubei and Anhui, Sichuan and Guizhou, and Hainan and Guangdong forming spatially strong cooperative poverty reduction relationships. These results have important reference value for the implementation of China’s poverty alleviation strategy.

Given the importance of waterway depths in river development, the effects of the evolution of bars and troughs on waterway expansion play an important role in river management and water depth conservation. This study aims to expand the waterway dimensions of the Jingjiang Reach of the Yangtze River. To achieve this objective, determining the relationship between river evolution processes and the potential for waterway depth improvement and navigation hindrances is vital. Therefore, the sedimentation, hydrological, and terrain data of the Jingjiang Reach from 1955 to 2020 are analysed to elucidate the above-mentioned relationship. Since the commissioning of the Three Gorges Dam, the scouring of the low-flow channel has accounted for 90%-95% of all scouring in the Jingjiang Reach. Furthermore, the central bars and beaches have shrunk by 9.4% and 24.9%, respectively, and 18.3% overall. Considering the bed scouring and waterway regulation projects in the Jingjiang Reach, we investigated the continuity of a 4.5 m × 200 m × 1050 m (depth × width × bend radius) waterway along the Jingjiang Reach, and find that navigation-hindering channels account for over 5.3% of the waterway length. Furthermore, part of the Jingjiang Reach is an important nature reserve and shelters numerous water-related facilities, which inhibits the implementation of waterway deepening projects. The findings of this study demonstrate that numerous challenges are associated with increasing the waterway depths of the Jingjiang Reach.

The robustness of cargo ship transportation networks is essential to the stability of the world trade system. The current research mainly focuses on the coarse-grained, holistic cargo ship transportation network while ignoring the structural diversity of different sub-networks. In this paper, we evaluate the robustness of the global cargo ship transportation network based on the most recent Automatic Identification System (AIS) data available. First, we subdivide three typical cargo ship transportation networks (i.e., oil tanker, container ship and bulk carrier) from the original cargo ship transportation network. Then, we design statistical indices based on complex network theory and employ four attack strategies, including random attack and three intentional attacks (i.e., degree-based attack, betweenness-based attack and flux-based attack) to evaluate the robustness of the three typical cargo ship transportation networks. Finally, we compare the integrity of the remaining ports of the network when a small proportion of ports lose their function. The results show that 1) compared with the holistic cargo ship transportation network, the fine-grain-based cargo ship transportation networks can fully reflect the pattern and process of global cargo transportation; 2) different cargo ship networks behave heterogeneously in terms of their robustness, with the container network being the weakest and the bulk carrier network being the strongest; and 3) small-scale intentional attacks may have significant influence on the integrity of the container network but a minor impact on the bulk carrier and oil tanker transportation networks. These conclusions can help improve the decision support capabilities in maritime transportation planning and emergency response and facilitate the establishment of a more reliable maritime transportation system.

The simulation of intercity population mobility helps to deepen the understanding of intercity population mobility and its underlying laws, which has great importance for epidemic prevention and control, social management, and even urban planning. There are many factors that affect intercity population mobility, such as socioeconomic attributes, geographical distance, and industrial structure. The complexity of the coupling among these factors makes it difficult to simulate intercity population mobility. To address this issue, we propose a novel method named the quantum harmonic oscillator model for simulation of intercity population mobility (QHO-IPM). QHO-IPM describes the intercity population mobility as being affected by coupled driving factors that work as a multioscillator-coupled quantum harmonic oscillator system, which is further transformed by the oscillation process of an oscillator, namely, the breaking point of intercity population mobility. The intercity population mobility among seven cities in the Beijing-Tianjin-Hebei region and its surrounding region is taken as an example for verifying the QHO-IPM. The experimental results show that (1) compared with the reference methods (the autoregressive integrated moving average (ARIMA) and long and short-term memory (LSTM) models), the QHO-IPM achieves better simulation performance regarding intercity population mobility in terms of both overall trend and mutation. (2) The simulation error in the QHO-IPM for different-level intercity population mobility is small and stable, which illustrates the weak sensitivity of the QHO-IPM to intercity population mobility under different structures. (3) The discussion regarding the influence degree of different driving factors reveals the significant “one dominant and multiple auxiliary” factor pattern of driving factors on intercity population mobility in the study area. The proposed method has the potential to provide valuable support for understanding intercity population mobility laws and related decision-making on intercity population mobility control.

Water vapour and CO₂ fluxes were measured by the eddy-covariance technique above a mixed needle and broad-leaved forest with affiliated meteorological measurements in Changbai Mountain as part of China's FLUX projects since late August in 2002. Net water vapour exchange and environmental control over the forest were examined from September 1 to October 31 in 2002. To quantify the seasonal dynamics, the transition period was separated into leafed, leaf falling and leafless stages according to the development of leaf area. The results showed that (a) seasonal variation of water vapour exchange was mainly controlled by net radiation (Rn) which could account for 78.5%, 63.4% and 56.6% for leafed, leaf falling and leafless stages, respectively, while other environmental factors' effects varied evidently; (b) magnitude of water vapour flux decreased remarkably during autumn and daily mean of water vapour exchange was 24.2 mg m^-2 s^-1 (100%), 14.8 mg m^-2 s^-1 (61.2%) and 10.3 mg m^-2 s^-1 (42.6%) for leafed, leaf falling and leafless stage, respectively; and (c) the budget of water vapour exchange during autumn was estimated to be 87.1 kg H₂O m^-2, with a mean of 1427.2 g H₂O d^-1 varying markedly from 3104.0 to 227.5 g H₂O m^-2 d^-1.

Studies investigating innovation networks shaped by large innovative enterprises (LI-ENTs), which play a very important role in intercity diffusion of technology and knowledge, are rather thin on the ground. Using location information of LI-ENTs in China, we performed a headquarter-branch analysis to generate intercity innovation linkages and analyzed the patterns and dynamics of the generated network of knowledge diffusion. Although the network covers 353 cities across China, its spatial distribution is extremely uneven, with a few cities and city-dyads dominating the structure of the network. Furthermore, intercity linkages of innovation within and of urban agglomerations, as well as their central cities, stand out. With regard to network dynamics, the economic development level, innovation ability, and administrative level of cities, as well as the geographical, institutional, and technological proximity between cities are all found to have a positive impact on intercity linkages of innovations, whilst the impact of FDI on the national distribution of Chinese innovative enterprises is negative. Most importantly, the status of cities within the urban agglomeration exerts a significant positive effect in relation to the innovative enterprises’ expansions, which reflects that the top-down forces of government and the bottom-up forces of market function together.

The rapid progress of China’s industrialization has been manifested in space as the formation and evolution of a series of industrial bases. Employing data from the years 1985, 2001 and 2010, this paper carries out differentiation, screening, and categorization of industrial bases in China. It then analyses the evolutional characteristics of these industrial bases and explores different paths of growth according to their scale or types, and summarizes the general pattern for their formation and evolution. The results of this study indicate that China’s industrial bases as a whole have gone through three spatial stages since the founding of the PRC in 1949: decentralized development before reform and opening up in 1978, gradual concentration in eastern coastal regions during the early period of reform and opening up, and balanced and diversified development since the beginning of the 21st century. By 2010, China had a total of 251 industrial bases and had thereby established the overall spatial map of its industrialization. As industrial bases expand in scale, their industrial structures develop from homogenization to diversification, and then again from diversification to competitive optimization. Leading industries in the vast majority of industrial bases constantly evolve along the track of light industries, basic materials industries, and advanced manufacturing industries. Meanwhile, the key factors in their evolution and development transition from traditional factors of production like resources and labor to new ones like capital and information, but there are significant differences in terms of influencing factors and growth paths between large, medium, and small bases. Small industrial bases primarily rely on natural resources to maintain development through a single leading industry, medium industrial bases gradually become more comprehensive in their industrial compositions, and large industrial bases evolve in the direction of a combination of basic materials industries and equipment manufacturing industries.

As one of the areas with numerous lakes on the Tibetan Plateau, the Hoh Xil region plays an extremely important role in the fragile plateau eco-environment. Based on topographic maps in the 1970s and Landsat TM/ETM+ remote sensing images in the 1990s and the period from 2000 to 2011, the data of 83 lakes with an area above 10 km² each were obtained by digitization method and artificial visual interpretation technology, and the causes for lake variations were also analyzed. Some conclusions can be drawn as follows. (1) From the 1970s to 2011, the lakes in the Hoh Xil region firstly shrank and then expanded. In particular, the area of lakes generally decreased during the 1970s-1990s. Then the lakes expanded from the 1990s to 2000 and the area was slightly higher than that in the 1970s. The area of lakes dramatically increased after 2000. (2) From 2000 to 2011, the lakes with different area ranks in the Hoh Xil region showed an overall expansion trend. Meanwhile, some regional differences were also discovered. Most of the lakes expanded and were widely distributed in the northern, central and western parts of the region. Some lakes were merged together or overflowed due to their rapid expansion. A small number of lakes with the trend of area decrease or strong fluctuation were scattered in the central and southern parts of the study area. And their variations were related to their own supply conditions or hydraulic connection with the downstream lakes or rivers. (3) The increase in precipitation was the dominant factor resulting in the expansion of lakes in the Hoh Xil region. The secondary factor was the increase in meltwater from glaciers and frozen soil due to climate warming.

The impact of reservoirs on downstream river channel change has been a scientific issue in fluvial geomorphology during the last few decades. However, it is still a difficult issue as to how to express quantitatively the channel adjustment in the Inner Mongolian reach of the Yellow River induced by the joint operation of upstream reservoirs. Based on the shape parameters of channel cross-sections at four gauging stations in this river reach over a flooding season in two periods, 1978-1982 and 2008-2012, the present work investigated the channel changes in terms of shape parameter change rate under the same controlling water level in each flooding season at the channel cross-sections. Results showed that most of the change rates of the parameters evidently increased over a flooding season in both periods. However, the change rate of each parameter at the cross-sections decreased evidently in the latter period, compared with the former period. At the same time, the distribution pattern of the change rate of the shape parameters along the cross-sections thus changed from a convex curve in the former period to an S-shaped curve in the latter period. The obvious decrease of the change rates is related to the joint operation of the Liujiaxia and Longyangxia reservoirs. The reservoirs stored a large volume of water and decreased the peak discharge and maximum velocity in the flooding season; as a result, the erosion ability of the flood decreased accordingly. With the joint operation of the large reservoirs, the Inner Mongolian channel shrunk markedly. Therefore, the channel will present the possibility of an extreme flood in the future. Consequently, it is reasonable to adjust the function of the reservoirs in future. The total water and sediment discharges and the peak discharge in flooding seasons should be effectively controlled. Continuous shrinkage of the channel can thus be avoided and it can be ready for a potential extreme flood.

City growth patterns are attracting more attention in urban geography studies. This paper examines how cities develop and grow in the upper tail of size distribution in a large-scale economy based on a theoretical model under new economic geography framework and the empirical evidence from the US. The results show that cities grow in a sequential pattern. Cities with the best economic conditions are the first to grow fastest until they reach a critical size, then their growth rates slow down and the smaller cities farther down in the urban hierarchy become the fastest-growing ones in sequence. This paper also reveals three related features of urban system. First, the city size distribution evolves from low-level balanced to primate and finally high-level balanced pattern in an inverted U-shaped path. Second, there exist persistent discontinuities, or gaps, between city size classes. Third, city size in the upper tail exhibits conditional convergence characteristics. This paper could not only contribute to enhancing the understanding of urbanization process and city size distribution dynamics, but also be widely used in making effective policies and scientific urban planning.

The question of how to generate maximum socio-economic benefits while at the same time minimizing input from urban land resources lies at the core of regional ecological civilization construction. We apply stochastic frontier analysis (SFA) in this study to municipal input-output data for the period between 2005 and 2014 to evaluate the urbanization efficiency of 110 cities within the Yangtze River Economic Belt (YREB) and then further assess the spatial association characteristics of these values. The results of this study initially reveal that the urbanization efficiency of the YREB increased from 0.34 to 0.53 between 2005 and 2014, a significant growth at a cumulative rate of 54.07%. Data show that the efficiency growth rate of cities within the upper reaches of the Yangtze River has been faster than that of their counterparts in the middle and lower reaches, and that there is also a great deal of additional potential for growth in urbanization efficiency across the whole area. Secondly, results show that urbanization efficiency conforms to a “bar-like” distribution across the whole area, gradually decreasing from the east to the west. This trend highlights great intra-provincial differences, but also striking inter-provincial variation within the upper, middle, and lower reaches of the Yangtze River. The total urbanization efficiency of cities within the lower reaches of the river has been the highest, followed successively by those within the middle and upper reaches. Finally, values for Moran’s I within this area remained higher than zero over the study period and have increased annually; this result indicates a positive spatial correlation between the urbanization efficiency of cities and annual increments in agglomeration level. Our use of the local indicators of spatial association (LISA) statistic has enabled us to quantify characteristics of “small agglomeration and large dispersion”. Thus, “high- high” (H-H) agglomeration areas can be seen to have spread outwards from around Zhejiang Province and the city of Shanghai, while areas characterized by “low-low” (L-L) patterns are mainly concentrated in the north of Anhui Province and in Sichuan Province. The framework and results of this research are of considerable significance to our understanding of both land use sustainability and balanced development.

Using the Integrated Biosphere Simulator, a dynamic vegetation model, this study initially simulated the net primary productivity (NPP) dynamics of China’s potential vegetation in the past 55 years (1961-2015) and in the future 35 years (2016-2050). Then, taking the NPP of the potential vegetation in average climate conditions during 1986-2005 as the basis for evaluation, this study examined whether the potential vegetation adapts to climate change or not. Meanwhile, the degree of inadaptability was evaluated. Finally, the NPP vulnerability of the potential vegetation was evaluated by synthesizing the frequency and degrees of inadaptability to climate change. In the past 55 years, the NPP of desert ecosystems in the south of the Tianshan Mountains and grassland ecosystems in the north of China and in western Tibetan Plateau was prone to the effect of climate change. The NPP of most forest ecosystems was not prone to the influence of climate change. The low NPP vulnerability to climate change of the evergreen broad-leaved and coniferous forests was observed. Furthermore, the NPP of the desert ecosystems in the north of the Tianshan Mountains and grassland ecosystems in the central and eastern Tibetan Plateau also had low vulnerability to climate change. In the next 35 years, the NPP vulnerability to climate change would reduce the forest-steppe in the Songliao Plain, the deciduous broad-leaved forests in the warm temperate zone, and the alpine steppe in the central and western Tibetan Plateau. The NPP vulnerability would significantly increase of the temperate desert in the Junggar Basin and the alpine desert in the Kunlun Mountains. The NPP vulnerability of the subtropical evergreen broad-leaved forests would also increase. The area of the regions with increased vulnerability would account for 27.5% of China.

An evolutionary model of sedimentary environments since late Marine Isotope Stage 3 (late MIS 3, i.e., ca. 39 cal ka BP) along the middle Jiangsu coast is presented based upon a reinterpretation of core 07SR01, new correlations between adjacent published cores, and shallow seismic profiles recovered in the Xiyang tidal channel and adjacent northern sea areas. Geomorphology, sedimentology, radiocarbon dating and seismic and sequence stratigraphy are combined to confirm that environmental changes since late MIS 3 in the study area were controlled primarily by sea-level fluctuations, sediment discharge of paleo-rivers into the South Yellow Sea (SYS), and minor tectonic subsidence, all of which impacted the progression of regional geomorphic and sedimentary environments (i.e., coastal barrier island, freshwater lacustrine swamp, river floodplain, coastal marsh, tidal sand ridge, and tidal channel). This resulted in the formation of a fifth-order sequence stratigraphy, comprised of the parasequence of the late stage of the last interstadial (Para-Sq2), including the highstand and forced regressive wedge system tracts (HST and FRWST), and the parasequence of the postglacial period (Para-Sq1), including the transgressive and highstand system tracts (TST and HST). The tidal sand ridges likely began to develop during the postglacial transgression as sea-level rise covered the middle Jiangsu coast at ca. 9.0 cal ka BP. These initially submerged tidal sand ridges were constantly migrating until the southward migration of the Yellow River mouth to the northern Jiangsu coast during AD 1128 to 1855. The paleo-Xiyang tidal channel that was determined by the paleo-tidal current field and significantly different from the modern one, was in existence during the Holocene transgressive maxima and lasted until AD 1128. Following the capture of the Huaihe River in AD 1128 by the Yellow River, the paleo-Xiyang tidal channel was infilled with a large amount of river-derived sediments from AD 1128 to 1855, causing the emergence of some of the previously submerged tidal sand ridges. From AD 1855 to the present, the infilled paleo-Xiyang tidal channel has undergone scouring, resulting in its modern form. The modern Xiyang tidal channel continues to widen and deepen, due both to strong tidal current scouring and anthropogenic activities.

Impervious surface (IS) is often recognized as the indicator of urban environmental changes. Numerous research efforts have been devoted to studying its spatio-temporal dynamics and ecological effects, especially for the IS in Beijing metropolitan region. However, most previous studies primarily considered the Beijing metropolitan region as a whole without considering the differences and heterogeneity among the function zones. In this study, the subpixel impervious surface results in Beijing within a time series (1991, 2001, 2005, 2011 and 2015) were extracted by means of the classification and regression tree (CART) model combined with change detection models. Then based on the method of standard deviation ellipse, Lorenz curve, contribution index (CI) and landscape metrics, the spatio-temporal dynamics and variations of IS (1991, 2001, 2011 and 2015) in different function zones and districts were analyzed. It is found that the total area of impervious surface in Beijing increased dramatically during the study period, increasing about 144.18%. The deflection angle of major axis of standard deviation ellipse decreased from 47.15° to 38.82°, indicating the major development axis in Beijing gradually moved from northeast-southwest to north-south. Moreover, the heterogeneity of impervious surface’s distribution among 16 districts weakened gradually, but the CI values and landscape metrics in four function zones differed greatly. The urban function extended zone (UFEZ), the main source of the growth of IS in Beijing, had the highest CI values. Its lowest CI value was 1.79 that is still much higher than the highest CI value in other function zones. The core function zone (CFZ), the traditional aggregation zone of impervious surface, had the highest contagion index (CONTAG) values, but it contributed less than UFEZ due to its small area. The CI value of the new urban developed zone (NUDZ) increased rapidly, and it increased from negative to positive and multiplied, becoming an important contributor to the rise of urban impervious surface. However, the ecological conservation zone (ECZ) had a constant negative contribution all the time, and its CI value decreased gradually. Moreover, the landscape metrics and centroids of impervious surface in different density classes differed greatly. The high-density impervious surface had a more compact configuration and a greater impact on the eco-environment.

Quantitative characterization of environmental characteristics of cropland (ECC) plays an important role in maintaining sustainable development of agricultural systems and ensuring regional food security. In this study, the changes in ECC over the Songnen Plain, a major grain crops production region in Northeast China, were investigated for the period 1990-2015. The results revealed significant changes in climate conditions, soil physical properties and cropland use patterns with socioeconomic activities. Trends in climate parameters showed increasing temperature (+0.49°C/decade, p < 0.05) and decreasing wind speed (-0.3 m/s/decade, p < 0.01) for the growing season, while sunshine hours and precipitation exhibited non-significant trends. Four topsoil parameters including soil organic carbon (SOC), clay, bulk density and pH, indicated deteriorating soil conditions across most of the croplands, although some do exhibited slight improvement. The changing amplitude for each of the four above parameters ranged within -0.052 to 0.029 kg C/kg, -0.38 to 0.30, -0.60 to 0.39 g/cm³, -3.29 to 2.34, respectively. Crop production significantly increased (44.0 million tons) with increasing sown area of croplands (~2.5 million ha) and fertilizer application (~2.5 million tons). The study reveals the dynamics of ECC in the Songnen Plain with intensive cultivation from 1990 to 2015. Population growth, economic development, and policy reform are shown to strongly influence the spatiotemporal changes in cropland characteristics. The study potentially provides valuable scientific information to support sustainable agroecosystem management in the context of global climate change and national socioeconomic development.

Tidal flats, a precious resource that provides ecological services and land space for coastal zones, are facing threats from human activities and climate change. In this study, a robust decision tree for tidal flat extraction was developed to analyse spatiotemporal variations in the Bohai Rim region during 1984-2019 based on 9539 Landsat TM/OLI surface reflection images and the Google Earth Engine (GEE) cloud platform. The area of tidal flats significantly fluctuated downwards from 3551.22 to 1712.36 km² in the Bohai Rim region during 1984-2019, and 51.31% of tidal flats were distributed near the Yellow River Delta and Liaohe River Delta during 2017-2019. There occurred a drastic spatial transition of tidal flats with coastline migration towards the ocean. Low-stability tidal flats were mainly distributed in reclamation regions, deltas, and bays near the estuary during 1984-2019. The main factors of tidal flat evolution in the Bohai Rim region included the direct impact of land cover changes in reclamation regions, the continuous impact of a weakening sediment supply, and the potential impact of a deteriorating sediment storage capability. The extraction process and maps herein could provide a reference for the sustainable development and conservation of coastal resources.

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.

Climate change is a global environmental crisis, but there have been few studies of the effects of climate change on cereal yields on the Tibetan Plateau. We used data from meteorological stations and statistical yearbooks to assess the impacts of climate change on cereal yields in Tibet. Three types of statistical models were selected: fixed-effects model, first-difference models, and linear detrending models. We analyzed the impacts of climate change (including the minimum temperature, precipitation, growing degree days and solar radiation) on cereal yields in Tibet from 1993 to 2017 at the county, prefecture-level city, and autonomous region scales. The results showed that the sensitivity of cereal yields in Tibet to temperature (minimum temperature and growing degree days) was greater than their sensitivity to precipitation and solar radiation. The joint impacts of climate variables were positive, but the sensitivity and significance varied in different regions. The impacts of minimum temperature, precipitation, and solar radiation were positive in all cities, apart from the negative impacts of growing degree days on cereal yields in Lhasa. The impacts of climate trends on cereal yields in Tibet were positive and the results were in the range of 1.5%-4.8%. Among the three types of model, the fixed-effects model was the most robust and the linear detrending model performed better than the first-difference model. The robustness of the first-difference model decreased after adding the interaction terms between different climate variables. Our findings will help in implementing more spatially targeted agricultural adaptations to cope with the impacts of climate change on the agro-ecosystem of the Tibetan Plateau.