It is essential to clarify the resource list of unstable cultivated land for maintaining ecological balance, ensuring regional food security and promoting the sustainable development of economy and society in the arid areas of Northwest China. At present, the definition and classification of unstable cultivated land in China is relatively general, and the resource endowment of different regions is quite different, so it is difficult to highlight the characteristics of unstable cultivated land in the arid areas of Northwest China with a national standard classification system. In this paper, the connotation and concept of the unstable cultivated land in the arid areas of Northwest China were expounded, and the classification system was constructed according to the unstable factors. Taking Changji Prefecture as a typical case, this paper analyzed the quantity, quality and spatial distribution of unstable cultivated land. The main results are as follows. (1) The definition of unstable cultivated land in the arid areas of Northwest China is as follows: limited by ecological factors (desertification, soil salinization, etc.), or production factors (water, soil, etc.), or socio-economic factors (location, farmland infrastructure, etc.), it is difficult to stabilize production, and continuous cultivation will threaten ecological security of cultivated land ecosystem and surrounding environment, and there is uncertainty in the follow-up land use types. Unstable cultivated land can be divided into four types: productive unstable type, ecological unstable type, socio-economic unstable type and mixed unstable type. (2) The area of unstable cultivated land was 14.56 ten thousand hm² in Changji Prefecture, accounting for 22.37% of the total cultivated land area. Ecological unstable type, productive unstable type, mixed unstable type, and socio-economic unstable type accounted for 36.54%, 34.03%, 17.94% and 11.49% of the total area of unstable cultivated land, respectively. (3) The unstable cultivated land was mainly at low-grade level in Changji Prefecture, and the fourth to sixth grade cultivated land accounted for 79.96% of the total area of unstable cultivated land. Our results are of great significance for the deep understanding of the unstable cultivated land in the arid areas of Northwest China, and provide scientific support for the effective management of cultivated land resources in the case area.

The large-scale expansion of cultivated lands in arid region has caused water overload and a series of ecological problems. Therefore, conducting the scientific assessment of the scale of suitable cultivated land in arid areas can provide reference for sustainable development of agricultural and ecological environment. In this research, five years, 2000, 2005, 2010, 2015, and 2018 were selected as study periods. Water resources were considered as the limiting factor, and a living-production-ecology water consumption structure was built in this research, which is suitable for local socioeconomic development and eco-environment characteristics. The water and heat balance method was improved coupling physical factors like planting structure and crop coefficient in different growth periods, and management factors like irrigation guarantee rate and mulching. Changji Hui Autonomous Prefecture was selected as a case study. The results show that the available water amount of the scenario of critical arable land area for planting decreased from 3.175 billion m³ in 2000 to 2.483 billion m³ in 2018, while the available water amount of the scenario of optimal arable land area for planting decreased from 2.763 billion m³ in 2000 to 2.110 billion m³ in 2018. The total planting area proportion of cotton and wheat increased from 43.58% in 2000 to 59.08% in 2018. Among the main crops, cotton and wheat had lower water requirements after being compensated by precipitation, while the sown area proportion of both increased, indicating that the planting structure is evolving toward the aspect helpful to expansion suitable cultivated land. In the five years, the optimal arable land area which can ensure adequate ecological water consumption is between 28.93 ten thousand hectare and 48.97 ten thousand hectare, while the critical arable land area which can ensure minimal ecological water consumption is between 42.63 ten thousand hectare and 67.83 ten thousand hectare. Available water for plant industry declined with fluctuations. Although the factors affecting the scale of suitable cultivated land fluctuated, under the scenarios of critical and optimal scales of arable land, the overload degree of cultivated land scale showed an upward trend, which varied from -55.15% and -39.41%, at no overload level, in 2000, to 19.92%, a level close to severe overload, and 71.37%, a level of far exceeding severe overload, respectively. The scale of local cultivated land has presented an overload development level.

The large-scale expansion of cultivated land in the arid region has caused water overload and frequent ecological problems, so it is urgent to reduce the area of cultivated land to save irrigation water. Therefore, exploring the spatial optimized scheme of ecological cropland conversion under the constraints of water resources can not only contribute to resolving the current ecological problem of arid areas, but also help implement land use planning and decision-making. Until now, the research on quantitative analyses of the multi-benefit contradiction of the cropland-conversion plan is still insufficient. Therefore, a spatial optimization allocation and trade-off analysis model for ecological cropland conversion is built in this study. Taking Qitai County as a case study, we built a solution group of ecological cropland conversion under the constraint of water resources. Two scenarios, priority for maintaining cultivated land scale and priority for ecological environment, were designed in this research to realize the spatial simulation and optimization of ecological cropland conversion by Ant Colony Optimization Algorithm. Results show that the cultivated land area of Qitai County is 99.39 thousand hectares in priority for maintaining cultivated land scale scenario, and 69.55 thousand hectares in priority for ecological environment scenario. In the cropland-conversion process, the proportion of ecological water consumption in the river channel accounted for 10% of the total water consumption in the cultivated land retain priority scenario and 30% in the ecological protection scenario; and the amount of windbreak and sand fixation increased from 7.13 million tons to 8.17 million tons, while the economic benefit decreased from 3.49 billion yuan to 2.48 billion yuan. Through comparing the reduction of unit economic benefit producing the increasing proportion of unit ecological benefit, the scenario that cultivated land area decreased to 83.49 thousand hectares was chosen as the optimal one considering the trade-off between economic and ecological benefit. The cropland-conversion areas were mainly located in the northeast, northwest and southwest edges of the farmland concentration area in Qitai County, which will benefit the prevention and control of desertification in the north and the protection of water resources in the south. This research realizes the spatial simulation and optimization of the ecological-conversion plan under the constraints of water resources in arid areas, which provide significant reference to agricultural management and ecological protection.

Soil organic matter (SOM) plays an important role in improving soil fertility and crop productivity, and studying its spatial variability can provide a scientific basis for targeted fertilization and sustainable land use and management. This paper selected Changji Prefecture of Xinjiang as the study area, and used three-stage SOM data (the second soil survey, 2010 and 2018) to calculate the generalized dimension spectrum D(q), multifractal singularity index ɑ(q) and the multifractal spectrum function f(ɑ(q)) based on the multifractal method to explore the dynamic changes of SOM spatial variability. The results showed that: (1) The average SOM contents in the three periods were 10.46, 16.69 and 18.16 g/kg, respectively, showing an upward trend. However, the SOM contents of all counties were lower than the national average level (24.30 g/kg) in 2018. (2) The spatial distribution of SOM in Changji Prefecture had non-uniform multifractal characteristics from the second soil survey to 2018. The distribution range of SOM value gradually became narrowed, and the spatial distribution variability decreased, tending to be uniform. The degree of SOM spatial variability in Fukang city, Jimusaer county, and Mulei Kazakh autonomous county increased slightly from 2010 to 2018. (3) In 2018, the spatial distribution range of SOM widened from west to east, with an increasing variation degree, and internal differences became larger, tending to be non-uniform. (4) In the three periods, all the low-value data had a greater variability, with the variation degree being higher than that of the high-value data. Fukang and Mulei were dominated by the high-value data in 2018. Long-term farming had increased the SOM content, and the spatial distribution gradually tended to be uniform. However, there was obvious spatial heterogeneity of SOM. It is necessary to adopt targeted approaches to improve overall soil fertility in different parts of the study area. It is recommended to promote targeted fertilization and to improve irrigation and farming measures in the places with high spatial variability of organic matter, such as Fukang, Jimusaer and Mulei.

It is meaningful for guiding regional agricultural fertilization management measures and improving farmland soil fertility to quantitatively describe the impact of cultivated land reclamation tracks on soil fertility changes at a regional scale. This study identified the cultivated land reclamation tracks by superimposing multiple periods of land use data based on a large number of sample data in 1980 and 2018, to analyze the effects of initial land use and soil types and cultivation years on soil fertility changes in Changji Prefecture, Xinjiang. The result were as follows: (1) Among the current cultivated land in 2018, 90.12% of the original land type was grassland, and 9.88% of the original land type was unused land. The content of other soil fertility indexes increased except for the decrease of available nitrogen (AN) content. Except for soil organic matter (SOM), the spatial variability of other indicators increased. (2) The SOM content reduced because of the reclamation of high-coverage grassland. The reclamation of grassland and unused land would reduce AN content. (3) With the increase of cultivation years, SOM showed a slow increase and gradually stabilizes; while the available nutrient content increased in a short period of time, and stabilized or began to decrease after reaching a certain number of years because of the threshold effect. (4) The loss of SOM caused by grassland reclamation gradually recovered after the cultivation period reached the medium-long term. The SOM content of current cultivated land that the original land type was unused land was always positive. The loss of AN caused by reclamation of grassland and unused land had not been recovered after 38 years of cultivation. (5) The plots with the initial soil types of meadow soil and shrub desert soil had higher nutrient content, and brown calcium soil and gray desert soil had lower nutrient content. The SOM content of current cultivated land that the original soil type was meadow soil decreased. Therefore, it is recommended that the application ratio of fertilizer should be reasonably adjusted, and the potassium fertilizer should be increased. In addition, nitrogen fertilizer should be applied in low intensity and high frequency.

The development of nuclear power industry is closely related to international climate change negotiation, global production chain, geopolitics and national security, as well as national industrial competitiveness. Therefore, it is of great theoretical and practical significance to study the spatial evolution and national competitiveness of nuclear power industry. After outlining the evolving stages of nuclear power industry in the world, this paper analyzed the geographical characteristics of nuclear power industry from both national perspective in the whole world and locational perspective of 198 nuclear power plants in different countries. Furthermore, the competitive advantages of the nuclear power industry of 34 nuclear power countries in operation were evaluated by combining the comprehensive evaluation indicators with the complex network analysis of trade flows between countries. The competitive differences among countries were also compared from the detailed aspects of the support capacity of ore minerals, nuclear equipment and parts, and the scale capacity of nuclear power plants in operation. The main results are as follows. Firstly, there are great differences among countries towards the development strategy of nuclear power industry. Although the global nuclear power capacities in operation are mainly concentrated in the developed countries currently, Asia will become the center of global nuclear power industry in near future with the expansion of nuclear power capacities in Asian countries. Secondly, the nuclear power plants are mainly located in regions close to the densely populated areas that have a large demand of electricity, even though the physical geography and economic level vary greatly among countries. Thirdly, the global trade networks of nuclear reactors and parts show an obvious hierarchical system and a core-periphery structure, indicating that the competitiveness and centrality of main nuclear power countries are more powerful. On the whole, the United States, Russia, Canada, France and China rank among the top five countries in terms of comprehensive competitiveness in nuclear power industry. Finally, suggestions for the developmental strategy of China's nuclear power industry are provided. With the emergence of new nuclear power countries and expanding demand markets of nuclear energy, the balance and the flow pattern of the existing international nuclear power industry will be reconstructed, which urges China to make a comprehensive plan and strategic pathway for its nuclear power industry development with special attention being paid to the whole production chain.

Exploring the export network expansion of China′s ICT products helps to better understand the global-local interactions, which would shed light on the relationship between international trade and internal geography of industries. We propose that export network expansion of ICT products would condition on local cluster networks and information spillover effects among exporters. Local cluster networks represent effects of cluster specialization and cognitive proximity while information spillovers include export experience spillovers and spillovers from foreign investment. Using Customs Data of China, this study describes the dynamic pattern of export network expansion of China′s ICT products and conducts an empirical analysis to identify the driving forces of export network expansion of China′s ICT products. Since the beginning of the 21^st century, China′s ICT export has experienced four stages of development: vigorous and rapid growth (2000-2006), financial crisis response (2007-2009), recovery and adjustment (2010-2013) and the ebb of foreign investment (2014-2016). China′s ICT export is characterized by high proportion of foreign enterprises and large share of processing trade. It is found that although still concentrated in the coastal region, ICT exporters have been increased from the inland provinces such as Sichuan and Chongqing and export markets have been expanded from the traditional markets such as USA, Japan, and western European countries to the emerging markets including Southeast Asia, Latin America and the BRICS. It is further found that significant export expansion has been reported in the following trade flows: from the coastal provinces to East Asia and North America, from the western provinces to North America and Western Europe and from the central provinces to North America and East Asia. Although the market expansion priority differs between two periods of 2000-2008 and 2009-2016, there are some similarities in the major trade flows and the market destinations of ICT export among different provinces. Panel data regressions further show that both local cluster networks and information spillover effects have significant positive effect on the growth and specialization of China′s ICT export and the results are robust with the consideration of labor costs and external transportation linkages.

The maritime service industry has become a key driving force for promoting the spatial structure adjustment and economic development of port cities and is also a core element for enhancing the global competitiveness of hub port cities. Based on the chain network model, the regression model and the list of British Lloyd's Maritime Enterprises, this paper studies the spatial shaping process of the node cities and inter-city links in the global advanced maritime service industry in 1982-2018. The study analyzes the relevance between the connectivity or the number of advanced maritime service producers in the node cities and the shipping, economic, political and cultural location factors. The analysis concludes as follows: (1) Advanced maritime service producers mainly gather in Europe, the Mediterranean and Asia-Pacific region. The east-west market formed by these three regions is the main line of the global advanced maritime service industry. The main spatial pattern changes from "T" shape to triangle. The barycenter of the network is constantly moving eastward and has moved from Europe to the Asia-Pacific region. (2) The network status of the node city is closely related to the strength of the connection between this node city and the top cities and has nothing to do with the extensiveness of the city connection. Node cities can quickly improve their strategic position by establishing strong links with international shipping service centers. (3) The location of the advanced maritime service industry is mainly influenced by capital, technology and market. Its layout is close to customers and markets. These three factors also affect the strength of the aggregation effect of high-end shipping service industry activities. The advanced maritime service industry tends to be knowledge-intensive. (4) With the influence of economic globalization and technological progress, the significance of the relevance between container throughput or regional economy and the layout of the advanced maritime service industry has increased. The significance of the population, ports and administrative centers disappear. The research results reveal the enlightenment and experience of the space-time evolution of the global advanced maritime service industry and provide useful references for the efficient development of international shipping service centers.

Many studies have proved that there is a good interaction between transnational migration and foreign direct investment. As FDI in Africa has been growing rapidly since the beginning of the 21st century, the problems still need to be solved: what is the role of transnational migration in this process, and what is the spatial influence pattern of transnational immigrants from different flows and countries on FDI. The spatial pattern of transnational migration and its influence on FDI were analyzed by adopting the software of ArcGIS and DPS based on the World Bank Database and African Statistical Yearbook in Africa since the beginning of the 21st century. The results show that the transnational migrants by country of origin or destination are concentrated in North Africa and Sub-Saharan Africa respectively, the former gradually forms an agglomeration pattern of immigrants centered on "Morocco-Egypt-Sudan" while the latter is most concentrated in C?te d′Ivoire but gradually replaced by South Africa. FDI is most heavily concentrated in North Africa, but relatively less in South Africa, East Africa, West Africa and Central Africa; and the difference between South Africa, East Africa, West Africa and Central Africa decreases as time goes on. The spatial overlapping of gravity center between transnational migrants by country of destination and FDI is always in a low and stable fluctuation trend, but the center of transnational migration by the country of origin is far away from the center of FDI, with a large fluctuation range, and at the same time, the center of FDI migration is more complex and the migration distance and rate are the most important, showing an overall migration trend from southeast to northwest. The spatial coupling process of gravity center between African transnational migration and FDI shows a wave-style trend that the coupling curve of their gravity centers firstly moves in one direction and then in reverse, while compared with transnational migrants by country of origin, the value of the spatial overlapping and consistency index between transnational migrants by country of destination and FDI is higher, showing that the transnational migration by country of destination has slightly higher attraction to FDI, which is consistent with the results of Grey Correlation Analysis.

Human capital is the key driver of urban innovation and development. In 2017, the "vying for talent" competition was initiated by some second-tier cities, since then cities have been competing each other fiercely for recruiting and retaining talent. This paper focuses on China′s "first-class" university graduates, who are regarded as the main target of the "vying for talent" competition and an important carrier of human capital. Based on 2018 Graduate Employment Reports, this paper demonstrates the spatial mobility of graduates using Cartogram. In addition, an evaluation system for assessing talent policy is constructed through analyses of the talent policies issued by different cities. With a directional migration model, the determinants of graduate mobility are explored. The results reveal that there are significant regional disparities in retention rates, with the geographical patterns of the Y-shaped low-value areas in the northeastern, northwestern, and central regions, and the U-shaped high-value areas covering east coast to southwest. Graduates have been accumulating spatially, and the T-shaped cluster along east coast and the Yangtze River Economic Belt has formed. The spatial patterns of "neighborhood interaction" and "long-distance unidirectional flow" are presented between the city of university and the city of employment. Moreover, the differences in city attractiveness are remarkable. First-tier cities are preferred by graduates, even though limited talent policies have been implemented there. Some second-tier cities have issued talent policies to make up for the lack of attractiveness in economy and amenities. The findings suggest that economic factors, such as income level and technological innovation, as well as amenities including natural and cultural environment, educational resources, and public transportation are positively associated with the volume of graduates inflow. It has been found that a higher ratio of house price to income has squeezed out university graduates. With regard to talent policies, only relaxed hukou policy has a strong effect on attracting graduates, whereas the effects of housing and employment policies are relatively limited. However, it needs to be noted that talent policies may take a longer time to show effects, which requires follow-up investigation. In addition, heterogeneity at the individual level in terms of place of origin, major, etc. should be explored in the future studies.

Currently, urban expansion and quality growth constitute the main contradiction in China′s urbanization development. How to measure the coordinated evolution of the two factors has become an important issue for the sustainable development of regional cities. This paper takes the third growth pole of China's economy, the Bohai Rim region as the research area. Based on the understanding of the urban system theory, a multi-dimensional integrated urban scale and quality measurement system is constructed, and the spatio-temporal evolution and coupling relationship between urban scale expansion and quality growth are analyzed by using the Theil index and decoupling model. The influence mechanism of urban system high-quality operation is explored in both internal and external aspects. The results show that: (1) From 2000 to 2019, the urban scale expansion and urban quality growth in the Bohai Rim region continued to rise, and showed certain spatial pattern characteristics, in which Beijing-Tianjin-Hebei (BTH) showed a "concentric circle" pattern of high-medium differentiation, Shandong Peninsula showed an "axis and wing" pattern of medium-high value agglomeration, Liaodong Peninsula showed a "mutation" pattern of low-medium-high areas coexistence. (2) The regional differences of urban expansion and quality growth in the Bohai Rim are generally reduced, with the regional differences in the three regions occupying the leading position. Reduction speeds of urban expansion are in an order of Shandong Peninsula > BTH > Liaodong Peninsula, and reduction speeds of urban quality growth are in an order of BTH > Liaodong Peninsula > Shandong Peninsula. The evolution trend of cities in different regions is complex and diverse. (3) The decoupling type of urban expansion and quality growth in the Bohai Rim region has experienced an evolutionary process from "SND-WD" to "WD-SD". The decoupling state tends to be coupled as a whole, and the degree of decoupling is in an order of BTH > Shandong Peninsula > Liaodong Peninsula. (4) The urban expansion, quality growth and their coupling and optimization in the Bohai Rim region are the manifestation of the comprehensive effects of the internal and external factors influencing the urban system. Many different factors promote different urban systems to transform from scale expansion to quality growth through long-term regulation, conditional effects, slow regulation and effective intervention.

Since the reform of the housing system at the end of the 20th century, the number of commodity houses has increased sharply over the last two decades. As time goes by, the early constructed houses are now facing a set of serious issues, such as aging, environmental degradation, outdated design, and low efficiency of land use. Therefore, these old houses need to be renovated. However, it is a great challenge to deal with the intricate benefits among three major stakeholders, including the government, developer and houseowner. In order to promote the renovation of old residential areas, it is essential to uncover the complicated relationship among these three stakeholders in terms of their benefits. Through interpreting the connotation of land-use right, land development right and housing value, this paper analyzes the roles of the government, developer and houseowner that they should play during the process of the renovation of old residential areas. Furthermore, the tripartite relationship among three the stakeholders under the market-leading mode of renovation of old residential areas were revealed on the basis of the practices in Shenzhen. With a comparison with the other two modes of renovation of old residential areas in Shenzhen (i.e., Ludan-village mode and shantytown renovation mode), we found that the market-leading mode was less competitive because there exist phenomena of "role-omission", "role-offside" and "role-absence" among stakeholders. As a consequence, the benefits have been usually distributed disorderly and unevenly under the market-leading mode. In general, the houseowner lost their benefits, which have been obtained by the developer and the government. Thus, the unfair distribution of the benefits among three stakeholders hinders the process of renovation. Furthermore, on the basis of Ludan-village mode, which is regarded as a successful solution to the renovation of old residential areas in Shenzhen, a vision for the renovation as "going back to its role" has been proposed. Also, the principle of "regional coordination" is addressed under this vision. The discussion on the relationship of tripartite stakeholders in the renovation of old residential areas will contribute to enriching the research on this field and providing a useful reference for the similar issues in other cities.

The suburbs of megacities present a high dependence on the functional radiation of the central city, and there exist high relevance and competitiveness under the coordinated development of regions. A comparative study on the benefits of construction land in the suburbs of megacities is helpful to distinguish the development quality between different regions, so as to provide support for the rational allocation and prediction of regional resources in mega-urban areas. Based on the "core-periphery" theory, and on the basis of the existing construction land benefit evaluation method, this paper constructs a "horizontal-level" model between the same level areas (city suburbs and counties) and a "longitudinal-level" model (city suburbs and counties and central urban areas). On the basis of comparison of the benefits between the suburbs and counties of the city, the dimension of comparison of the benefits between the suburbs and counties and the central urban area has been introduced, and the "population-economy-space" multi-system comprehensive benefit evaluation method to make the quantitative evaluation of the model has been improved. The comparative research model for the benefit of construction land in the suburbs of megacities has optimized in the following two aspects: (1) the construction land benefit of the population-economy-space system replaces the previous method of comparison of the benefits of a single system of population and economy, which focuses more on the comparison of social benefits. (2) To add the vertical dimension compared with the central urban area and based on the judgment of the relative advantages of the suburbs and counties of the city, the changing trend in the regional hierarchy of megacities can be further clarified. This paper takes 11 districts and counties in suburban Tianjin as an empirical study, and obtains the following conclusions: (1) In terms of regional benefit levels, the benefit structure of Tianjin's suburbs has gradually changed from a single node to an axial expansion of the Beijing-Tianjin-Binhai New Area. The expected multi-core and multi-polar network space structure has not been fully established. (2) The benefit polarization in the central city is obvious. And the "flat" structure of benefits in the suburban and outer suburbs is significant. There is a great gap in benefit levels between suburban counties and central urban areas and lack of intermediate gradient levels. This feature is mainly manifested in the relative convergence of the benefits of the suburban and outer suburbs. Therefore, controlling the supply of land resources in the suburbs and optimizing the industrial development model of different benefit regions can effectively enhance the benefits of construction land in the suburbs and optimize the regional spatial development structure.

Industrial structure transformation is the key to accelerate economic development. In 2000, the Chinese government officially set Fuxin as the first transforming pilot in Northeast China. Since then both resourced-based and non-resource-based cities in Heilongjiang, Jilin and Liaoning provinces that used to be dependent on heavy industries have adjusted and upgraded economic structures. This article tried to compare the industrial structure transformation levels between resourced-based and non-resource-based cities in Northeast China, where most cities had relied on mineral resources for over half a century. According to the industrial development theories, two indicators, rational rate and upgrading rate, are frequently used to evaluate the structural transformation in a particular city. This paper took these theories as reference, compared both rational rate and upgrading rate between two cities, and used panel regression to find the factors influencing industrial development. All the data came from National Bureau of Statistics of China and provincial statistical yearbooks (2001-2018). Some conclusions can be drawn as follows: (1) Both resource-based and non-resource-based cities revealed strong fluctuations in development. The periodic characteristics were highly related to up-down policies. The industrial structure transformation of all the cities have been achieved and upgraded quantitatively and qualitatively. In 2017, the there were small differences between resource-based cities and other types of cities. (2) During the transformation, the average levels of both rationalization and upgradation of the resource-based cities were lower than those of others, and the high-level cities were barely changed, which showed different spatial distribution features. (3) Environmental regulation and ownership structure can be beneficial to the industrial development for all the cities. Other factors such as technology level, resource dependence, investment level, and economic openness played different roles in different types of cities. (4) The commonalities and differences between resource-based and non-resource-based cities revealed the difficulties for industrial transformation in Northeast China. In the future, the acceleration of serving industries, ownership structure, and environment regulation could promote the further transformation development.

The Yangtze River Basin and Yellow River Basin are important ecological barriers in China, which is of great significance to regional sustainable development. In recent decades, the human activities have changed the natural landscape of the two great river basins, which causes the destruction of ecosystem functions. Understanding the changes, interactions, and drivers of ecosystem services are critical for the improvement of ecosystem management in the above basins. Using the data of land use, NDVI, soil type and meteorology, this paper analyzed the spatial and temporal changes of vegetation net primary productivity (NPP), water yield (WY) and soil retention (SR) in the Yangtze and Yellow river basins from 2000 to 2016. The correlation analysis method was used to explore the trade-off and synergy between ecosystem services, and the constraint lines were extracted to compare the constraint effects between WY and SR in the above two basins. The results showed that: (1) From 2000 to 2016, the NPP in the two river basins increased at a rate of 3.21 gC/m² and 3.92 gC/m², respectively. In the Yangtze River Basin, WY increased at a rate of 1.25 mm/a and SR decreased at a rate of 55 t/hm², while in the Yellow River Basin, WY decreased at a rate of 0.04 mm/a and SR increased at a rate of 3.31 t/hm². (2) There was a synergistic relationship between NPP, WY and SR in the two basins. And the constraint line between NPP-WY and NPP-SR was hump-shaped constraint in the Yangtze River Basin. (3) In the Yellow River Basin, there was a convex-waved type constraint line between NPP and SR, and hump-shaped constraint line between NPP and WY, while there was an exponential relationship between WY and SR. Precipitation is the main factor influencing the constraint lines between ecosystem services. Still, quantitative research on ecosystem services in different watersheds and the influencing factors is of great significance for understanding and optimizing ecosystem services in different regions.

The rapid social and economic development led to the gradual emergence of the multi-functionality of cultivated land. However, existing studies mainly evaluate the function of cultivated land from the perspective of a single function, while the comprehensive investigation of the production-living-ecological function of cultivated land based on elements still remained in the exploratory stage. Therefore, the connotations of cultivated land, cultivated land function, and cultivated land production-living-ecological function were defined based on the systematic analysis of the cultivated land system as well as its elements, and the evaluation framework and the zoning conceptual model of the production-living-ecological function of cultivated land were theoretically constructed. The empirical results showed that the production and living functions of more than 80% of cultivated land and the ecological function of more than 60% of cultivated land were medium or above, which indicated that the degree of development and utilization of cultivated land in Nan′an City was at a high level, and there might be overlap, occupation, and agglomeration between different functions. Under the influence of natural production potential and geographical location conditions, arable land reach level and cultivated land dependence, ecological base condition and ecological protection policy, the production-living-ecological function of cultivated land showed evident regional convergence. About 50% of the cultivated land in Nan′an City had a single function, indicating that the comprehensive level of cultivated land function was still low. The area proportions of function combination models indicated that although cultivated land still provided important food security and social security, the development of cultivated land had been endangering regional ecological security. Therefore, it is necessary to take differentiated utilization, protection, and management strategies according to the spatial distribution, combination pattern, and function intensity of cultivated land functional zoning. Our study could provide theoretical and methodological support for the multifunctional utilization and management of cultivated land under the background of rural revitalization strategy and national spatial planning system construction.

Urban heat island effect (UHI) is affected by multiple factors on the urban surface, while the situation of a mountainous city is more complicated. To detect the cause of UHI, this article takes a typical mountainous city of Chongqing as an example. Firstly, we collected multi-source spatial data based on Landsat8 OLI/TIRS images, high-precision vector building, etc. as basic dataset. Then, the model method of urban land surface temperature retrieval (LST), normalized vegetation index (NDVI) and the sky view of factor (SVF) etc. are applied to obtain spatial pattern of each factor. Finally, with focus on the urban built-up area, the binding force of each factor on the UHI is analyzed by the method of geographic detector. Through the above steps, this study found that: (1) Around the whole metropolitan area, the spatial heterogeneity of urban thermal field is significant. From the spatial pattern of each factor, we can see that some factors, like vegetation coverage (NDVI), urban surface elevation (CSE) and the sky view of factor (SVF), have global binding performance for UHI, while others like building density (BD), building volume rate (BVR) and road network distance (RD) have local binding performance for UHI. (2) Within the urban built-up area, the top three factors influencing the spatial pattern of UHI separately are vegetation coverage (q=0.782), urban surface elevation (q=0.499) and building density (q=0.496). Besides, the local constraint factors, like building density (BD), building volume rate (BVR) and road network distance (RD), performance strong binding on UHI, yet among them show little difference. In addition, for there is no significant spatial difference in urban sky horizon within the high-density built-up area, the overall effect of the sky view factor (SVF) on urban heat island is relatively small (q<0.1). (3) Through interactive detection and analysis, the results suggested that each influencing factor shows overlapping constraints on the spatial distribution of UHI within the built-up area of the city. From the criterion q value of the factor binding force, we can see that interaction of two factors will increase the interpretation of the UHI. In other words, the superposition explanatory degree (q(X_i∩X_j) is stronger than the independent interpretation degree, whose superposition interpretation degree q value is between 0.50 and 0.82.

Under the background of tourism development, the changes in Xi′an′s Huimin historical and cultural district are causing a reconstruction in the cultural memory of local residents amidst the urban planning of historical and cultural streets. Aside from its role as part of the city′s historical and cultural tourism area, Huimin street is a residential neighbourhood comprising many residents who have their everyday experiences and daily cultural memory associated with living in this particular area. Given that the vast majority of the inheritors of cultural memory is the local residents who have lived in this area for generations, the changes made to their social and cultural memory of shared community space as a result of tourism development is therefore of great significance and relevance to them, their families and their overall local identities. Based on the theoretical framework of cultural memory and using in-depth interviews of 23 local residents, this paper explores the resultant changes in intergenerational cultural memory as a result of tourism development. Our research findings show that: (1) Tourism development creates distinctive differences in the collective cultural memories amongst the older and younger generations. Despite the differences in the inherited cultural memory, these collective memory still plays a crucial role in linking the past and the present to influence the residents′ social and cultural identification within the district. (2) The resiliency and strength of cultural memory is dependent on the depth and extent of the personal, cultural and social interactions between places, people and events. Significant local landmarks such as Qingzhensi, the long-standing restaurants in the neighbourhood′s alleys, residents′ personal homes amongst other intergenerational shared spaces are spatially important for generations of parents and children to share memories, which represent an enduring connection between the olden times and the present in the ongoing tourism development of Huimin Street. (3) The commonalities in cultural memory can strengthen residents’ social and personal identity and foster stronger community bonds even while they face drastic changes in their key surroundings as a result of the sweeping effects of tourism development.

Journey-to-crime is a behavioral process of criminals searching for the targets and places that meet the needs of crime. It measures the spatial distance of the criminal from the initial location to the predetermined location. This is an important technical contribution of criminal geography in crime prevention, case detection and other police practices. Restricted by the limited research data, empirical research on journey-to-crime in China is relatively lacking. This paper studies the spatial pattern and influencing factors of journey-to-crime in pickpocketing in Nanguan District of Changchun from 2010 to 2016. The paper points out that: 1) The average distance of journey-to-crime in the study area from 2010 to 2016 is 5.74 kilometers, which shows an obvious spatial attenuation effect. The spatial pattern is plunder nearby, and there is a crime buffer zone, 2 kilometers away from the criminal′s residence; 2) There is an overlap in space of the areas with high incidence of pickpocketing crime and the residence of crime groups. And the spatial pattern of crime in this area is mainly plunder nearby; 3) By constructing a sequencing logit model, the influence of the uncertainty of measuring journey-to-crime distance on analysis results can be weakened. The regression model verifies the significant impact of gender, domicile, employment and criminal record, amount of money involved and type of crime location on journey-to-crime distance. Among them, the positive correlation between the amount of money involved and the travel distance verifies the prediction of the rational choice theory on criminal motivation. Based on the case study of pickpocketing crime in China′s big cities, this paper indicates that the average journey-to-crime distance, spatial pattern and influencing factors of pickpocketing crime in China and western cities are similar or consistent, which further promotes the combination of criminal geography on criminal behavior research between China and Western countries. Through analyzing the influence of the residence of crime groups on their journey pattern, the urban crime phenomenon and the social management problems of floating population in China under the background of high-speed urbanization can be hopefully reflected upon, thereby expanding the current literature on journey-to-crime. This paper is of a practical significance to criminal profiling, crime risk assessing in residential space, guiding crime prevention and assisting case detection.

As one of the most important geological events in the Cenozoic era, the Tibetan Plateau's (TP) uplift has profoundly influenced the Asian and global climate and environmental evolution. Therefore, the TP has become the focus of geography research subject at home and abroad and has obtained great achievements. However, there are still many problems to be further explored. In this study, Hoh Xil, the hinterland of TP, was taken as the research area, and a 106-meter lake sedimentary borehole called BDQ06 was obtained in August 2006, geographically at 35°13′05″N and 93°55′52.2″E. The grain size and total organic carbon of lake sediments are chosen as climatic indicators. The approaches of Power Spectrum Analysis (PSA), Singular Spectrum Analysis (SSA), and the Continuous Wavelet Transform (CWT) are used to analyze the climate evolution cycle. Based on paleomagnetism's chronological framework, paleoclimatic cycle evolution since the last 929 ka has been investigated. The results show that the quasi-periodic components of the earth's eccentricity (100 ka), obliquity (41 ka), and precession (23 ka and 19 ka) exist in the BDQ06 hole. Meanwhile, the periodic components of 84, 66, 54, 36, 31, 27, 17, 15, 12, 11.5, 10 ka, and so on are found in the record. All this indicates that the climate changes in the Hoh Xil area are influenced not only by the earth's orbital parameters but also by other factors in the inner of the earth system. Furthermore, CWT and SSA show that different climate cycles can be superimposed in the same period and exist in different periods. Besides, an obvious climate transition has been observed at 780 ka. The dominant period is 41 ka though the period of 100 ka existed in the record ahead of this time point. However, after 780 ka, the controlling period shifted to 100 ka. Moreover, the climatic periodic characteristic has become gradually complicated since 580 ka BP, which is possibly affected by the change of hydrodynamic conditions caused by the TP's tectonic uplift. We concluded that although the Hoh Xil's climate cycle characteristics are consistent with global features, but they have apparent regional characteristics. Also, the periodic signals of grain size and total organic carbon are not wholly consistent, so the significance of climate proxy indicators needs to be further explored.