The COVID-19 pandemic is considered the biggest crisis confronted with the world after the Second World War, which has brought huge impacts on people’s health and daily life, economic growth and employment as well as national and international governance. Increasing pessimism is buzzing among scholars, critics, entrepreneurs, the mass and even government officials, and views like the end of economic globalization, large-scale spatial restructuring of global supply chains and fundamental change of the world economic governance structure are becoming prevailing on the media. This paper tries to address the issue of the development trend of economic globalization in the post-pandemic era by developing a framework of globalization’s Triangle Structure to understand its dynamics in addition to a summary of the on-going impacts of the COVID-19 pandemic. We argue that the spatial fix of capital accumulation, time-space compression led by technological advance and openness of nations are the three major drivers of economic globalization, and the changes and interactions of these three drivers decide the development trend of economic globalization. From such a dynamic viewpoint, economic globalization is an ever-changing integration process without an end but constant fluctuations. The cost of decoupling of nations from globalization would be very huge because they have been highly integrated by global production networks and trade networks and no nation can afford a complete decoupling. The so-called de-globalization phenomena are just short-term adjusting strategies of nations to cope with power reconfigurations brought by economic globalization. The pandemic will have little impacts, or probably nothing, on the spatial fix of capital accumulation and time-space compression led by technological advance, but may temporarily influence some nations' openness. If the pandemic does not last long, economic globalization will resume from the shock soon after the world goes back to normal, and develop and restructure according to its own dynamics. Thus, we tend to believe the pandemic at most slams the brake of globalization and would not be able to put it into reverse. Economic globalization will not stop or reverse, but develop towards a more inclusive stage.

The study of the spatial diffusion and geographical mode of COVID-19 is of great significance for the rational allocation of health resources, the management and response of public health emergencies, and the improvement of public health system in the future. Based on multiple spatio-temporal scale, this paper studied the spatial spreading process of COVID-19 between cities and its evolution characteristics in China, and then explored its influencing factors. The results are shown in the following: the inter-city spreading process of COVID-19 in China mainly experienced six stages, namely, stage I: diffusion in Wuhan, stage II: rapid multi-point diffusion in space, stage III: rapid increase of confirmed cases, stage IV : gradual decrease of new confirmed cases, stage V: the epidemic under control, and stage VI: cases imported from overseas. In the context of globalization and open regional system, the social and economic development of regions are closely related to each other. With the development of fast and convenient high-speed railway network, the spatial characteristic of population migration shows a cross-regional and hierarchical pattern, and forms a certain spatial cascade structure along the transport corridor. Accordingly, the spatial spread of COVID-19 mainly showsthe characteristics of adjacent diffusion, relocation diffusion, hierarchical diffusion, and corridor diffusion. The study found that geographical proximity, population migration and population size, traffic network, epidemic prevention and control measures have significant influence on the spatial diffusion process of COVID-19. Among different modes of transportation, airplanes play agreater role than others in the early stage of the epidemic. In addition, the population flow during the Spring Festival had a certain impact on the spread of the epidemic. In conclusion, to some extent, the spatial spread process and pattern of COVID-19 epidemic reflects the spatial organization pattern of social and economic activities under the "space of flows" network, which is closely related to the geographical proximity, the social and economic linkages between regions, and the spatial an temporal patterns of human activities. From the perspective of geography, this paper analyzed the inter-city spread pattern of COVID-19 epidemic and provided some implications for prevention and control measures against the epidemic in other countries, and also offered some suggestions for China to deal with public health emergency risks in the future.

As a significant branch of critical geopolitics, popular geopolitics serves as one of the fields which is the closest to daily life. In addition to making up for the aphasia of traditional geopolitics in media field, popular geopolitics has displayed a new exploration path of geopolitics in various fields gradually, including film, radio and television fields, etc. Since its research is still at the initial stage in China, it is not feasible to support the research and development of popular geopolitics by the existing domestic research outcomes. Therefore, by taking 189 literatures highly related to popular geopolitics in Web of Science Database as the research objects, this paper uses the literature research to sort out and summarize the origin, development history, relevant research methods and major topics for discussion of popular geopolitics, and prospects the future research direction of popular geopolitics. According to the research, it can be concluded that: (1) popular geopolitics has inter-disciplinary characteristics such as geography, communication and politics and so on, with research cases area expanding from the US-Soviet region to the whole world. (2) The theoretical support of popular geopolitical research is more abundant compared with the interpretation of post-colonialism through characterization and post-structuralism, and the research on "man" and "thing" is more diversified. (3) The research on popular geopolitics takes example by methods of sociology, communication, anthropology and other disciplines. Its research topics mainly concentrate on the analysis and interpretation of elite’s minds in the media, geopolitical imagination of the public influenced by the media as well as characterization of national mythology in the media and its influence on national identity. (4) Popular geopolitics will create a new development direction by combining other disciplines in the future. There is no doubt that strengthening the research on popular geopolitics has non-negligible theoretical and practical significance. In addition to completing the construction of geopolitical discipline system, its research helps a country to convey a positive image of sun to a group that has no direct contact with it in geopolitical events, eliminate unjust descriptions and discredit, and unite the masses when facing ideological challenges. China’s intensified research on popular geopolitics will help the implementation of the go-global strategy and the realization of national rejuvenation. It can also help the country to make suggestions for establishing a better national image in the development process.

The location choice of emerging industries has always been the focus of economic geography research. "Windows of Locational Opportunity" and "Regional Branching" have different understandings about the relationship between local knowledge base and location choice of emerging industries. This study distinguishes the concepts of innovation cluster and industrial cluster, and holds that innovation cluster is more conducive to focusing on the location selection of emerging industries. Then taking China's fuel cell industry as an example, this study focuses on the applicability of "regional industry bifurcation" theory in the formation of fuel cell innovation cluster. And this paper divides the knowledge base into analytical knowledge, synthetic knowledge and symbolic knowledge. This paper collects patent information, patent citation and cited information, academic papers information of 291 prefecture-level cities in China from 2000 to 2016. With the aid of ArcGIS and Stata software, this paper carries out a spatial pattern analysis and two-step panel system GMM regression analysis, and draws the following conclusions. (1) From the perspective of pattern, the development of fuel cell innovation cluster is mainly concentrated in developed provincial capital cities, and a few other major cities such as Dalian. In the process of innovation cluster development, path dependence is obvious. The correlation coefficient of innovation cluster index of 291 prefecture-level cities in 2000-2005 and 2011-2016 is as high as 0.904, showing significant strong correlation. (2) Local analytical, synthetic and symbolic repositories all have significant effects on the development of innovation clusters, and the lagged first-order term of innovation cluster index is significantly positive, which supports that the local knowledge base has a significant positive impact on the development of emerging industry innovation cluster, and becomes an important evidence to support "Regional Branching". (3) The formation of fuel cell industry innovation cluster is mainly carried out in the way of "Regional Branching". The advantages of developed cities on the knowledge base help them to occupy an advantage in the formation of fuel cell innovation cluster, which leads to the further accumulation of knowledge-based advantages. Therefore, the virtuous circle between knowledge base and innovation cluster is formed, and path dependence is significant. Among the top 20 cities in innovation cluster index, the number of municipalities (at provincial level) and provincial capitals account for 75%, almost all other cities are located in the eastern coastal areas, which shows that it is difficult to open the location opportunity window of ordinary cities.

Most inland cities in China are in the “marginal zone” of export product space all the year round. It is of great significance to break the original path dependence and truly create a "new opening-up plateau" for the transformation and upgrading of regional industrial structure. This paper uses the product trade data of China Customs from 2000 to 2016 and the data of enterprises and governments on-the-spot investigation, through the dynamic dual marginal decomposition and the measurement of industrial transformation and upgrading level, to discuss the evolution and mechanism of the export path of the five cities of Hexi (Jiayuguan, Jinchang, Jiuquan, Wuwei and Zhangye) of underdeveloped inland areas in China. The results show that: (1) the export routes of the five cities can be roughly divided into two categories. Firstly, Jiuquan, Wuwei and Zhangye are in the exploratory stage, which is from the initial path creation to the path differentiation of export, and they are trying to jump from the "marginal zone" to the "core zone" of export product space to create new export paths. Secondly, Jiayuguan and Jinchang have entered a new stage of export path which has been locked-in and need a breakthrough after the initial path creation and enhancing, but they are still in the "marginal zone" of export product space. (2) The two major types of paths in the five cities are mainly dominated by policies and are driven by technological innovation, trade barriers, information networks and transportation networks. However, the eastern developed areas are mainly affected by technological innovation. This reflects the particularity of inland areas. (3) The evolutionary mechanisms of the two types of pathways in Hexi are quite different. Influenced by macro-historical policies, the city's early export path evolution of Jiuquan, Wuwei and Zhangye lags behind. However, under the influence of a series of policies in this century, the evolution of export routes has been differentiated in these three cities. On the contrary, although Jiayuguan and Jinchang accumulated a large number of technical and talent advantages in the early stage and the path evolved rapidly, they fell into the trap of "rigid specialization" later because of the influence of enterprise inertia. The research results are helpful to the underdeveloped inland cities in China to explore effective ways to break through the path of foreign trade.

The transfer of polluting enterprises/industries has reshaped regional development pattern and changed the distribution of environmental pollution, which has a significant impact on regional sustainable development. The research on this transfer is of great significance for pollution control and regional coordinated development. Based on literature review, the article generalizes systematically the concepts and categories of polluting enterprises/industries and summarizes their transfer characteristics, laws, patterns and dynamic mechanisms. The review of the literature showed that: (1) official documents, pollution emission intensity, pollution emission scale are the main basis of polluting enterprises/industries definition and classification. (2) Polluting enterprises/industries form different transfer patterns on different geographical scales, and they transfer in municipal, provincial, and national scales. Three modes (decentralized peripheral areas transfer, centralized functional areas transfer, and moving away from sensitive areas) are formed within the city. The polluting enterprises/industries transfer both from developed cities to less developed cities and from areas with strong environmental regulations to marginal areas with weak environmental regulations among the cities in the province. Neighboring province has the transfer mode that is centered on developed provinces with stronger environmental regulations and spread to neighboring provinces. This transfer pattern has three paths that tend to move to the boundary of multiple provinces, move from the upstream provinces of the river to downstream provinces and move to secondary cities along the traffic line. Inter-provincial transfer of the polluting enterprises/industries forms three modes of cost-oriented, market-expanding and policy-driven factors. ③ The transfer direction of the polluting enterprises/industries presents certain characteristics and laws. We conclude fifteen kinds of transfer directions based on regional, geographic, economic, functional areas, and policy perspectives. (4) The transfer modes of polluting enterprises includes overall transfer and partial transfer. The partial transfer includes migration of production base, process outsourcing, green mergers and acquisitions, establishment of subsidiaries or branches, etc. (5) Economic, social, geographical and policy factors not only affect the transfer of polluting enterprises/industries separately, but also comprehensively form the complex transfer mechanism. In the multi-dimensional complex influence mechanism, the government plays an important role and enterprise heterogeneity, spatial agglomeration effect and system have a significant impact. Finally, the shortcomings of relevant domestic research are discussed, and some thoughts and policy recommendations for polluting enterprise/industry transfer are proposed.

Human health and social development are significantly affected by urban extreme heat. It is a new proposition for human-land relationship in the field of geography to measure the characteristics and social consequences of urban extreme heat. Applying the tool of social vulnerability to studies of urban extreme heat, this paper takes 296 cities in China as research objects and establishes quantitative indicators of urban extreme heat such as high temperature days, high temperature intensity, heat wave frequency, heat wave duration and heat wave intensity. By using daily maximum temperature data, urban statistics and census data, we systematically analyze the characteristics of urban extreme heat. Meanwhile, we construct a framework for urban social vulnerability to extreme heat and based on this framework, we developed a common evaluation index system of social vulnerability according to the three dimensions of exposure, sensitivity and adaptive capacity. Finally, we conduct social vulnerability assessments for the 296 cities, classify social vulnerability levels, and analyze the causes of urban social vulnerability. The results are shown as follows. (1) The extreme heat events are mainly concentrated in southern cities, especially in the eastern and central parts of the country. Although there are fewer extreme heat events in northern cities, the intensity of high temperature is more prominent. (2) The urban exposure index to extreme heat in China has obvious spatial agglomeration characteristics, while the sensitivity index and adaptability index are scattered. (3) Cities with high social vulnerability index are mainly concentrated in most areas of East and Central China, and in a few areas of Southwest and North China. The proportion of cities with high, middle and low social vulnerability index was 25.3%, 46.3% and 28.4%, respectively. (4) The number of social sensitive cities is the largest, followed by high temperature exposure cities, and the number of insufficient adaptability cities is the smallest. In addition, exposure index contributes the most in cities with high social vulnerability index, and sensitivity index contributes the most in cities with middle and low social vulnerability indexes. This study can provide reference and enlightenment for relationship research between disaster and society, quantitative expression of characteristics of urban extreme heat and assessment of social vulnerability to extreme heat.

Existing urban network research mostly focuses on urban linkages or spatial linkages within an urban agglomeration, with most of the research on urban network structure of China based on the relational data of the general and branches of enterprises, while it remains lack of an overall cognition of network linkages between the Chinese urban agglomerations. Based on the data of the 311 financial and professional service enterprises in the list of the Fortune China Top 500 Enterprises, this paper takes the enterprises as cross-scale spatial expressions of urban agglomerations where their headquaters and branches are located, and regards urban agglomerations as interconnected space according to relational geography. Using analytical methods of network analysis, interlocking network model, Pajek and Gephi, this article analyzes spatial relationship between the 19 urban agglomerations and their 41 major cities, with a focus on the finance and professional service sectors, towards an exploration of coordinated spatial development of Chinese urban agglomerations. The conclusions are as follows: on the one hand, Chinese urban agglomerations form a spatial organizational system centered on the 6 urban agglomerations of Beijing-Tianjin-Hebei region, Yangtze River Delta, Pearl River Delta, Chengdu-Chongqing, Shandong Peninsula and Middle Reaches of the Yangtze River, which is consistent with the distributional characteristics of the national central cities, while the other 13 urban agglomerations are non-core spatial organizations served as important support for the expansion of urban agglomerations in China. On the other hand, the spatial coordination of urban agglomerations relies on efficient and optimal allocation of financial and professional service elements. The external contact scope of an urban agglomeration determines its ability to control and configure various service element flows, which in turn affects its coordinated development status. Among them, the Beijing-Tianjin-Hebei urban agglomeration dominates the urban linkages formed by commercial banks, diversified financial investment, insurance, accounting and law firms, the Yangtze River Delta urban agglomeration dominates the securities enterprises’ urban linkages with absolute advantages, and the Yangtze River Delta, the Chengdu-Chongqing and the Pearl River Delta urban agglomerations lead the urban linkages between advertising agencies as well as management consulting companies. This paper attempts to cognize the relational proximity among the urban agglomerations to recognize the cross-scale collaborative mechanism between corporate actions and the urban agglomerations, by which it emphasizes the important role of the horizontal linkages between the urban agglomerations and thus contributes to provide reference for coordinated development of the urban agglomerations in China.

The phenomenon of regional population decline has aroused much attention across the world in recent years, and it is also increasingly obvious in China. Using 1990, 2000 and 2010 population census data, and the national 1% population sample investigation data in 2015, this paper analyzes the evolution trend of regional population decline at the county level in three periods, namely 1990-2000, 2000-2010 and 2010-2015, and identified different evolution types by comparing adjacent periods. We employ a multiple logistic regression model to investigate the underlying driving factors in these processes. The main findings are as follows. (1) The phenomenon of regional population decline became very obvious at the county level, and the percentages of units with population decline in the three periods were all more than 20%. (2) The population decline units expanded significantly from 2000 to 2010, especially in the Northeast region, Sichuan-Guizhou-Chongqing region, and the middle reaches of the Yangtze River, while such units were scattered in the northern part of Jiangsu province and the western part of Fujian province in the Eastern region. (3) The population decline areas presented a trend of slow growth from 2010 to 2015, and only expanded in the Northeast region and Henan province. (4) The factors of economic development level, such as the per capita GDP and the non-agricultural employment ratio, significantly influenced the formation of regional population decline, while the factors of economic development rates, including the growths of per capita GDP and the non-agricultural employment, contributed to the evolution processes of regional population change, and a low economic development rate had been a key factor driving continuous population decline. (5) In addition to economic factors, the natural population growth, including the percentage of the aging population and the birth rate, had an increasing influence on the formation and evolution of regional population decline. According to the above findings, we suggest that the central government should pay more attention to the phenomenon of regional population decline, and take appropriate measures to deal with it, such as promoting the coordinated regional development, adjusting the birth policy to improve the fertility level, and strengthening the planning practice from the perspective of population decline.

Against the backdrop of rapid urbanization in China, enhancing public participation at the community level has become an important national strategy. It is necessary for planners to deploy new approaches to understand public needs and to identify common issues or areas within the community in a timely manner. Participatory sensing, which builds upon the widespread information sharing using the Internet and mobile technology, has provided new opportunities for planners to sense and analyze public sentiment, human mobility patterns and surrounding environments at better spatiotemporal resolutions. This opportunity has gained considerable attention from research community and has spurred a range of studies on topics such as emerging public participation paradigm and urban computing. However, current studies have not systematically investigated the mechanisms and common approaches of implementing participatory sensing in the context of urban community planning. This paper bridges this research gap by proposing a conceptual framework for studying participatory sensing in the community planning context, and by developing a technological framework for processing, integrating and analyzing multi-sourced human sensory data. Particularly, the conceptual framework builds upon the theories of public participation, the principles of participatory sensing, and the inter-relationships among residents, urban communities and urban community planning. A technical framework that synthesizes sensing, computing and application is further proposed. Specifically, sensing refers to collecting various data about how residents use and perceive urban community space; computing refers to extracting useful knowledge regarding human activities and perceptions, individual’s biological information and environments from raw sensed data; application refers to analyzing extracted knowledge for supporting community planning compilation and decision-making. Based on the framework, the workflows of extracting and spatializing residents’ subjective perception, analyzing how different population groups use urban community space, and apply participatory sensing and computing for urban community planning compilation and decision-making are further suggested. The proposed workflows build upon multi-disciplinary methods and aim to shed light on further developments of relevant methods and techniques for utilizing multi-sourced data that support urban community planning. Overall, this study will contribute to the methodological developments of applying participatory sensing for urban community planning. It will also shed light on future developments of new practical approaches for enhancing public participation, and for supporting rational planning evaluation and decision-making in urban communities.

Taking 27 provinces in China as an example, this paper mainly examines the rural poverty reduction and its spatial spillover effects of population urbanization, land urbanization and economic urbanization in China from 2010 to 2017. The results show that: (1) From 2010 to 2017, rural poverty, population urbanization and land urbanization in China's provinces show significant characteristics of spatial agglomeration, while the spatial agglomeration of economic urbanization gradually decreased. (2) Population urbanization has a "U"-shaped character in the rural poverty, while economic urbanization has an inversed "U"-shaped character. Land urbanization has no obvious effect on the rural poverty; however, it mainly shows the potential to aggravate the occurrence of rural poverty. (3) Population urbanization and economic urbanization have obvious spatial spillover effect on rural poverty, meanwhile, they have a "threshold" phenomenon in the spatial spillover effect of rural poverty. The direct effect threshold of population urbanization in poverty reduction in the eastern and central regions has basically been broken through, and the poverty reduction potential is weak, while the spillover effect threshold of population urbanization on poverty reduction in most provinces still exists, and the beneficial spillover effect is still obvious. In contrast, the direct and spillover effects of economic urbanization in all the provinces have broken through the threshold. (4) The urbanization of population should be pushed forward reasonably, and the related system reform should be quickened. We will expand urban space effectively in an orderly manner, optimize the adjustment of urban industrial structure, expand the scale of tertiary industry of the economic development and strengthen its quality upgrading, increase urban employment rate and enhance the overall radiation-driven effect of cities and towns. The allocation and utilization of population, space and resources in the region should be coordinated in an overall way, and the positive "externalities" caused by factor aggregation should be brought into full play to promote long-term, stable and poverty reduction in rural areas, and promote urban-rural coordination and sustainable development.

By analyzing the connotation of the adaptability of rural production space system, and constructing a framework of the adaptability, this research establishes an evaluation index system for the space system in the following three dimensions: the vulnerability, the stability, and the response. Then, taking Jiangjin district of Chongqing as an example and using the adaptive evaluation model, this paper evaluates the operation status of the rural production space system from 2007 to 2017. At the same time, the factors of the adaptability obstacle of rural production space system were diagnosed by using the obstacle degree analysis model, and the indexes of the adaptability of rural production space system and the adaptability obstacle degree of criterion layer were calculated. Based on the above research, by analyzing the factors that cause the obstacle to the adaptability of the rural production space system, this paper puts forward some targeted strategies to solve the current reality of the dilemma in the operation of the rural production space system in Jiangjin district of Chongqing. The results show the following aspects. From 2007 to 2017, there is a trend of rising and increasing volatility of the adaptability of rural production space system in the study area on the whole, which shows that the sustainable operation and development capacity of the rural production space system has been improved steadily. The degree of adaptability obstacle of rural production space system has gradually changed from stability obstacle and responsiveness obstacle to vulnerability obstacle, and the key obstacles of the adaptability of the system include the amount of fertilizer used, the amount of agricultural film used, the total energy consumption of rural production, the area of urban industrial and mining land, and the proportion of rural environmental protection investment. It is the key to enhance and improve the adaptability of rural production space system in the district, which aims, on the premise of developing ecological agriculture and organic agriculture and strengthening environmental protection, to reduce the vulnerability of the system, expand the value-added space of selenium-enriched agriculture, effectively increase rural investment in capital, talent and technology to strengthen the stability and response ability.

Commuting is the main source of CO₂ emissions from urban transport. However, existing studies have rarely paid attention to the differences in the effects of different geographical scales of built environments on residents' CO₂ emissions from commuting and had not yet reached a consensus conclusion. Based on the 2015 travel survey data and multilevel and mixed-effects models, this paper conducts an empirical study on the effects of multi-scale built environments on residents' CO₂ emissions from commuting in Guangzhou, China. The results show that after control for the residential self-selection effect, there are obvious spatial differences in the residents' CO₂ emissions from commuting among neighborhoods. It is shown that the residents in the central urban area generally emit less CO₂ emissions than their counterparts in the suburban area in commuting trips. These are caused by differences in built environments between neighborhoods. In terms of scale, the neighborhood's built environment has the most significant effect on residents' CO₂ emissions from commuting, followed by 1 km-buffer range of neighborhood boundary, and then subdistrict. Moreover, the effect of the built environment of the residence on CO₂ emissions from commuting is more significant than that of the workplace. These findings imply that planning interventions on the built environment should focus more on the neighborhoods in which residents live and the 15-minute walk life circle that is closely linked to the daily travel activities of residents. The distance between residence and workplace should be kept as short as possible, and the residential density of neighborhoods should be maintained at a reasonable level. Furthermore, optimizing the structure of road network and providing more community roads which are beneficial to non-motorized travel could help improve the environment for walking and bicycling and encourage people to use low-carbon, active and healthy travel modes. Although there may be some limitations in the selection of neighborhoods surveyed and random interception approach in the survey that may lead to non-possibility sampling, the conclusions can still provide a scientific basis for constructing a low-carbon urban spatial structure, guiding residents' travel behavior change and formulating targeted policies on low-carbon transportation and land use.

With the popularity of road travel, Chinese backpackers have shifted the place of graffiti activities from cities to non-urban spaces such as highways. Although backpackers’ graffiti is influenced by both traditional travel culture and modern graffiti art, it is different from graffiti in urban areas and scenic spots. Backpackers’ graffiti combines “roaming” and “graffiti” and thus can be regarded as a special spatial practice. The spatio-temporal characteristics of backpackers’ graffiti provide a vivid context for analyzing the importance of road and nodes in tourism geography, for understanding how tourists participate in the place making of destinations, and for exploring how a community can be created during a mobile process. This paper takes backpackers’ travel in Sichuan-Tibet highway as a case, exploring the significance of graffiti as a spatial practice by combining mobile ethnography with multi-sited ethnography. We interviewed 20 backpackers including hikers, riders, hitchhikers and 2 hostel owners. Also, graffiti on walls of hostels and restaurants, on the roadside railings, monuments and scenic spots was collected. This study finds that graffiti practice makes the Sichuan-Tibet highway and nodes along the way such as hostels become the witness of backpackers' journeys and even their lives. The Sichuan-Tibet highway originally as the instrumental and political space is rewritten into a private and emotional space. Because Tibet is thought to be holy by Han travelers, their travel to Tibet via this highway is regarded as pilgrimage to some extent. The difficulties during the journey due to the dangerous road conditions is constantly compared to difficulties in life by travelers. Lots of graffiti record travelers’ experiences and feelings during the journey. Moreover, graffiti practice contributes to the formation of a post-modern “neo-tribe”, as Michel Maffesoli suggested. Backpackers interact with each other via graffiti although they are not going through these spaces at the same time. Graffiti can be perceived as a language of the backpacking group and they “talked” to each other through making comments’ on others’ texts. As a protocol, backpackers avoid overlapping others’ text. It becomes a game of backpackers to compete for the space left over and they develop different strategies. Backpackers share their feelings, exchange jokes, and encourage each other through graffiti. As a result, backpackers’ graffiti reshapes the spatial meaning of Sichuan-Tibet highway and its nodes, and this activity also plays a crucial role in the formation of the unique travel culture of this highway.

The number of tourist attractions has been growing rapidly since the quality rating system of A-grade tourist attractions was implemented in China since 2001, and the spatial distribution is characterized by obvious expansion, agglomeration and regional differentiation. On the basis of the national A-grade tourist attractions in four time sections (2001, 2006, 2011 and 2016), the spatial and temporal evolutions of tourist attractions are analyzed by adopting GIS spatial analysis methods, such as standard deviation ellipse, kernel density estimation, and nearest neighbor indicator. The results indicate that: (1) the spatial pattern of A-grade tourist attractions presents a diffusion distribution and is highly consistent with the "Hu Huanyong Line"; the center of gravity migrated to the northeast by south in 2001-2016. (2) The agglomeration of A-grade tourist attractions scope expands; the agglomeration phenomenon becomes much more obvious. In 2001, the number of A-grade tourist attractions agglomeration areas was only 4; in 2006 and 2011, with the rapid growth, the number of agglomeration areas increased to 19 and 40, respectively; in 2016, the number increased to 62. (3) The agglomeration degree strengthens; the agglomeration degrees of Beijing-Tianjin-Hebei region and Yangtze River Delta are the highest. Among them, the kernel densities in Beijing and South Jiangsu are more than 100 per 100,000 square meters. (4) The gathering trend of high-grade (4A and 5A) tourist attractions are basically consistent with that of national A-grade tourist attractions. The study also discussed the agglomeration area of A-grade tourist attractions, which presents the characteristic such as the tourism resource dependence, and the dual drivers of supply and demand may be the reasons for A-grade tourist attractions agglomeration. In addition, the agglomeration area of A-grade tourist attractions had the core and edge structure with the similar distance between two adjacent kernel density levels. It is hereby that the concept of ‘tourist attraction cluster’ is put forward in order to further theoretical and systematic research on the spatial and temporal patterns of tourist attractions, and provide the scientific reference for the layout optimization of national tourism productivity and the development of the regional economy in China.

Spatially explicit reconstruction of historical grassland cover can provide significant data for studies on the global and regional environmental change. However, being subject to the attribute of study objective and materials for reconstruction, progresses were rarely made both in the estimates of grassland area and the reconstruction of spatial patterns. Based on a good understanding of the grassland change history across western China, we attempted to determine the potential distribution extent of grassland cover without land reclamation using remote sensing-derived land use data and potential vegetation data. Then by overlaying Chinese historical cropland data over a map of the potential distribution extent of grassland vegetation, we proposed a reconstruction method of historical grassland cover across western China. Subsequently, as a case study, grassland cover maps in Gansu, Ningxia, Qinghai, and Xinjiang provinces during AD 1661 to AD 1980 were complied using this approach. The results show that: (1) the grassland coverage across the case area was 40.87% without land reclamation. However, due to the expansion of land reclamation, the amount of grassland decreased continuously, especially over the past 300 years. (2) The total area of grassland across this region decreased from 110.86 million ha in 1661 to 103.14 million ha in 1980. And changes in grassland area went through three phases over this study period, including a sharp decrease between 1661 and 1724, a slow decrease between 1724 and 1873, and a rapid decrease between 1873 and 1980. The average annual losses of grassland area in the three stages were 47.6 thousand ha, 7.5 thousand ha, and 33.8 thousand ha, respectively. Spatially, the main areas of grassland reclamation gradually transferred from Gansu and Ningxia to Qinghai and Xinjiang during the study period. (3) Based on historical archives and remote sensing-derived grassland data in 1980, we evaluated the reliability of the reconstructed grassland cover. Evaluations suggest that the reconstruction results captured the amounts and spatial distribution patterns of historical grassland cover well. Our methods can be used for the long-term reconstruction of grassland cover across western China.

As a fundamental component in water circulation, the spatio-temporal pattern of precipitation is critical for terrestrial hydrological cycle simulation. The satellite-based precipitation can describe the spatial pattern of precipitation properly, but the relatively low spatial resolution of the product limited its application in terrestrial hydrological cycle simulation. By taking Taihang Mountains as an example, based on the relationship between precipitation, altitude and NDVI (Normalized Difference Vegetation Index), the monthly GPM (Global Precipitation Measurement Mission) data from 2014 to 2016 are disaggregated to 1-km resolution with a GWRDL model (Geographically Weighted Regression Model coupled with Distributed Lagging). The results showed that with the aid of the altitude and NDVI, the GWRDL model could effectively downscale monthly GPM data. The spatial resolution of downscaled GPM data was increased by the GWRDL model, and the accuracy of the original GPM data was retained at the same time. Compared with precipitation downscaled by the Geographically Weighted Regression Model and Multiple Linear Regression Model, the precipitation downscaled by GWRDL model has highest coefficients of determination (R²), lowest root mean square error (RMSE) and lowest mean absolute error (MAE) with the observed data, indicating that using NDVI in other months as explanatory variable is better than that using NDVI in current month, and this practice improved the downscaling algorithm and highlighted the accuracy of downscaled precipitation. Because the relationship between precipitation and NDVI was closer in the next spring than that in winter, using NDVI in the following 2-3 months (NDVI in next spring) as an explanatory variable in GWRDL model can improve precipitation downscaling precision in winter. Although the GWRDL model, which gives a consideration of time lagging of NDVI, has a better performance than GWR model in winter, it is more suitable for precipitation downscaling in vegetation growing stage than in winter. Compared with original GPM data, the coefficients of determination between downscaled GPM data and observed precipitation was averagely increased by 0.02 with GWRDL model in vegetation growing stage (April to October), which is higher than that in winter (0.002). Therefore, we suggest that the GWRDL model should be used in GPM downscaling in vegetation growing seasons.

Child trafficking is a long-term criminal phenomenon in China. As one of the serious crimes and complex social problems, it has attracted extensive attention from the public and academic community. Since related studies from the perspective of crime geography started late and most of these studies worked on the pattern of the country, it is urgent to concentrate on high-risk areas and key groups. In this research, we take Guizhou province, one of the major origins of child trafficking in China, as the study area. We use a series of techniques including text analysis, mathematical statistics, and spatial analysis to examine the social-demographic characteristics, spatio-temporal patterns, and influencing factors of child trafficking in Guizhou. Major findings include: (1) more males than females are trafficked in Guizhou, with males aged 1-6 as the main group, followed by aged 12-15, aged 0 and aged 7-11. The trafficked children from Guizhou to other provinces, mainly flow from urban to rural areas while children flow into Guizhou mainly from rural to urban areas. The cross-flow between urban and rural areas is the highest crime flow mode. (2) From 1944 to 2018, the crimes of child trafficking in Guizhou can be divided into three stages: extremely low growth stage (from 1944 to 1984), high fluctuation growth stage (from 1985 to 2000), and low and medium growth stage (from 2001 to 2018). At the same time, the summer half-year and the weekday witness higher incidences of child trafficking months and weeks. (3) At the city level, the crime is predominantly found in the northwestern half of Guizhou, especially in Guiyang city. At the county level, the crime shows a pattern of divergent decline in Guiyang and its surrounding areas. At the site level, it is more common in the open space where people move frequently. The overall crime path is “from Guizhou to the eastern regions of China” and “from Sichuan and Yunnan into Guizhou”, and there is an intercity flow in Guizhou. (4) The crime of child trafficking in Guizhou is mainly affected by the natural population change, family planing policy, floating population, and economic development level.