Analyzing accessibility and urban spatial connection of the Silk Road Economic Belt is the basis for implementing the strategy of the Silk Road Economic Belt and facilitating cooperation and achieving mutual benefits of the region along the economic belt. Based on GIS spatial analysis technology, the spatial pattern of raster grid accessibility for the Silk Road Economic Belt is studied and the states of urban spatial relation are simulated using land transportation network in this research. The result shows that the spatial distribution of urban accessibility in the Silk Road Economic Belt presents clear spatial characteristics of aggregated distribution along the main corridors. Average accessibility of urban nodes as measured by travel time is 16.25 hours, and the areas accessible within 2 hours occupies 10.6% of the total area. Most of the areas with the lowest accessibility are found in the margins of the deserts, with the worst accessibility of 171 hours. Xi'an as the gateway city connects the five provinces of Northwest China and other countries, regions, and cities of the Silk Road Economic Belt. The spatial connections of Central Asian countries within e national boundaries and with cities outside are relatively weak. The Silk Road Economic Belt is forming four main axes. In the future strategic development of the Silk Road Economic Belt, it should consider to implement a "point-axis" growth structure to drive the development of corridors and central cities (dense urban area).
This research measured road transport superiority degree of the 680 counties (county-level cities and districts) in the 14 concentrated contiguous severe poverty areas of China in 2012 by integrating the indices of road network density, city proximity, and weighted average travel time, and made a comprehensive evaluation of their spatial patterns. It then chose the optimal model of SEM to explore the impact of road transport superiority degree on economic growth. The results show that: (1) With regard to road network density, city proximity, and weighted average travel time, there is a large difference among the 680 counties (county-level cities and districts) in the 14 concentrated contiguous severe poverty areas. Road transport superiority degree of the 680 counties (county-level cities and districts) presents a right-skewed normal distribution. (2) Road transport superiority degree is divided into four classes from good to bad. The first (best) class includes the Dabie Mountain area, Luoxiao Mountain area, Lvliang Mountain area, and Yanshan-Taihang Mountain area; the second class includes the Qinba Mountain area, Liupan Mountain area, Wuling Mountain area, Wumeng Mountain area, Dian-Gui-Qian Rocky Desertification area; the third class contains the western Yunnan border mountain areas, the Great Khingan South Mountain area, and the Tibetan area in four provinces; the rest of the 14 concentrated contiguous severe poverty areas belong to the fourth (worse) class, which includes Tibet and three prefectures of southern Xinjiang. (3) The fitness of the SEM model is superior compared to the OLS model and the SLM model. The impact of road transport superiority degree on economic growth is clearly significant: every increase of one percentage point in road transport superiority degree has a contribution of 0.193% on economic growth. Therefore improving road network density can enhance road transport superiority degree and promote local and regional economic growth.
Study on urban economic network benefits from the rapid development of complex network research to depict the spatial pattern of urban economic activities more accurately. But a large number of studies still follow the spatial structure of urban system approach, which concerns competition, ranking, and centrality but not cooperation, equality, and connectivity. This article divides the urban economic network research into three stages with regard to complexity theory: (1) initial and theoretical development stage before the 1940s; (2) innovation and breakthrough stage from the 1950s to the 1990s; and (3) diversification and prosperity stage since the beginning of the 21st century. The current focus areas of urban economic network study cover topological structure and spatial coupling of urban economic network, connectivity measurement and quality evaluation in world city network, dynamic effect of urban economic network structure, and safety control and functional optimization in the future. It is very important to pay close attention to data integration and mining in the age of big data to build the research framework of urban economic network.
Based on land use in the residential quarter and housing survey data and using residential quarter as the basic spatial unit, this study examines spatial differences of residential quarter floor area ratio using GIS technology and the Theil index model. It first calculates the residential quarter floor area ratio in GIS, then divides residential quarter floor area ratio into 7 classes and generates a spatial distribution map and a contour map in GIS. It then uses the Theil index to calculate the spatial differentiation index of residential quarter floor area ratio, and analyzes the causes. The results indicate that: (1) Spatial distribution of floor area ratio classes in the study area presents an overall fragmented pattern. Residential quarters with the same floor area ratio are clustered in small areas, and similar classes are interspersed. (2) Spatial difference index of residential quarter floor area ratio in Dalian is low. Maximal spatial difference index values are found in residential quarters with extremely low and high floor area ratios. The maximum and minimum spatial difference index values occurred in the Zhongshan and Ganjingzi Districts. Differences within each of the four districts are far greater than the regional differences between these districts and this is a remarkable characteristic of spatial difference index values of residential quarter floor area ratio in Dalian. (3) The main causes of the spatial differences of residential quarter floor area ratio in Dalian is the location of residential quarters in the city and housing attributes that determined the types of the housing; constraints imposed on residential quarter construction by the topography of the city; direction from residential land use planning standard for the city, and the effect of land price.
With the rapid development and widespread application of network technology, online shopping is having profound impact on the economy and lifestyle of urban residents. Group-shopping based on network platform is emerging in recent years. Experiential online group-buying have had significant impact on the geographic patterns of consumption because of its space limitations of services. Using comprehensive scale index, development level index, concentration index, and spatial mismatch index, this study takes China’s 30 provincial cities and municipalities as objects to examine the spatial pattern and spatial mismatch of experiential online group-buying market based on the 360 group-buying navigation website. The results show that: (1) The scale of experiential online group-buying commodities in these provincial cities and municipalities is unbalanced, and the development of market is led by the eastern developed cities, as well as by growth pole cities of the western region. (2) The development of experiential online group-buying market in provincial cities and municipalities is mostly in either small scale and low level or large scale and high level, showing a clear polarized situation. (3) Economic development is the fundamental driving factor of the expansion of experiential online group-buying market. Consumption potential scale of online retail market, scale of internet infrastructure, size of the user group of internet and level of development of the internet also have significant influences on the expansion of the market scale. (4) The spatial mismatch between experiential online group-buying market and consumption demand in China is small, but the spatial mismatch between experiential online group-buying market and purchasing power is large. Cities that have too big or too small experiential online group-buying markets have made a significant contribution to this spatial mismatch.
With the rapid development of high-speed rail (HSR) in the world, accessibility by high-speed railway has become a important topic in accessibility research. The implementation of the Xiamen-Shenzhen HSR in southern-east China offers a new option for travelers, but also influences or generates the redistribution of demographic and economic activities. This study applies an integrated method to explore the regional spatiotemporal accessibility on a Geographical Information System (GIS) platform. This method makes full use of the advantages of network analysis and cost-weighted raster analysis, and removes the limitations existed in current accessibility analysis. The research area covers seven cities in eastern Guangdong Province due to the limited availability of data. Results are as follows: (1) The Xiamen-Shenzhen HSR condenses spatial and temporal distances and improves the regional accessibility significantly. Regional average accessibility time was 1.652 hours before the operation of the rail, and this accessibility time is improved to 1.418 hour after the operation, with an increase of 14.16%. (2) The spatial structure of the accessibility change presents an "island" or "banding" shape. At the station level, the rail creates concentric rings of accessibility change, while at the regional level accessibility change are along the HSR corridor. (3) The HSR substantially modifies the map of regional accessibility by reducing travel time and brings the peripheral areas closer to the central city (Shenzhen). However, it may also produce an increase of the core-periphery imbalances. The HSR also has a potential influence on the industrial upgrading and collaboration with a shrinking distance. Finally, the stations in the core cities are the chief beneficiaries of the new spatial order. The stimulation to development around stations in small or medium cities will be a long-term process.
Poverty-stricken mountainous areas often experience a severe shortage of medical resources, with uneven distribution and poor service capacity. This study uses the modified two-step floating catchment area method to analyze the characteristics of spatial accessibility of medical services in Shizhu County, Chongqing Municipality, southwestern China. It explores factors affecting the spatial accessibility of medical services from a supply and demand perspective, aiming for providing decision support for the planning of medical resources space allocation of mountainous regions. The basic unit of analysis is natural villages. Results show that: (1) Overall, the spatial accessibility of medical services in Shizhu County is poor and below the average level in Chongqing Municipality. (2) Medical resources distribution is uneven and the spatial differentiation is very clear. High accessibility areas mainly concentrate in the low and middle mountain areas of Fangdou Mountain and Huangshui Town. Low accessibility areas mainly concentrate in the high mountainous areas of northern Qiyao Mountain and middle mountain areas of southern Qiyao Mountain. The difference in accessibility is significant. (3) Scale and grade of hospitals and grade and density of roads have certain effect on accessibility: Accessibility is generally good in places near the county seat and have a dense road network. (4) Accessibility is high in places of dense road network. (5) With the increase of the distance impedance, accessibility gets better within the county but deteriorates at the peripherals of the villages and towns. The range of accessibility is lower, differentiation of spatial accessibility of medical services shrink, and the influences of the villages and towns with sufficient medical resources on accessibility of surrounding villages and towns increase.
Nitrogen (N) cycle has been poorly characterized in urban ecosystems. In China, urbanization is an important process that alters urban ecosystem and urban nitrogen biogeochemical cycle. Human activities have more than doubled the nitrogen inputs to urbanized areas, and the sources, magnitude, spatiotemporal patterns, and drivers of N fluxes have been mediated by human activities. The imbalance of nitrogen cycle has far exceeded the safe limits of urban sustainable development in some urban areas in China. The urbanized areas are facing a series of environmental problems induced by excessive emission and deposition of reactive nitrogen. Urban smog is becoming very serious in a large number of Chinese cities. However, owing to the limited knowledge on the role of humans in the N biogeochemical cycle and the complexity and uncertainty of urban ecosystems, ecological research of nitrogen emission, deposition, transformation, removal, and retention in urban areas is relatively weak. Thus, comprehensively quantifying changes of nitrogen cycle in urbanized areas and understanding the effects of human activities, such as urbanization and economic development, on the variations of reactive nitrogen fluxes, have been a crucial topic in urban ecological research. This article reviews the state-of-the-art research in this field on the basis of comparison and analysis of Chinese and international studies. The problems exist in current research were summarized and future areas of research aiming at a much improved understanding of the scope of the anthropogenic N problem are discussed. With serious nitrogen pollution and environmental effects in urban areas, it is essential to carry out a long-term study of nitrogen flux and nitrogen budget to investigate the problem of nitrogen imbalance. It is necessary to think beyond the control of pollutant emissions and approach the issue and solution from an urban planning perspective and conduct comprehensive studies to understand the variation of nitrogen input and output trends and driving mechanisms.
The spatial characteristics of Regional Plan Environmental Impact Assessment (RPEIA) determine its sensitivity to spatial scale. Spatial scale of RPEIA is not only a technical issue, but also related to the important questions that RPEIA needs to answer and elaborate. This article discusses the relationship between spatial scale and basic data, the screening of significant environmental factors, and evaluation indicators, as well as the relationship between spatial scale and prediction of atmospheric environmental impact. It then examines two cases: the RPEIA of
Understanding the complexity of spatiotemporal variations of sudden environmental pollution incidents and quantifying the contribution of their driving factors are important for effective environmental management in China. In this study, we analyzed the spatiotemporal patterns of sudden environmental pollution incidents and influencing factors in China for the period of 1995-2012 based on the Exploratory Spatial Data Analysis (ESDA) and Spatial Econometric Panel Model. The results indicate that: the frequency of environmental pollution incidents was gradually declining after the initial fluctuating growth and the high-frequency areas were mainly concentrated in eastern and southwestern China; ESDA analysis revealed that China's environmental pollution incidents were random distributed from 1995 to 2000 and agglomerated after 2001; in recent years the high-frequency area focused on the Pan-Yangtze River Delta region; the high-frequency center moved rapidly in 1998-2001 and 2004-2007 as a consequence of the regional industrial transfer and high pollution discharge pressure, toward southwest and northeast. Environmental pollution incident was different from pollutant emissions and is not an inevitable outcome of economic development. It is mainly related to the level of pollution control, government environmental supervision ability, spatial effect, and other factors. As one of the most important factors influencing environmental pollution incidents, spatial effect mainly included the spatial proximity effect and spillover effect. In order to control environmental pollution incidents effectively, the government should formulate joint transboundary pollution incidents emergency response mechanisms within regions based on regional pollution diffusion and transfer.
Desertification is a serious problem worldwide that has environmental and socioeconomic consequences. Desertification research has important significance for protecting the environment and for regional sustainable development. Based on an examination of the connotation of desertification we suggest that desertification not only are caused by human disturbance superimposing on climatic drought in dryland areas of the north, but also can be a result of extreme land degradation due to soil erosion superimposing on physical drought effect in southern humid areas. This study compared different aspects of the desertification processes in dry and humid areas, including material base, climatic conditions, influencing factors, formation forces, core functions, and land surface processes. Finally, we used red beds area of southern China as an example to analyze red beds land degradation by combining on-the-spot investigation and vegetation cover (VFC) data derived from Landsat TM images in 1992-2013. The results show that under the impact of repeated human interference and natural factors, there is a clear trend of vegetation change, topsoil loss, and rock weathering, which produce desert-like landscape. The degradation process in red beds is similar to the Karst rocky desertification and land degradation of red soil in hilly areas, but whether this type of extreme land degradation that took place in the humid area of southern China is "desertification" needs further studying.
Existence of impervious surface areas (ISA) in cities strongly influences the physical and chemical characteristics of regional soil, therefore, has profound impact on ecosystem carbon cycle at multiple scales. However, due to the inaccessibility of soil sample beneath urban ISA, we know little about the biochemical properties and distribution pattern as well as the importance of soil organic carbon under urban ISA (SOCISA). To clarify this issue, 100-cm-depth soil profiles from 27 paired ISA and pervious surface areas (PSA) sites in northern Tianshan urban cluster in a dryland environment of northwestern China were taken. In order to estimate total soil carbon storage, urban land cover was retrieved from cloud-free Landsat8 images. Based on the data of land cover area and SOC, the soil carbon storage of this urban cluster was calculated. (1) averaged 100-cm-depth SOCISA of the northern Tianshan urban cluster is 5.74±0.39 kgC·m-2, which is significantly lower than the paired soil organic carbon of PSA (SOCPSA) of 8.69±0.75 kgC·m-2, about 52% of the latter (p<0.01); averaged soil bulk density (BD) under ISA BDISA=1.58±0.02 g·cm-3, which is significantly higher than its paired BD of PSA of 1.51±0.02 g·cm-3, about 5% of the latter (p<0.01). (2) SOC and BD of both ISA and PSA declines with depth. The results of linear fitting between SOC, BD, and depth show that SOCISA and BDISA have significantly declining trends, however, SOCPSA and BDPSA does not show such clear trend. In addition, SOCPSA at the 60~100 cm soil layers is significantly higher than SOCISA but there is no stable correlation between them. (3) Carbon storage hidden under ISA of northern Tianshan urban cluster is 68% of the total urban carbon storage and for individual cities this percentage is higher than 50%, therefore, SOCISA is the main part of the urban SOC storage. By revealing the SOCISA and its distribution, this study can facilitate the understanding of biochemical characteristics of soils beneath urban ISA, which is significance for estimating carbon cycling in both urban and global ecosystems.
