Urban shrinkage has become a topic of major concern to scholars of geography and urban science. However, the methods of identifying urban shrinkage and growth have mostly focused on traditional statistical methods, and studies based on nighttime light (NTL) data are rare. Here, we use the NTL data for 56 months from 2012 to 2019 obtained by the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar Orbiting Partnership (NPP) to identify the shrinkage and growth patterns of Yichun in China, by calculating the slope of the NTL radiance value after denoising. At the same time, by combining high-resolution Google satellite images and traditional demographic data, we analyzed the shrinkage characteristics of Yichun. The results of the study confirmed the characteristics of partial shrinkage in China’s shrinking cities. In addition, the use of NPP-VIIRS NTL data was able to more accurately identify the urban shrinkage and growth patterns, and may also be seen to present a more objective picture of reality, thus providing a new perspective for studies of urban shrinkage.

By constructing an index system, this study analyzed the temporal and spatial characteristics of the economic resilience of 20 resource-based cities in northeast China after the financial crisis in 2008. On this basis, a mediation model was introduced to explore the mechanism of population shrinkage affecting economic resilience. The results show that: (a) from 2009 to 2019, the trend of the economic resilience of resource-based cities in northeast China was “ascending–descending–stable”. As time went by, the spatial difference of the economic resilience of resource-based cities gradually became obvious, indicating that the number of medium- and high-class cities was increasing. (b) By applying a correlation analysis, it was found that both a significant weak correlation and medium correlation existed between population shrinkage and economic resilience during the periods of 2011–2019 and 2013–2019. (c) Six mediation factors, namely industrial output, population consumption, resource dependence, urban innovation, cultural construction and environment quality, were chosen to apply the mediation model of population shrinkage affecting economic resilience. Among them, industrial output, population consumption, urban innovation, and cultural construction exerted a partial mediation effect on the process of population shrinkage affecting economic resilience, while the meditation effects of resource dependence and environment quality were not significant.

Urban shrinkage is currently spreading at global level. At the same time, the scale of urban shrinkage is not limited to urban agglomerations, metropolitan areas, or big cities, but begins to expand to a vast number of small towns. Over the years, the characteristics, models, and mechanisms of shrinkage in large cities have attracted the attention of scholars; however, the problem of shrinkage in small towns has not been fully discussed. In China, small towns are located at the margins of cities and are the first part of the countryside; hence, they are the link and the bridge between urban and rural areas, and a space carrier to solve the diseases of big cities and for rural rejuvenation as a whole. However, in the process of rapid urbanization, some small towns have experienced urban shrinkage, mainly through a decline in township enterprises and the deterioration of the living environment, which has restricted their role in coordinating the spatial support of urban and rural development. Therefore, a correct understanding of the shrinkage of small towns has considerable theoretical and practical guiding significance. We focused on the towns of the Jilin Province as the research unit, and combined township population, economy, land use, and employment indices to establish an urban shrinkage index, identifying the status, spatial distribution, and influencing factors of small towns shrinkage in the Jilin Province. Moreover, we analyzed the similarities and differences of small towns shrinkage between the Jilin Province and developed countries. The results show that small towns shrinkage in the Jilin Province shares similar characteristics with developed countries, as well as important differences in aspects such as population migration, low-level industrial structure, and administrative division adjustments.

As populations continue to be concentrated in cities, the world will become entirely urbanized, and urban space is undergoing a drastic evolution. Understanding the spatial pattern of conversion and expansion of functional urban land, in the context of rapid urbanization, helps us to grasp the trajectories of urban spatial evolution in greater depth from a theoretical and practical level. Using the ESRI ArcGIS 9.3 software platform, methods, such as overlay analysis, transition matrix, and kernel density estimation, were used in order to analyze the spatiotemporal characteristics of different types of functional urban land conversion and expansion in the central city of Changchun. The results show that different types of functional urban land were often expanded and replaced, and the urban spatial structure was constantly evolving. The conversion and expansion of functional urban land show similar characteristics to concentric zone and sector modes and show dynamic changes in different concentric circles and directions at different periods. Our method can accurately identify the different types of functional urban land, and also explore the evolutionary trajectory of urban spatial structure. This study will help to coordinate the development of different functional urban spaces and to optimize the urban spatial structure in the future.