It is widely recognized that brownfield regeneration to green space is a sustainable form of urban development. However, it is essential to choose those brownfields that have the greatest potential to be integrated into urban green infrastructure (GI). This paper addresses how to quantitatively assess the ecological potential of coal mining brownfields at the city level, and looks at how these brownfields can be best adapted to enhance the GI system. Taking Xuzhou as an example, an ecological potential assessment method for brownfield regeneration to green space is established considering both its ecological importance and the capacity of maintaining GI connectivity. The results show that more than half of the coal mining brownfields have relatively higher ecological importance values, and only four patches play an important role in maintaining GI connectivity. The final ecological potential values of brownfield regeneration to green space are obtained by overlaying the values of ecological importance and the capacity values of maintaining GI connectivity. Then, all the brownfields are divided into five groups according to their ecological potential values, which are significantly different in each group. Around 51.35% of the brownfields have a high or very high potential for restoration to GI, which are distributed in the southeastern part of the western mining area and the central part of the eastern mining area. The presented method can assist reclamation scientists and urban planners in decision making based on quantitative analysis.

Exploring the complex effects of landscape patterns on ecosystem services (ESs) has become increasingly important in offering scientific support for effective spatial planning and ecosystem management. However, there is a particular lack of research on the nonlinear effects of landscape patterns on ESs and scale dependence. Taking Huainan City (in China) as a case study, this study adopted the InVEST model to estimate four key ESs including carbon storage (CS), habitat quality (HQ), nitrogen export (NE), and water yield (WY). Then, we calculated the selected landscape metrics at multiple spatial scales. Furthermore, the gradient boosting decision tree (GBDT) model was developed to investigate the relative importance of landscape metrics in explaining ESs and their nonlinear interrelation. The results indicated that most of the selected landscape metrics were significantly correlated with ESs. The GBDT model, which can explore nonlinear relationships, performed better than the linear regression model in explaining the variations in ESs. The landscape-level metrics of the Shannon’s diversity index (SHDI) and the contagion index (CONTAG) and the class-level metrics of the aggregation index (AI) and edge density (ED) were the most important variables that influenced ESs. The landscape metrics affected ESs within a certain range, and the nonlinear effects varied with scale.

In the past 40 years, China has undergone a rapid urbanization process which has led to a significant contradiction between the desire to develop modern urban spaces and the need to protect historic urban sites. Urban construction has brought not only the destruction of the physical space of the historic urban sites, but also the fragmentation of the natural landscape and its structural disconnection to the historic urban landscape. Ancient Chinese planners had their own thoughts regarding urban construction and the specific patterns of the urban landscape. The urban landscape of Chinese historic cities focuses predominantly on the structural relationship to its neighborhood. This paper aims to explore the value and character of the historic landscape of the ancient city, finding the key causes of its decline in the process of urbanization. The World Cultural Heritage city Pingyao is taken as a case study. Firstly, an analysis of its historical spatial structure and urban planning ideas of the ancient city of Pingyao using ancient maps and historical documents is presented. Then, a quantitative analysis of the urban space expansion in Pingyao city from 1989 to 2016 is conducted and its land use structure further analyzed. Additionally, four editions of the urban master plan in Pingyao have comprehensively shown that modern urban construction and planning tend to focus more on urban economic functions and social needs. In contrast, ancient urban planning relied on the spatial connection between urban space and its natural environment to construct a higher urban cultural connotation. As a result, the different development mode between modern urbanization and construction of ancient cities could be the key reason for the decline of spatial structure and landscape fragmentation of historical cities in China. With respect to the experience and thoughts of Pingyao’s ancient urban planning and construction, technical ideas and suggestions are put forward as reference in future spatial planning for Pingyao’s urban development and cultural protection. Our findings have been incorporated into the relevant sections of the spatial planning of Pingyao.