The urbanization process, such as population growth and the expansion of roads, railways, residential areas, and industrial areas, causes severe landscape fragmentation and changes in the surface temperature balance, resulting in the heat island effect. This study used Landsat data to study the impact of landscape patterns on urban heat islands (UHIs) and temporal-spatial change characteristics. In addition, spatial correlation analysis was employed to detect the relationships between land surface temperature (LST) and landscape patterns. The results showed that the impervious surfaces landscape area increased significantly, and the Woodland landscape area increased. However, the bare land, cropland, and water body area decreased. The cohesion of cropland and woodland landscape in the suburb decreased, and there was a high degree of fragmentation. The difference between the contributions of the central city and suburbs to the whole region is narrowing, and the expansion of urban heat islands is shifting from the central city to the suburbs. The percentage of landscape index (PLAND) and the patch cohesion index (COHESION) of woodland, water body, and cropland were negatively correlated with LST. Meanwhile, the PLAND and COHESION of impervious surface and bare land were positively correlated with LST, and the splitting index (SPLIT) was the opposite of the PLAND and COHESION. The fragmentation of impervious surfaces and bare land landscapes reduces the UHI effect. Based on these results, countermeasures to mitigate the heat island effect are proposed. These measures will play an essential role in improving urban ecology and the environmental quality of human settlements.

Abstract:The state of the urban carbon cycle is an important indicator for managing fossil energy consumption and land resources and it is also a basis for the planning of urban eco-services and urban sustainable development. This paper aims to analyze the spatial distribution of the carbon cycle of the mono-centric cities, based on the von Thünen concentric ring theory, using the InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) model and an atmospheric diffusion model to assess the carbon sequestration capacity of land cover/use, to estimate carbon emissions, discuss influencing factors that determine changing trends in carbon sequestration capacity and to predict the changing law of the carbon sequestration eco-service spatial pattern based on scenario simulations. The results of this study show: (1) In Guang'an, the spatial distribution of the carbon cycle follows a concentric ring pattern. From the concentric ring pattern center, the first annular zone represents the carbon emissions, which lie at the concentric ring center; the second annular zone represents the carbon sequestration service; and the third annular zone represents stable carbon stock; (2) The structure of the concentric ring has not changed, but the spatial distribution of carbon sequestration and carbon density has changed due to fossil energy consumption and land cover/use change. From 2014 to 2016, the carbon emission zone shrunk, while the carbon sequestration service zone expanded and the carbon density increased-the increase of forest land is the main factor in the increase of carbon density; (3) The current carbon sequestration eco-service in Guang'an is not the best development condition. The planning of urban eco-service spatial patterns and land cover/use should consider the protection of cultivated and ecological areas at the same time. The results of this study can help the government implement spatial planning and regional policy interventions for land cover/use and eco-service.