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With urban population growing and urban sprawling, urban ecological environment problems appear. Study on spatiotemporal characteristics of urban sprawl and its impact on ecological environment is useful for ecological civilization construction. Although a lot of work has been conducted on urban sprawl and its impact on ecological environment, resolution of images to extract urban boundary was relatively coarse and most studies only focused on certain indicators of ecological environment, rather than comprehensive evaluation of urban ecological environmental impact. In this study, high-resolution remote sensing images of Beijing from aerial photography in 2002 and 2013 respectively are employed to extract urban boundary with manual interpretation. Fractional Vegetation Coverage (FVC), Water Density (WD), Impervious Surfaces Coverage (ISC), Net Primary Production (NPP), and Land Surface Temperature (LST) are adopted to represent ecological environment. The ecological environment indicators are measured with some general algorithms by combining Landsat images, GIS data and metrological data of 243 day, 2001 and 244 day, 2013. In order to evaluate the impact of urban sprawl on ecological environment, pseudo changes due to metrological variation and other noise in this time period are removed after images calibration. The impact of urban sprawl on ecological environment is evaluated at different scales of urban extent, Beijing ring road and watershed. Results show that Beijing had been undergoing a rapid urbanization from 2002 to 2013, with urban area increase from 600 square kilometres to 987 square kilometres. All ecological environment indicators except LST became terrible in urban sprawl region, with carbon reduction of approximate 40508 tons. The Beiyun River watershed of Beijing degraded seriously since ISC increased to 0.59. Gratifyingly, ecological environment indicators including NDVI, NPP, and LST inside of 4th Ring Road became well. [ABSTRACT FROM AUTHOR]

The widespread development of gated communities has generated much concern over urban fragmentation and social segregation. The social division and segregation between residents inside and outside urban enclaves exist not only in their residential spaces, but also in their values, social relations, and daily lives. In this study, it is argued that sociospatial segregation research should pay more attention to individuals' actual usage of urban space in their daily lives. By examining the activity space of the residents from different types of neighborhoods, a spatiotemporal approach to studying sociospatial segregation in Beijing, China is described. Significant differences are found in the usage of time and space between residents inside and outside the so-called privileged enclaves. Their activity spaces are found to vary significantly in terms of extensity, intensity, and exclusivity. The study suggests that the fragmentation of urban space is the result not only of residential segregation, but also of how different social groups spend their time and use urban space. [ABSTRACT FROM AUTHOR]