How the landscape features of urban green space impact seasonal land surface temperatures at a city-block-scale: An urban heat island study in Beijing, China

Abstract

Urban greening has been widely regarded as one of the most effective strategies for alleviating the risk of urban heat island (UHI). In this study, the metropolitan region of Beijing in China, was chosen as the study area. We used urban blocks as the special units for spatial analysis, and 17 landscape factors, including both landscape composition and configuration metrics, were chosen as the explanation variables for seasonal land surface temperature (LST). Based on these, we examined the potential differences in the relationship between urban LST and the landscape characteristics of urban green space (UGS) in different seasons and UGS gradients. Our results confirmed the significant cooling effect by UGS at a city-block-scale. However, the roles of UGS landscape composition and configuration on impacting LST varied in different seasons and UGS gradients. Generally, the cooling effect of UGS is more significant in locations with warmer climate or lower UGS coverage, and the landscape composition characteristics of UGS had a dominant effect on the variation of LST. On the contrary, in cold seasons or higher UGS ratios, the landscape configuration characteristics of UGS, such as the edge density of urban forest patches, would predominantly function to alleviate UHI than landscape composition in urban blocks. Moreover, the geometry features of urban blocks were also found to have a certain influence on LST. These findings demonstrated that the influence of UGS landscape features on urban surface thermal environment is very complex at city-block-scale. Therefore, for UHI mitigation, a prerequisite for multifactor analysis must be taken into consideration during the implementation of urban greening.