资源环境科技发展态势分析平台

Urban expansion and renewal are one of the major drivers affecting urban landscapes worldwide. Considerable research has been conducted to understand how urban greenspace (UG) changes in response to urbanization at various scales from individual patches to landscapes. However, most of these studies have been conducted at a single scale, and little is known from a multiple scale perspective. Here, we present a multi-scale analytical framework to quantify the spatial pattern of greenspace and its change by integrating rank-size distribution, urban–rural gradient analysis and hotspots analysis. We applied this framework to nine major Chinese cities using 2.5 m resolution Advanced Land Observation Satellite and Systeme Probatoire d'Observation de la Terre imagery captured in 2005 and 2010. We found the multi-scale assessment provides integrated and synthesized information about the dynamics of UG that would otherwise be missed. First, the hotspots analysis revealed dramatic change in UG for all the nine cities, and such change tended to be spatially clustered. Second, the spatial heterogeneity of UG decreased from 2005 to 2010 for all the cities as a result of the increase of UG in urban core areas and loss of UG in the urban periphery, resulting in landscape homogenization along the urban–rural gradient. Third, substantial loss of UG co-occurred with densification of urban land development, indicating potential adverse impacts of compact city on urban greenery. Infill development became dominant, with percentage ranging from 52.7% in Shanghai to 90.6% in Nanjing, resulting in more compact urban form. This study underscores the importance of a multi-scale perspective on understanding the spatial distribution of UG and its change, and its response to urban development.