Understanding the dynamic of greenspace in the urbanized area of Beijing based on high resolution satellite images

Urban greenspace plays an essential role in urban ecosystem and highly contributes to the welfare of urban residents. Understanding the dynamics of greenspace is crucial for its planning and management. Previous studies have largely focused on changes in greenspace in urbanizing regions, using medium resolution remotely sensed data. However, the changes of greenspace in urbanized areas need to be accurately quantified based on high spatial resolution images because they are directly related to human health and well-being. This paper aims to enhance the understanding on dynamics of greenspace within well-developed areas of the city, using Beijing City, China as a case study. Using high spatial resolution remotely sensed imagery, we analyzed the spatial pattern of greenspace and its change on two scales: (1) the entire area within the 5th ring road, and (2) in 4 belts from urban center to fringe. We found urban greenspace was very dynamic. The proportion of urban greenspace increased by 5.45%, or 36.3 km2 in size from 2005 to 2009. The amounts of gain and loss of greenspace were 69 km2 and 32.7 km2, respectively, or 10.36% and 4.91% of the entire study area. Because of the very limited lands for greening in urbanized areas, the new patches of greenspace were generally small, with the mean patch size of 676.31 m2. However, those small patches enhanced the connectivity and continuity of urban greenspace. In addition, we found the differences in configuration of greenspace patches across the 4 belts were greater than the differences in total percent cover, indicating that compared to percent coverage, greenspace configuration may be more influenced by the development age.