Quantitative estimation of 21st-century urban greenspace changes in Chinese populous cities.

Understanding the spatiotemporal changes of urban greenspace is a critical requirement for supporting urban planning and maintaining the function of urbanities. Although plenty of previous studies have attempted to estimate urban greenspace changes in China, there still remain shortcomings such as inconsistent surveying procedures and insufficient spatial resolution and city samples. Using cloud-free Landsat image composites in circa years 2000 and 2014, and Defense Meteorological Program Satellite Program's Operational Line-scan System (DMSP/OLS) nighttime lights dataset, we quantitatively estimated the urban greenspace changes regarding both administrative divisions and urban core boundaries across 98 Chinese populous cities. Results showed that a consistent decline of urban greenspace coverage was identified at both old and new urban areas in the majority of analyzed cities (i.e., 81.63% of cities regarding the administrative boundaries, and 86.73% of cities regarding the urban core boundaries). Partial correlation analysis also revealed that total urban greenspace area shrank as a linear function of the core urban expansion (R2 =0.28, P<0.001), and a significant correlation was confirmed between population change and urban greenspace change across those Chinese populous cities included in this study (R2 =0.11, P<0.001).