Analyzing spatial patterns of urban carbon metabolism and its response to change of urban size: A case of the Yangtze River Delta, China

Rapid urbanization with land use and cover change (LUCC)is making a substantially increasing contribution to global carbon emissions. Understanding the spatial processes and transitions mechanism of urban carbon metabolism system by LUCC could help local governments in regional spatial planning. Taking 13 cities in the Yangtze River Delta of China as examples, we quantitatively analyzed and mapped the spatial processes of urban carbon metabolism by LUCC from 1995 to 2015 in the region and investigated the relationships between urban size growth and urban carbon metabolism rate by LUCC (M_LUCC)using panel data regression analysis. A higher M_LUCC showed a larger negative impact on the urban carbon metabolism system by per unit area of land use change. We found that the highest negative carbon transitions were shifted from Shanghai to cities in the South Jiangsu Province. And the dominant negative carbon transitions and positive ones came from land use transfer into and out the industrial land and transportation land. The results of the panel model regression analysis showed the growths of urban population and land both correlated positively with M_LUCC. Further, we controlled the economic growth and urban form changes on the relationship between urban size growth and M_LUCC, and the results suggested both the benefits from compromising economic growth and optimizing urban form were overshadowed by the negative impact of urban size growth. The study provided a robust methodology for assessing urban carbon metabolism and provided new insights into land use controls to develop low carbon cities.