Ecosystem services supply and demand response to urbanization: A case study of the Pearl River Delta, China

The process of rapid urbanization makes our planet's natural ecosystems subject to strong interferences of different kinds of human activities, which affect the relationship between ecosystem services (ESs) supply and demand. Hence, unraveling the impact of urbanization on ESs supply and demand is urgently needed, especially in urban agglomerations. Previous case studies focused on the impact of land use change on ESs supply, and the relationship between urbanization and ESs supply and demand is still unclear. More precisely, the differences in the impact of population growth, economic development, and land use change on ES supply and demand remains unstudied. Taking the rapidly urbanized Pearl River Delta (PRD) urban agglomeration of China as an example, this study focused on four typical ESs, i.e. water yield, grain production, carbon sequestration and local recreation. The impact of urbanization on ESs supply and demand have been explored using regression analysis across regions characterized by different levels of urbanization. Furthermore, Random Forest, an algorithm based on decision tree, has been applied in order to assess the sensitivity of ESs supply and demand to urbanization. The results showed that, the total supply of various ESs decreased, while the total demand of the ESs increased, which resulted in an intensified spatial imbalance between ESs supply and demand from 2000 to 2015. In developed and developing urban areas, urbanization had no significant impact on ESs supply and demand, but urbanization had a significantly negative impact in rural areas. ESs supply and demand were most sensitive to (i) population density in developed urban areas, (ii) to population density, GDP density, and artificial land proportion in developing urban areas, and (iii) to artificial land proportion in rural areas. This study provides a basis for decision-making in the context of coordinated development of human and nature in rapidly urbanized areas.