Exploring the differences of ecosystem service values in different functional areas of metropolitan areas

Exploring the differences of ecosystem service values (ESV) in different functional areas is the basis for imple-menting differentiated ecological management in metropolitan areas. In this study, a general evaluation framework was first established to explore the differences of ESV in different functional areas of metropolitan areas. Then, taking Nanjing metropolitan area as a typical case, the land use transfer matrix and equivalent factor method were used to evaluate land use changes and ESV in different functional areas (moderate development area, key development area and optimization improvement area). Finally, spatial autocorrelation analysis, hotspot analysis and one-way analysis of variance were adopted to explore the spatial agglomeration charac-teristics, distribution of hotspots and cold spots and significant differences of ESV in different functional areas. The results showed that the expansion of developed land and degradation of ecological land occurred in different functional areas, especially in the optimization improvement area, which resulted in a significant decrease of ESV in different functional areas. The ESV of the three functional areas showed spatial positive correlation, but the distribution of hotspots and cold spots was different in different functional areas. The one-way analysis of variance found that optimization improvement area displayed significant differences in the values of four ecosystem service types with those of other functional areas, but there were no significant differences between moderate development area and key development area. In addition, the ecological function area with clear boundary was identified, which was mainly composed of the northern water network area (Hongze, Jinhu, Gaoyou) and the southern hilly area (Ningguo, Jixi, Jingde and Guangde). Therefore, differential ecological management measures such as green space construction in the optimization improvement area and ecological compensation mechanism in the moderate development area were formulated to promote the sustainable development of metropolitan ecosystems. This study can also provide reference for exploring the differences of ESV in different functional areas of other metropolitan areas within and beyond China.