Spatiotemporal Variation in the Yangtze River Delta Urban Agglomeration from 1980 to 2020 and Future Trends in Ecosystem Services

Over the past 40 years of reform and opening up, human activities in the Yangtze River Delta region have caused major changes in land use patterns and ecosystem functions. Clarifying the spatiotemporal change characteristics and future development trends of ecosystem service functions is the basis for rational land development and utilization. In this study, the InVEST model and the CASA model were used to calculate habitat quality, water conservation, carbon sequestration and oxygen release, and soil conservation ecosystem services in the Yangtze River Delta urban agglomeration from 1980 to 2020. The spatial pattern, change law, and future trend of these services were analyzed using the Theil–Sen median trend analysis, Mann–Kendall test, and Hurst index analysis. The results show that the four types of ecosystems in the Yangtze River Delta urban agglomeration (habitat quality, water conservation, carbon sequestration and oxygen release, and soil conservation) exhibited an overall spatial pattern of being high in the southwest mountainous area and low in the northeast plain, and the conversion from constructed to agriculture was the most frequent type of land conversion over the past 40 years. From 1980 to 2020, the average level of habitat quality showed a downward trend and is expected to continue to deteriorate in the future. Water conservation, carbon sequestration and oxygen release, and soil conservation showed a fluctuating upward trend, with the latter two primarily predicted to have a future trend of improvement. The changes in ecosystem services exhibit gradient effects and horizontal spatial differentiation. The decline in ecosystem service functions is more pronounced in the vicinity of large cities. It is thus necessary to accelerate the transformation of the economic development model, and abandon the extensive urbanization development model, and promote high-quality urbanization development on the basis of improving resource and environmental carrying capacities.