Assessment of water-related ecosystem services based on multi-scenario land use changes: focusing on the Poyang Lake Basin of southern China

A scientific understanding of the trends of water-related ecosystem services (WESs) under different scenarios is crucial to improving WESs and maintaining ecological security. However, there is a lack of high-resolution land use simulation and assessment of WESs under the SSP-RCP scenarios, and the impacts of different land-use change (LUC) on WESs are not clear. This study focused on the Poyang Lake Basin (PYLB), utilizing the SSPRCP scenarios, the PLUS model and the InVEST model to explore the dynamic changes of land use and WESs historically and in the future, and to reveal the impacts of specific LUC on WESs from 2000 to 2020. The results demonstrated that: (1) The forest land increased under both SSP1-2.6 and SSP2-4.5 scenarios but increased first and then decreased under SSP5-8.5 scenarios; Cropland increased significantly under SSP5-8.5 scenarios, and the construction land showed an expansion trend under the three scenarios. (2) From 2000 to 2020, only the water purification capacity decreased, while the rest of the WESs increased. Under the SSP1-2.6 scenario, the overall benefits of the WESs in the PYLB were the highest. (3) Between 2000 and 2020, deforestation in the PYLB brought about the greatest increase in the water yield (+9.06 x 108 m3). The increase in the construction land brought about the most water conservation loss (-18.19 x 108 m3). Additionally, the forest expansion and cropland reduction brought about the largest increase in soil retention (+3.94 x 105 t and +4.79 x 105 t) and enhanced water purification, and the opposite was true for deforestation. The conclusions can provide an important basis for the ecological protection and high-quality development of the PYLB.