Impact Of Land Use Change On Water-Related Ecosystem Services In Ussuri River Basin And Their Trade-Offs Optimization

Land use change is a major driving factor affecting changes in ecosystem functions and ecological processes,and its changes significantly affect the supply and service capacity of regional water ecosystems.However,the relationships and dynamic change mechanisms between land use change and multiple water ecosystem services have not been well revealed,which to a certain extent limits the coordinated and healthy development of regional water ecosystem services.The Ussuri River basin is located in the border area between China and Russia,and it is an intermediate resting place for world-endangered migratory birds such as the Grus japonensis and the distribution area of world-endangered wildlife such as the Pamhera igrisalaica 、 Pamthera pardus orientalis,and the evolution of water ecosystem functions is of strategic importance for ecological conservation and sustainable development in Northeast Asia.Therefore,in this study,the Ussuri River basin was selected as the study area,and four water-related ecosystem services driven by land use change,water yield,water purification,soil retention,and food production,were assessed by the In VEST model and socioeconomic data based on fixed climate parameters,and water ecosystem services in the Ussuri River basin were assessed at multiple time scales by designing land use scenarios related to future development By designing land use scenarios related to future development,the evolution of ecosystem services and interrelationships in the Ussuri River basin was assessed at multiple time scales,and based on this,the best scenario for future sustainable development of the basin was explored.The main conclusions of this study are as follows:(1)From 2000 to 2018,the Ussuri River basin experienced a stage characterized by obvious indigenous expansion of farmland and shrinking of forestland,grassland and unused land.During the study period,the area of farmland(+7.66%)and Built-up land(+0.22%)continued to increase,the area of forestland(-3.20%)and unused land(-3.00%)continued to decrease,and the area of grassland and water area fluctuated.The area of grassland decreased by 1.58% and the area of water decreased by 0.11%.The transfer of land use types mainly occurred in the conversion of forest land and unused land to cultivated land and construction land.(2)Supply services improved in the Ussuri River basin during2000-2018,while regulating services deteriorated.During the study period,food production and water yield increased by 127.27% and 1.41% per unit area,respectively,while nitrogen export(+11.55%)and phosphorous export(+12.50%)continued to increase per unit area,water purification services continued to deteriorate in the basin,and soil retention status remained almost unchanged per unit area.(3)Correlation analysis shows that trade-offs between supply services(water yield,food production)and regulating services(water purification,soil retention)occur in the Ussuri River basin ecosystem services,while synergistic relationships occur within the supply and regulating services.(4)Based on the existing ecological problems,four land use development scenarios were designed,including agricultural development,forest buffer zone,returning farmland to forestland and integrated development.Among them,forest buffer zone was selected as the optimal scenario.Scenario analysis showed that the forest buffer zone scenario had the least negative impact on the supply of services while improving the regulation services in the Ussuri River basin,and the trade-off strength between ecosystem services decreased most,which was conducive to the sustainable development of watershed aquatic ecosystems.Therefore,the forest buffer zone scenario is selected as the best solution for the future development of the Ussuri River basin,which can help decision makers to achieve the relative balance of ecosystem services and achieve a win-win situation of economic development and ecological protection.This study reveals the driving effects of land use change on water ecosystem services,combines food security with ecological conservation,and provides a relatively complete framework for the assessment of water ecosystem service trade-offs,and the results can provide valuable supporting information for land use management in the Ussuri River basin to ensure the sustainable provision of food supply and other ecosystem services.