A Study On The Trade-offs And Synergies Of Ecosystem Services In The Nansi Lake Basin

In recent years,Nansihu Lake basin as a typical agricultural basin,serious ecological and environmental problem have occurred in most areas of the Nansihu Lake basin have occurred,such as soil erosion,non-point source pollution,loss of animal and plant habitat,led to the deterioration of water quality,the declining of Habitat Quality,the decreasing of biodiversity.These problems led to the degradation of various ecosystem services in the basin and seriously affected the ecological security of the basin.For better ecological management and protection in the future,it is essential to analyzed the spatio-temporal characteristics of ecosystem service and identify the trade-offs and synergies of multiple ecosystem services on different spatial scales.These questions were becoming the research hotpots of ecology,geography and other related disciplines.Therefore,the purpose of this research is to identify relationships of multiple ecosystem services on sub-watershed,county and point scales.In order to obtain more benefits in the ecosystem and maintain the sustainable development of the ecosystem,it is essential to seek a simulation scenario consistent with the characteristics of the study area.It is important to create a win-win situation on both sides of economic development and ecological protection.This study takes Nansihu Lake basin as an example,which is typical representative of the agricultural basin.Eight ecosystem services in Nansihu Lake basin were selected to simulate and evaluate by InVEST(Integrated Valuation of Ecosystem Services and Tradeoffs)model and the method of index calculation,since the reform and opening-up(1980-2018),which included crop production,aquatic production,water yield,water purification,sediment delivery ratio,carbon storage,biodiversity(habitat quality)and crop pollination.In this paper,the spatial distributions of eight ecosystem services were analyzed and the hotspots of each ecosystem services were identified by hot spot analysis in Arc GIS 10.2.Moreover,the spatial and temporal dynamics of relationships among eight ecosystem services were analyzed through correlation and principal component analyses via the correlation and principal component analyses.And further analyses were performed on different scales to the relations.Finally,the optimum allocation through scenario simulation was used to evaluate the comprehensive benefits of ecosystem services in the future,so as to provide scientific reference to the construction of ecological civilization in the Nansihu Lake basin.The main research contents and conclusions were as follows:(1)This paper analyzed the temporal and spatial distribution of eight ecosystem services in Nansihu Lake basin during 1980-2018.The provisioning services(such as crop production,aquatic production and water yield)was increasing from 1980 to2018,while regulating services(such as water purification,sediment delivery ratio and carbon storage)and supporting services(such as habitat quality and crop pollination)were decreasing during this periods.(2)This paper analyzed the relationship between hot spots of eight ecosystem services and land use distribution in the study area.The land use types in western and northern of the basin are mainly arable land,which the hot spots of crop production.The land use types in central of the basin is mainly water body,which hot spots of aquatic production.The land use types in eastern of the basin is mainly forest and grassland,which the hot spots of carbon storage,habitat quality and crop pollination.The areas with construction land suggested the hot spots of water yield and sediment delivery ratio.(3)This paper analyzed the relationship between trade-offs and synergies in the study region on three spatial scales.There were similarities and differences in relationships between sub-watershed,county and point scales.There was a significant trade-off relationship between water yield and water purification,as well as strong synergetic relationships between water purification and habitat quality,carbon storage and crop pollination occurred in the basin.Trade-offs mainly occurred between the provisioning services vs.the regulating services and provisioning services vs.the supporting services on sub-watershed and point scales.While on the county scale,there was a synergetic relationship between the provisioning services,regulating services and supporting services.(4)This paper evaluated the correlations and the overall benefits of ecosystem services under five simulated scenarios.The lower degree of trade-offs and the higher degree of synergies under the scenario of ecological protection for converting arable land to forest along the coastal zone.The overall benefit of the scenario of urban natural growth is the lowest(2.009).The scenario of ecological protection for converting arable land to forest along the coastal zone was the most favorable land use strategy for regulating ecosystem service capacity,the overall benefit is the largest(4.997).The future development of Nansihu Lake basin should be inclined to the scenario of ecological protection for converting arable land to forest along the coastal zone.