The Research Of Trade-offs And Synergies Among Ecosystem Services Based On InVEST Model

Ecosystem services serve as a bridge between the ecosystem and the social system.As the intensified of contradictions between the people's ever-growing needs for a better life and the unbalanced development,the eco-environment is deteriorating,which has led to the degradation of ecosystem services.At the same time,it triggered regional and even global ecological problems.This makes ecosystem services more effective in maintaining ecological security,achieving sustainable development,and maintaining a high quality of human life.Therefore,what measures are taken to effectively manage the ecosystem,rationally allocate and use natural resources,maintain the sustainable supply of ecosystem services,enhance the overall efficiency of the ecosystem,to maximize the comprehensive benefits of natural resources,achieve sustainable development in the region,achieve "win-win" of human society and the ecosystem become one of the global problems need to solve.Selecting the Hehuang area with fragile ecological environment as the research area,using the ecosystem service evaluation model-In VEST model,and basing on the average annual precipitation,annual average potential evaporation,land use,and DEM data of the Hehuang area in 2015.In this paper,firstly a simulation assessment was conducted on the three types of ecosystem services: water supply,soil retention,and water purification in the study area.Based on this,the spatial pattern of three types of ecosystem services such as water supply,soil retention,and water purification were analyzed from the perspective of regional scale,county scale,and different types of land use.The spatial pattern of system services were analyzed,and then the trade-offs of three types of ecosystem services based on different scales were discussed.At the same time,the multiple ecosystem service hotspots in Hehuang area were identified and multiple ecosystem services were classified.The main conclusions were as follows:(1)As a whole,the spatial pattern of water supply services and soil retention services in the Hehuang area was basically the same,showing a decreasing trend from west to east.The counties with the strongest water supply service capacity was Gannan which is the part of the Gansu Province in the study area,and the water supply capacity in some areas of Qinghai Province was relatively better.For water purification services,the distribution of nitrogen and phosphorus in the space is basically the same,and the best water purification services were in the south and southeast of the study area.(2)The water supply capacity of forestland and grassland in the study area were strong,and the contribution rate to the total water supply was also the largest;The forestland with the strongest soil retention capacity,followed by the unused land,The largest contribution to total soil retention was grassland,followed by forestland;The strongest water purification capacity was farmland,followed by grassland,The largest contribution to the total water purification was grassland,followed by farmland.(3)There were both trade-offs and synergy between the three types of ecosystem services in Hehuang area.On the county scale,the dominant relationship were that water supply and water purification services was positive correlation,water purification and soil retention was negative correlation.At the regional scale,there were synergetic relationship between water supply services and water purification services,water supply services and soil retention services,and there was a trade-off between water purification and soil retention services.Water supply and water purification have the strongest synergies.From the perspective on the ecosystem service type,the cooperation between supply services represented by water supply in the Hehuang area and regulated services represented by water purification was synergistic.The same was true of supply services represented by water supply,and support services represented by soil conservation.But,the balance between regulating services represented by water purification and support services represented by soil conservation was a trade-off relationship.(4)The multiple ecosystem services in Hehuang area were mainly type 2 and type 1 services,followed by type 0.The type 3 with the strongest service capacity accounted for the smallest proportion and were mainly distributed in the Qinghai Province of the study area and there was a small amount of distribution in the southern part of Gansu Province in the study area.