Study On Supply And Demand Of Ecosystem Services In Fenhe River Basin Based On InVEST Model

Ecosystems provide human beings with raw materials and necessary living conditions for production and life,and human beings have needs for ecosystem products and services.With the continuous progress of social economy,human beings are exerting more and more influences on the ecosystem based on their own needs.The contradiction and conflict between supply and demand of ecosystem services have intensified,even affecting the well-being and sustainable development in the region.At present,the quantitative research of ecosystem service supply and demand is becoming mature,and the impact of topographic factors on the heterogeneity of ecosystem services needs to be further explored.The spatial matching relationship of ecosystem service supply and demand in watershed has become a hot topic in coordinating regional ecological protection and economic development.Fen River is the second largest tributary of the Yellow River.Fen River basin is also a typical ecological fragile area.As human-influenced activities intensify,it is urgent to identify the supply and demand of ecosystem services in the basin to obtain sound advice.In this study,the Fenhe River Basin was selected as the research area,using remote sensing,InVEST model,Gl S,Geo Da,and mathematical methods.Firstly,the supply,demand and matching degree of four ecosystem services,namely water production,grain production,soil conservation and carbon sequestration,were calculated in the Fenhe River Basin in 2000,2010 and2020.Secondly,based on the above analysis,the change rules and spatial matching characteristics of the four kinds of ecosystem service supply and demand matching degree under different topographic gradients in 2020 were analyzed.The results of this study can provide a theoretical basis for policy makers to make policies in the appropriate spatio-temporal range,so as to promote the sustainable and healthy development of the Fen River Basin ecosystem.The main conclusions are as follows:(1)The annual water service supply of Fenhe River Basin in 2000,2010 and 2020 was1.05×10~6t,1.22×10~6t and 3.13×10~6t,respectively;Water production service demands were2.15×10~7t,2.40×10~7t and 3.23×10~7t,respectively.Supply and demand indexes were-0.074,-0.109 and-0.018,respectively.In terms of total volume,the supply of water production service is less than the demand,but the development is good.The supply and demand level of water production service is the worst in elevationⅡ,the second worst in elevationⅠ,and the supply and demand level of water production service is getting better in the area above 987 m.Low supply-high demand type and high supply-high demand type are adjacent in space.(2)The annual supply of grain production services of Fenhe River Basin in 2000,2010and 2020 was 1.28×10~6t、2.64×10~6t and 3.61×10~6t,respectively;The service demands for grain production were 2.81×10~4t、2.64×10~4t and 4.28×10~4t,respectively.The supply and demand indexes were 0.066,0.150 and 0.092,respectively.In total,the supply of grain production services in the basin exceeds the demand.The supply and demand level of grain production service is the best in class I of all topographic factors,and it decreases obviously in classⅡ,and fluctuates slightly with the increase of elevation.As the altitude increases,the slope becomes steeper and the vegetation cover decreases,so the grain production level declines slightly.Most of these areas are low-supply-low demand spatial matching.(3)The annual carbon sequestration service supply of Fenhe River Basin in 2000,2010and 2020 was 2.79×10~8t、2.79×10~8t and 2.72×10~8t,respectively;The carbon sequestration service demands were 2.03×10~6t、2.31×10~6t and 2.46×10~6t,respectively.Supply and demand indexes were 0.688,0.625 and 0.497,respectively.In terms of total volume,the supply of carbon sequestration services exceeded the demand,but the balance index of supply and demand decreased continuously in the past 20 years.The supply and demand level of carbon sequestration service increases with the elevation,and these areas are mainly characterized by high supply-high demand type or high supply-low demand type.(4)The annual soil conservation service supply of Fenhe River Basin in 2000,2010 and2020 was 2.55×10~8t、2.61×10~8t and 3.85×10~8t,respectively.Soil conservation service requirements were 1.34×10~6t、1.35×10~6t and 1.90×10~6t,respectively.The supply and demand indexes were 0.065,0.063 and 0.072,respectively.In total,the demand of soil conservation service is less than the supply.The ratio of supply and demand of soil conservation services increased with the increase of elevation,slope,topographic relief and topographic potential index,but the increase of soil conservation service supply and demand level at elevationⅢandⅣwas the least.The basin is mainly low supply and low demand type,and distributed in the middle of the basin with the elevation of classⅠand ClassⅡ.The high-supply and high-demand type is mainly located in the area with gradeⅤslope on both sides and woodland vegetation cover type.