Spatiotemporal Changes And Tradeoffs/Synergies Of Ecosystem Services In Longzhong Loessal Hilly Area Under The Perspective Of Social-Ecological System

The social-ecological systems(SES)is the basis for the existence and development of human and society.It is also the hotspot and core issue of current research on sustainability and global change.The social-ecological systems emphasizes the integrity and coordination between human society and the natural environment,it is also an important proxy of the research on regional environmental changes and the relationship between man and nature.Land use is the result of human long-term production and governance activities.Land use is also the result and proxy of the comprehensive social-ecological systems.Social-ecological systems is a new interdisciplinary,comprehensive analysis method and research framework,which will enhance the further understanding of the relationship between man and nature,and the social relationship between man and man.The dynamic changes of human activities and social-ecological systems will inevitably affect and change the types,structures and ecological processes of surface systems,which will in turn result in the changes of ecosystem services.In this paper,Anding District,Dingxi City in Longzhong Loess Hilly Region was selected as a case to show the spatiotemporal changes of social-ecological system and the tradeoffs/synergies of the typical ecosystem services,based on remote sensing images,socio-economics data,related geographic maps,ecological models and geospatial analysis methods.In this paper,firstly,the spatial and temporal changes of social-ecological systems in Anding District was analyzed.Secondly,the spatial and temporal patterns and changes of typical ecosystem services such as regional soil conservation,habitat quality,and grain provision was mapped and compared.Then the benefits of ecosystem services under different development scenarios and their tradeoffs and synergies were studied.Preliminary conclusions were listed as below:(1)From 1995 to 2015,the area of different social-ecological systems types in Anding District changed significantly,with a comprehensive dynamic of 0.93%from1995 to 2005 and 1.11%from 2005 to 2015.The farmland ecosystem was increasing,but the increase rate was decreased gradually.The area of the forest ecosystem growed steadily.The area of the grassland ecosystem was decreasing gradually.The area of water increased too.The area of the habitat social-ecological systems increased greatly.The transformation of the social-ecological systems mainly happened among the farmland ecosystem,grassland ecosystem and forest ecosystem.(2)From 1995 to 2015,the amount of soil conservation in Anding District showed a trend of decreasing first and then increasing.As to the soil conservation change at the township scale,in 1995,2005 and 2015,the townships with the highest soil retention were Gaofeng Township,Gaofeng Township and Xinji Township,respectively,and the townships with the lowest soil retention were Xigongyi Township,Fujiachuan.From 1995 to 2015,the soil retention of the farmland ecosystems was generally belong to a moderate level;the soil retention of the forest ecosystems were mainly belong to a lower level;the change of the soil retention of grassland ecosystems were not obvious;the soil retention of the water ecosystems were mainly belong to a low level.The other social-ecological systems mainly belong to the lower levels.The habitat social-ecological systems were mainly distributed in all the soil retention level.(3)From 1995 to 2015,the habitat quality in Anding District gradually improved,but the overall habitat quality belongs to the middle and low levels.The area with higher habitat quality has increased significantly(from 334.22 km~2 to 764.01 km~2),and mainly distributed in the southwestern and northern,central parts of Anding District.The area with low habitat quality has increased from 78.96 km~2 to 160.34km~2 from 1995 to 2015,and mainly distributed in the urban area where the municipal government is located and the surrounding river valleys.As to the change of habitat quality at the township scale,the areas with the highest habitat quality in 1995,2005and 2015 were Gaofeng township;and the areas with the worst habitat quality were Gejiacha township,Qinglanshan township and Ningyuan Township township.Under the perspective of the different social ecological systems,the habitat quality from1995 to 2015 can be ranged as forest ecosystems>water ecosystems>grassland ecosystems>farmland ecosystem>habitat social-ecological systems>other social-ecological systems.(4)The grain provision services increased significantly,with the average values of 11.36×10~6 yuan,33.66×10~6 yuan,and 62.02×10~6 yuan in 1995,2005,and 2015,respectively.Spatially,the grain provision capacity in the eastern parts of Anding District is higher than that in the western.As to the change of grain provision at the township scale,the highest areas of grain provision in 1995,2005,and 2015 were Gejiacha township,Qinglanshan township,and Ningyuan township,respectively.The lowest areas were Gaofeng township.Under the perspective of the different social ecological systems,the grain provision in 1995-2015 is represented as farmland ecosystem>grassland ecosystem>forest ecosystem.(5)Based on three scenarios of ecological construction,urban-rural expansion,and natural development:In the context of ecological construction,the ecosystem service change index(ESCI)of the soil conservation and habitat quality showed benefits with the loss of the ESCI of grain provision.As to the urban-rural expansion scenario,the ESCI of soil retention showed benefits with the ESCI of habitat quality and grain provision loss.As to the natural development scenarios,the ESCI of the soil conservation,habitat quality,and grain provision are all benefit.(6)In the different scenarios,the correlation between service pairs is quite different.The habitat quality was the dominant service type of the soil conservation-habitat quality pairs(SC-HQ),and the relative benefits were significantly higher than that of soil conservation.The benefit of the grain provision was higher than that of soil conservation service of the soil conservation-food supply pairs(SC-FS).In habitat quality-food supply(HQ-FS),The relative benefit of habitat quality was slightly greater than that of the food supply of the habitat quality-food supply pairs(HQ-FS).The comprehensive benefit value of the three scenarios can be ranged as the natural development scenario>urban and rural expansion scenario>ecological construction scenario.Compared with the other two scenarios,the natural development scenario is more suitable for the coordinated development of ecosystem services in Anding district in the loess hilly areas.