| The Loess Plateau is a typical fragile habitat in China,and is also a hotspot for the implementation of the " Grain for Green " project.To clarify the spatial and temporal evolution of land use and ecosystem services in the Loess Plateau and their interrelationship is essential for the sustainable management of the ecosystem.Based on this,this study takes the Loess Plateau as the study area.Firstly,we use GIS spatial analysis technology to elucidate the spatial and temporal patterns of land use changes on the Loess Plateau from2000 to 2020,using a five-year study period;secondly,by interpreting MODIS satellite data and combining with the In VEST model,we investigate the spatial and temporal patterns of vegetation net primary productivity(NPP),water resources and ecosystem services on the Loess Plateau at different scales(time,climate zone and land use type).Finally,based on MATLAB meta-statistical mapping,geographically weighted regression(GWR),hotspot analysis and geographic probes,the functional trade-offs and synergies of ecosystem services on the Loess Plateau over long time series and the spatial heterogeneity of the impacts of different land use practices were clarified,and the hotspot areas for ecosystem services were identified.The study identifies hotspot areas for ecosystem services and screens the dominant factors influencing ecosystem service functions,providing scientific support for ecosystem management on the Loess Plateau.(1)In the 20 years since the return of farmland to forest project,the Loess Plateau has undergone a shift from arable land to grassland,forest land and construction land,and from grassland to forest land and from unused to grassland,with the most dramatic change in land use in the semi-arid climate zone.The main land uses in the Loess Plateau are grassland,arable land and forest land,which account for about 93% of the total area of the Loess Plateau;arable land is mainly concentrated in the Loop Plain,the southern part of the Loess Plateau Gully and the southeastern part of the Loess Plateau,forest land is mainly distributed in the eastern and southern parts of the Loess Plateau,and grassland is distributed in all climatic zones.over the 20-year period,the area of forest land has increased the most,while the area of arable land has decreased the most;at the same time,shrubs showed the greatest decline and building land the greatest increase,the results underlining the significant effect of the reforestation project.In terms of the different climatic zones,arable land decreased significantly in the plateau,semi-arid and semi-humid zones;forest land increased significantly in the plateau,arid and semi-arid climatic zones;grassland increased significantly in the semi-arid and semi-humid zones;shrubs decreased to some extent in all climatic zones except for the arid zones;water area increased in all four climatic zones;it is worth noting that the increase in construction land was greater in all four climatic zones.In addition,the dynamic attitude of each land use in the Loess Plateau is higher from 2000 to2010 than from 2010 to 2020,with the exception of forest land.(2)In the context of land use change,NPP,water connotation and soil conservation services in the Loess Plateau region increased over a 20-year period.From a temporal perspective,the average increases in NPP,water connotation and soil conservation services per unit area on the Loess Plateau from 2000 to 2020 were 65.84%,78.27% and 82.82%respectively;from a spatial perspective,the vegetation NPP on the Loess Plateau showed an increasing trend from northwest to southeast,and the areas with higher value-added were mainly located at the junction of semi-arid and semi-humid zones;water connotation services showed The distribution characteristics of low in the northwestern region and high in the southwestern and southeastern regions,with the area occupied by high value areas of water connotation services in the southern part of the plateau area,the semi-humid zone and the semi-arid zone increasing year by year;soil conservation services show a spatial distribution pattern of high in the middle and low in the periphery,especially in the eastern part of the semi-arid and semi-humid zone,the junction and the plateau area providing higher services,while in the junction of the semi-arid and semi-humid zone and the southeastern part of the semi-humid zone There is a significant increase in(3)There are strong spatial differences in the effects of different land uses on the synergistic relationship between NPP,water connotation and soil conservation services on the Loess Plateau,and rainfall and land use are key drivers of ecosystem service functions and hotspot areas.20 years ago,the synergistic relationship between NPP,water connotation services and soil conservation services on the Loess Plateau was dominant,and the trade-offs were generally distributed in peripheral areas;different There is spatial heterogeneity in the relationship between different land use changes and the trade-off/synergistic relationship between ecosystem services,with grassland area change having the greatest positive influence on the trade-off/synergistic relationship between NPP and water-harvesting services,water area change having the greatest negative driving effect on NPP and soil conservation services,and woodland change having the greatest positive driving effect on water-harvesting and soil conservation services.In addition,the identification of ecosystem service hotspots revealed that the number of hotspots on the Loess Plateau gradually increased from northwest to southeast,with the area of non-and primary hotspots decreasing over 20 years and the area of secondary and tertiary hotspots gradually increasing.The interactions between the drivers are greater than those between individual factors. |
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