| As one of the major sediment sources of the Yellow River,the ecological and environmental problems in the ten tributaries area are more serious.On the one hand,urbanization and agricultural expansion have increased the supply pressure of the ecosystem;on the other hand,the implementation of policies such as afforestation and reforestation has enhanced the regulating capacity of the ecosystem.Therefore,it is of great theoretical and practical significance to study the spatial and temporal variation of ecosystem services in the ten tributaries area,to clarify the impact of land use changes on ecosystem service functions,and to reveal the trade-off and synergistic relationship of different services for scientific and rational watershed ecological management and restoration.Based on the land use/cover changes in the last 30 years in the ten tributaries area,this thesis uses the In VEST model to quantitatively assess soil conservation,habitat quality,water production and carbon storage,and on this basis,we explore the spatial and temporal variation of ecosystem services and their spatial and temporal divergence patterns,and analyze the spatial and temporal variation of each ecosystem service in different land use types.The results of the study can provide a reference for sustainable land use management and ecological management in the region.The main findings are as follows:(1)During 1990-2020,grassland and forest land were most widely distributed and occupied a large proportion of the total area,accounting for more than 60%of the study area.Due to the rapid development of urbanization and the implementation of ecological projects such as the return of cultivated land to forest and grass and the Three Northern Protected Forests,the conversion of various land use types in the period 1990-2020 was frequent,especially the conversion of cultivated land,forest land,grassland and unused land was the most significant,with 2570.32 km~2 of grassland converted to forest land,901.43 km~2 converted to cultivated land,564.73 km~2 converted to grassland and 514.73km~2 converted to forest land.The conversion of grassland to forest land was 2570.32 km~2,to cropland was 901.43 km~2,to grassland was 564.73 km~2,and to forest land was 514.05km~2.(2)Soil conservation,habitat quality,water production and carbon storage in the ten tributaries area showed an increasing trend during the four study periods from 1990 to2020.During the study period,the high value of soil conservation service is mainly distributed in the hilly and ravine areas in the upper part of the ten tributaries area,and the land use types are mainly woodland and grassland,while the low value is mainly distributed in the alluvial plain areas in the lower part,and the main land use types are arable land and construction land.The high value areas of habitat quality and carbon stock are mainly located in the southeast area of the ten tributaries area,where the forest and grassland cover a larger area and the ecological environment quality and rainfall conditions are better.Different land use/cover types have the capacity of different types of ecosystem service functions;forest land has the highest soil conservation,habitat quality and carbon storage service functions,and the highest water production service function is for construction land,and the four ecosystem service functions have high spatial correlation in spatial distribution and obvious spatial clustering characteristics.(3)The interrelationships among the four ecosystem services in the ten tributaries area were basically stable during the study period,with synergistic relationships between soil conservation and habitat quality,water production,and carbon storage,but the degree of synergy varied,with habitat quality showing synergistic relationships with carbon storage,shifting from synergistic to trade-off relationships with water production,and shifting from synergistic to trade-off relationships with carbon storage.(4)Based on geographic probes to detect the drivers of each ecosystem service function,the main drivers of soil conservation are slope,rainfall,land use and vegetation cover;the main drivers of habitat quality are land use type,followed by rainfall,GDP and elevation;the main drivers of water production are rainfall,elevation and land use type;the main drivers of carbon storage include land use,NDVI,elevation,temperature,etc.(5)The self-organization mapping method is used to divide the four ecosystem service functions in the ten tributaries area into four ecosystem service clusters,i.e.,the dominant ecosystem service functional areas,I for habitat quality and carbon storage services,II for water production services,III for soil conservation,habitat quality and carbon storage services,and IV for lower ecosystem services.Combining the spatial autocorrelation distribution characteristics of each ecosystem service,the ten tributaries area that need ecological function maintenance or restoration are identified as soil conservation and soil erosion comprehensive control area,Kubuqi wind and sand area comprehensive management area,farmland ecological improvement area and construction land ecological protection coordination area. |
