Assessment Of Ecosystem Service Value And Construction Of Ecological Security Pattern In Yellow River Basin

The Yellow River Basin has complex climatic and geological conditions,fragile ecosystems,and a series of ecological and environmental problems caused by accelerated urbanization and economic development;at the same time,the Yellow River Basin is an important national ecological barrier area and a major grain producing area,which is crucial to national ecological security and economic development.In this paper,based on five periods of land use data in the Yellow River Basin from 2000 to 2020,the value of ecosystem services is calculated by correcting the ecosystem service value equivalent per unit area through grain yield,rainfall and socio-economic data,analyzing its spatial and temporal evolution,evaluating the synergy and trade-off relationship of ecosystem services on this basis,and using geographic probes to Explore the influencing factors of ecosystem service value changes;finally,identify ecological corridors,ecological pinch points and ecological barrier points based on circuit theory and ecosystem service value hot and cold zones,construct the ecological security pattern of the Yellow River Basin,and evaluate the ecological security status of the basin.The research results of this paper are as follows:(1)The total ecosystem service value in the Yellow River Basin from 2000 to 2020 showed a continuous negative growth trend,decreasing by 19.297 billion yuan during 20a.The structure of ecosystem services in the Yellow River Basin is relatively stable;grassland has the highest contribution to the value of ecosystem services,and the negative effect of construction land on ecosystem continues to increase;from the perspective of land use transfer,bare land and shrubland transfer value is positive flow,construction land and glacial snow do not flow to other land use types,and the rest of land use are negative flow,bare land to grassland transfer makes the value of ecosystem services in the basin increase the most,and the transfer of arable land to construction land decreases the most.The spatial distribution of ecosystem service values in the Yellow River Basin is relatively stable over the 20a period,and the value is high in the south and low in the north;from the spatial distribution of ecosystem service value changes,67.43%of the total value of the basin grids are basically unchanged,and the grids with significant and slight increases account for 11.91%of the total.From the spatial distribution of cold spots and hot spots,the distribution of cold spots and hot spots of total service value,regulating service value,supporting service value and cultural service value is basically the same and does not change between 20a.The spatial distribution of cold and hot spots of total service value,regulating service value,supporting service value and cultural service value is basically the same and does not change significantly between 20a.(2)From the perspective of ecosystem service synergy and trade-offs,among 55 groups of ecosystem service relationships in the Yellow River Basin,only 6 groups of negative correlations exist,and the whole basin is dominated by synergistic relationships.The results of spatial expression of synergistic trade-off relationships of ecosystem services in the basin according to the bivariate local Moran index show that 28.18%of the total number of synergistic grids in the basin and 8.34%of the grid of trade-off relationships.The results of geographic probe to explore the influencing factors showed that vegetation cover>net primary productivity of vegetation>population density>temperature>rainfall>slope>intensity of land development>economic density>distance from roads>urbanization rate>distance from government sites>distance from rivers.The interaction detection results showed that the interaction effect of any two influencing factors showed an enhanced relationship;meanwhile,the average degree of influence of the interaction between natural factors in the watershed was greater than that within the socio-economic factors and the nature-socio-economic interaction.(3)The ecological source sites were identified from the perspective of ecosystem service value and patch connectivity.134 ecological source sites were obtained,with an area of103,369.4 km~2,and the largest patch area of 21,726.10 km~2.17 primary ecological source sites,mostly clustered and contiguous,were located in the upper reaches,mainly in Zaling Lake,Eling Lake and wetlands in the source area of the Yellow River;the middle reaches were concentrated in the western side of Taihang Mountains,the northern side of Qinling Mountains.The middle reaches are concentrated in the western side of Taihang Mountains,the northern side of Qinling Mountains and Luliang Mountains,accounting for more than 80%of the ecological source areas;the lower reaches are dominated by Dongping Lake and Luzhong Mountains.There are 117secondary ecological source sites,accounting for 6.41%of the total area,mostly scattered in the upper,middle and lower reaches.On the whole,the ecological source areas show the distribution pattern of"more in the north and less in the middle,more in the east and less in the west";the low resistance area and lower resistance area in the Yellow River Basin account for 19.32%and23.38%of the total area respectively,mainly in the downstream North China Plain,the middle resistance area is concentrated in the Loess Plateau,and the higher resistance area is mainly in the western part of the basin,accounting for 13.78%.(4)288 ecological corridors in the Yellow River Basin were identified by Linkage Mapper tool,the upstream and downstream corridors are dense and short,and the midstream corridors are sparse and long;49 ecological obstacle points with no improvement score and 66 obstacle points with improvement score were identified,and three levels of obstacle areas were divided,the low level obstacle areas accounted for 88.76%of the total area of obstacle areas,the medium and high level areas were 15172.42km~2,16082.02km~2,grassland and woodland accounted for a larger proportion of the total area,reaching 54.90%and 33.74%respectively;38 ecological pinch points were identified;according to the"Yellow River Basin Ecological Protection and High Quality Development Plan"superimposed on the relevant elements obtained,forming a"one belt,five zones,multiple corridors and multiple points.The ecological security pattern of"one belt,five zones,multiple corridors and multiple points"is formed,and protection strategies are proposed to guarantee the ecological security of the Yellow River Basin from the perspective of ecological zones,ecological sources and ecological corridors.